That is not to say these additional features take precedence over air cleaning — quite the opposite. The SwitchBot Air Purifier Table features not one but three air filters: a HEPA filter that eliminates 99.97% of airborne pollutants as small as 0.3 microns (such as pollen, dust mite allergens and mold spores, for example), an activated carbon filter that helps reduce pesky odors and common household pollutants like volatile organic compounds (VOCs), and, lastly, a washable pre-filter that catches dust, pet hair and other large particles.

Unlike most appliances on the market, it also offers 360-degree purification, meaning its air inlets are located all around the unit rather than on one side only. Finally, the SwitchBot Air Purifier Table promises whisper-quiet fans and a designated Pet mode. It costs $269.99, so it is not particularly budget-friendly, but price aside, it could be one of the best air purifiers for animal lovers and people with airborne allergies.

SwitchBot Air Purifier Table review

SwitchBot Air Purifier Table: Design

• Light, portable and stylish
• Adjustable ambient lighting in 10 colors
• Pet-friendly design

The SwitchBot Air Purifier Table comes in two parts: the main body and a detachable tabletop. The assembly is not too difficult, but it does require sharp eyesight and a good level of manual dexterity.

The cable connector that links these two pieces is quite fragile, so we had to be careful not to squash it during installation. Also, the screws that secure the tabletop in place are horrendously tiny, and the two holes that they are supposed to go in are located in a narrow, hard-to-reach space underneath the lamp. We managed to put this air purifier together without injuring ourselves or damaging the unit, but it was one of the trickiest assemblies we have ever had to undertake. If your hands are not as steady as they used to be, you may want to ask someone else to help you.

Once the unit is fully assembled, set-up is a breeze. All you need to do is unwrap the filters, pop them back in and connect your air purifier to the SwitchBot app. The process is swift and takes less than a couple of minutes, and we did not experience any issues with connectivity.

Moving the unit around was easy, too. The SwitchBot Air Purifier Table weighs just 10.68 lbs (4.85 kg) and measures less than 20 inches (50 cm) in height. It does not take up much floor space either, making it a good option for small rooms.

Its aesthetics also scored highly in our books. While it is not unusual to see a table air purifier, it is rare to see a model this stylish. The tabletop has a lovely "wooden" color and pattern, while the control panel is discreetly hidden from view underneath it. The SwitchBot Air Purifier Table looks more like a piece of furniture than a household appliance, and won’t stand out like a sore thumb.

We particularly liked its adjustable ambient lighting. This comes in 10 colors, from white to bright blue and deep purple, and you can decide how bright you want it (Bright, Moderate or Soft) and whether you need it on, off, or on auto mode (it will automatically turn off in low ambient light). This way, the SwitchBot Air Purifier Table can serve as a nightlight or a mood lamp to create a cozy atmosphere in the evening.

The animal-friendly design was another big plus point for us. The SwitchBot Air Purifier Table features a waterproof tabletop, so you can let your pets sit or rest on it without worrying about damaging the unit or putting their safety at risk. This air purifier also features a wide, soft-edged grille that will not trap curious paws and a low-voltage, bite-resistant cord. Plus, the washable pre-filter allows you to get rid of pet hair without having to buy a brand new replacement.

Speaking of replacement filters, they cost $44.99 per pack and are available on the official SwitchBot website. While they are not particularly cheap, they are priced similarly to competitors' products.

SwitchBot Air Purifier Table: Features

• Auto, Pet and Sleep modes
• Built-in wireless phone charger and fragrance dispenser
• Wide compatibility with smart home apps

The SwitchBot Air Purifier Table features three manually adjusted fan speeds and three modes. In Auto mode, it automatically changes the fan speed based on readings from built-in air quality sensors, all while maintaining relatively low noise levels. In Pet mode, the fans work at a higher speed than Auto mode to better clear unpleasant smells and pet hair. Sleep mode, on the other hand, is designed to make as little noise as possible while still purifying the air in line with the changing pollution levels.

The SwitchBot Air Purifier Table is compatible with the SwitchBot app and a wide range of smart home apps, including Apple's Siri, Google Home, Amazon's Alexa, SmartThings, and Home Assistant. This means it can be easily controlled via your phone or by using voice commands. These smart features also allow you to track changes in air quality (down to the last 30 days), set timers and keep an eye on the filter's lifespan.

And, as we mentioned before, the SwitchBot Air Purifier Table features a fragrance dispenser (scented oils have to be purchased separately) and a wireless phone charger that supports 15W charging for Android and 7.5W charging for iPhone. All in all, features are where this appliance shines the brightest.

SwitchBot Air Purifier Table: Performance

• Whisper-quiet at low fan speeds
• Good air-cleaning performance in small to medium spaces
• Auto mode can be somewhat sluggish

According to the manufacturer, the SwitchBot Air Purifier Table is best suited for rooms measuring up to 360 square feet (33.45 square meters). While this appliance is often advertised as a great option for larger spaces — it promises to "purify a house of up to 3,620 square feet in just one hour," for example — it will take much longer to purify the air in these circumstances and as such, its overall effectiveness may be significantly diminished. That is because its Clean Air Delivery Rate (CADR) rating is 236 CFM, meaning it does not clean more than 236 cubic feet of air per minute (you can read more about CADR ratings in our guide on how to choose an air purifier.) For best results, we would recommend placing the SwitchBot Air Purifier Table in small- to medium-sized rooms.

No matter where you place this air purifier, though, it is unlikely to cause you any nuisance, because it is whisper-quiet. We can back the manufacturer's claims here — when we used the Sound Meter decibel-counting app to measure its noise levels at the lowest fan speed, we recorded a mere 21 dB. To put that into perspective, 21 dB is equivalent to leaves rustling in the wind or a buzzing mosquito. When we switched to the highest fan speed, we noted just 57 dB, comparable to a quiet refrigerator or office sounds. As it stands, the SwitchBot Air Purifier Table is one of the quietest household appliances we have tested.

The SwitchBot Air Purifier Table seemed to do a good job of keeping airborne pollutants at bay, kicking into high fan speeds whenever we sprayed cosmetics, used cleaning chemicals or cooked a meal. The air felt considerably fresher, too, though some of the more premium air purifiers we tested were more effective at reducing unpleasant smells than our SwitchBot.

We can't vouch for its overall effectiveness for animal lovers — we do not have any pets and no animals took part in our testing process — but we reckon this air purifier has what it takes to make a tangible difference to households with furry inhabitants.

That said, the performance of the SwitchBot Air Purifier Table may depend on the mode it is used in. When we conducted a series of performance tests using a Perfect Prime air particle monitor, a professional-grade device capable of detecting airborne particles as small as 0.3 microns, we noted considerable differences between the auto and pet modes. This was particularly pronounced during our ambient air tests.

We placed our SwitchBot in a medium-sized room and ran it for 30 minutes in auto mode. During the first 15 minutes, this air purifier removed only 30% of particles measuring 0.3 microns and 25% of particles measuring 2.5 microns, which after 30 minutes rose to just 57% and 50%, respectively.

When we repeated this test in pet mode, however, the results were much better. During the first 15 minutes, our SwitchBot removed 58% of 0.3-micron particles and 72% of 2.5-micron particles. After 30 minutes, these values increased to 79% and 85%, respectively. No particles larger than 10 microns were detected during these tests. While these numbers may not be impressive (many air purifiers produced better results in our ambient tests), we still consider them very good for an appliance this small and quiet.

The SwitchBot Air Purifier Table did perform more consistently during our smoke tests. During these tests, we challenged it to different types of heavy air pollution, first by burning 10 incense sticks, then by lighting up 10 matches. We placed our SwitchBot in an enclosed, medium-sized room, then measured the air quality before and after running it for 30 minutes. In auto mode, the air purifier removed on average 88% of particles measuring 0.3 microns, 92% of 2.5-micron particles and 99% of particles larger than 10 microns. In pet mode, these values were only higher by around two to five percentage points.

SwitchBot Air Purifier Table: User reviews

The SwitchBot Air Purifier Table was rated an impressive 4.5 out of 5 stars at Amazon. Positive reviews tended to praise this multi-purpose appliance for its robust air quality monitoring, small footprint, whisper-quiet fans and multiple smart features, with many users appreciating its pet-friendly design and adjustable ambient lighting.

One user commented, "This is a fantastic air purifier! [...] With the bad air quality from the recent Los Angeles fires, my bedroom (12 x 14 room) started out with 'moderate' air quality, but after running the filter for about 45 minutes, it moved to good and then very good eventually. I can also schedule when I want it on and off and the best thing is that it tells how many filter hours I have remaining."

Negative reviews, though few and far between, often revolved around the relatively high price, low purification power and limited availability of replacement filters.

Should you buy the SwitchBot Air Purifier Table?

✅ Buy it if: You are a pet owner looking for a smart air purifier, or just love a multi-purpose gadget. The SwitchBot combines good looks, extensive functionality and pet-friendly design, and does a great job of ridding rooms of bad smells and airborne pollutants.

❌ Do not buy it if: You are looking for an air purifier that can cover larger spaces or want something more budget-friendly.

If the SwitchBot Air Purifier Table is not for you

Levoit Vital 200S is a great alternative to the SwitchBot Air Purifier Table. While it will not store your books or serve as a napping station for your cat, this powerful air purifier features plenty of pet-friendly features and connects to several smart home apps, including VeSync, Amazon Alexa and Google Assistant. Plus, it is cheaper by about $80.

Looking for something even more budget-friendly? The GermGuardian AC4825E is a great option here. It is only 22 inches tall and 10 inches wide, so it will easily slot into a narrow space, and it comes with a HEPA filter, an activated carbon filter, UV-C sanitizer and easy-to-use controls — all for less than $100.

If you love unique design, consider the RabbitAir A3. This air purifier costs a whopping $750 but is well worth the money. Not only does it come in multiple beautiful colorways, it also boasts powerful air-cleaning performance, five different air filters and the coveted Asthma and Allergy Friendly certification.

SwitchBot Air Purifier Table: How we tested

We spent nearly a month testing the SwitchBot Air Purifier Table, thoroughly assessing its design, features, day-to-day performance, ease of assembly and connectivity with third-party devices. We also used a Sound Meter decibel-counting app to measure how loud this air purifier was on different settings.

Then, we performed a series of air quality tests using a Perfect Prime air particle monitor, a professional-grade device capable of detecting airborne particles as small as 0.3 microns. We started with ambient air quality tests: first, we put the SwitchBot Air Purifier Table in an enclosed, medium-sized room and ran it on auto mode for 30 minutes, taking air quality readings every 15 minutes. Then, we repeated the procedure on pet mode.

Next, we conducted several smoke tests. We burned matches and incense sticks to create different types of heavy pollution, then measured the changes in air quality before and after running the SwitchBot Air Purifier Table for 30 minutes. The smoke tests were first conducted on auto mode, then on pet mode.

Researchers have developed a mathematical model to examine how the brain represents both spatial and semantic information. The latter includes knowledge about the meaning and significance of different people, places and things; brain activity related to these concepts crops up when a person sees a person, place or thing in real time and when they recall it in a memory.

The model showed how both spatial and semantic information could be represented in the same regions of the brain — and this suggests that the brain can handle both types of information in similar ways, the scientists reported March 10 in the journal PNAS.

Two parts of the brain that focus on memory and navigation — the hippocampus and the entorhinal cortex — both contain neurons that fire when people move through their physical surroundings. They also contain neurons that fire in response to certain concepts or ideas, known as concept cells. This led researchers to suspect these thought processes might be related.

Related: Sherlock Holmes' famous memory trick really works

"Spatial representations and conceptual representations, and also semantic computing and spatial computing, seem very different," study co-author Tatsuya Haga, a computational neuroscientist at the National Institute of Information and Communications Technology in Japan, told Live Science. Semantic and spatial computing refer to how brains and computers process information in these separate realms.

"However, there's a connection between those two different things," Haga said. "So maybe the brain, especially the hippocampus and entorhinal cortex, is using one principle to compute many things, including language."

Haga and his colleagues developed a mathematical model that mimics certain functions in the hippocampus to show how these ways of thinking are related. The model combines two functions that help control how the processing hub shifts from one place or idea to another: a successor representation, which predicts the probability of moving from one physical space to another, and word embedding, which captures the relationships between words.

The team then asked their model to navigate a simulated physical or conceptual space. The "physical" space was a simulated structure, sometimes with separate rooms, while the conceptual space involved traversing the metaphorical "distance" between related words using analogies.

In response to these tasks, the model produced patterns that resemble the activity of two kinds of neurons in the hippocampus and entorhinal cortex: one involved in spatial awareness and another involved in concept recognition.

Related: Super-detailed map of brain cells that keep us awake could improve our understanding of consciousness

The team showed that the same algorithm that can be used to navigate virtual spaces can also capture relationships between related concepts, such as countries and their capitals. In this example, to navigate from the concept of "France" to that of "Berlin," the model could first activate a concept cell for capital cities, which would lead it from "France" to "Paris," and then activate an additional cell representing "Germany," which would lead it to "Berlin."

"When you're trying to navigate a maze city, you have to have some kind of map with landmarks and directions," Rob Mok, a computational neuroscientist at Royal Holloway, University of London who was not involved in the study, told Live Science. "And the idea is that you can do that when you're thinking as well."

The model can use various analogies to overcome the metaphorical distance between different semantic concepts.

"So if I'm thinking about a dog, how do I get to 'cat'? Or how do I get to 'king'?" Mok said. "These are different directions, and you might need to navigate in different ways to get there."

The new mathematical model shows one possible way the human brain might process both spatial and semantic information. However, no one has shown whether actual brains learn and process information in the exact same way the model does.

Haga told Live Science that he hopes to investigate this biological mechanism in future work using models that are more similar to biological brains.

The experimental mind-reading technology is designed to give a synthetic voice to people with severe paralysis who cannot speak. It works by putting electrodes onto the brain's surface as part of an implant called a neuroprosthesis, which allows scientists to identify and interpret speech signals.

The brain-computer interface (BCI) uses AI to decode neural signals and can stream intended speech from the brain in close to real time, according to a statement released by the University of California (UC), Berkeley. The team previously unveiled an earlier version of the technology in 2023, but the new version is quicker and less robotic.

"Our streaming approach brings the same rapid speech decoding capacity of devices like Alexa and Siri to neuroprostheses," study co-principal investigator Gopala Anumanchipalli, an assistant professor of electrical engineering and computer sciences at UC Berkeley, said in the statement. "Using a similar type of algorithm, we found that we could decode neural data and, for the first time, enable near-synchronous voice streaming."

Anumanchipalli and his colleagues shared their findings in a study published Monday (March 31) in the journal Nature Neuroscience.

Related: AI analysis of 100 hours of real conversations — and the brain activity underpinning them — reveals how humans understand language

The first person to trial this technology, identified as Ann, suffered a stroke in 2005 that left her severely paralyzed and unable to speak. She has since allowed researchers to implant 253 electrodes onto her brain to monitor the part of our brains that controls speech — called the motor cortex — to help develop synthetic speech technologies.

"We are essentially intercepting signals where the thought is translated into articulation and in the middle of that motor control," study co-lead author Cheol Jun Cho, a doctoral student in electrical engineering and computer sciences at UC Berkeley, said in the statement. "So what we’re decoding is after a thought has happened, after we've decided what to say, after we’ve decided what words to use and how to move our vocal-tract muscles."

AI decodes data sampled by the implant to help convert neural activity into synthetic speech. The team trained their AI algorithm by having Ann silently attempt to speak sentences that appeared on a screen before her, and then by matching the neural activity to the words she wanted to say.

The system sampled brain signals every 80 milliseconds (0.08 seconds) and could detect words and convert them into speech with a delay of up to around 3 seconds, according to the study. That's a little slow compared to normal conversation, but faster than the previous version, which had a delay of about 8 seconds and could only process whole sentences.

The new system benefits from converting shorter windows of neural activity than the old one, so it can continuously process individual words rather than waiting for a finished sentence. The researchers say the new study is a step toward achieving more natural-sounding synthetic speech with BCIs.

"This proof-of-concept framework is quite a breakthrough," Cho said. "We are optimistic that we can now make advances at every level. On the engineering side, for example, we will continue to push the algorithm to see how we can generate speech better and faster."

In the short term, measles, caused by a highly contagious virus, usually causes fever, respiratory symptoms like coughing, and a distinctive rash that spreads from the hairline down the body. It appears as if a "bucket of rash" is poured over the head, according to Patsy Stinchfield, an infectious disease nurse practitioner and the most recent past president of the non-profit National Foundation for Infectious Diseases (NFID).

Because the two-shot measles, mumps, and rubella (MMR) vaccine is 97% effective at preventing measles, many U.S.-based medical professionals have never seen the disease that's now causing a major outbreak in Texas and bordering states, experts told Live Science. Cases have been so low in the U.S. that measles was declared eliminated from the country in 2000.

However, Stinchfield responded to a 2017 measles outbreak in Minnesota and saw multiple kids affected.

"The kids that come into the emergency room and get to go home, even those kids look like rag dolls over their parents' shoulders," Stinchfield told Live Science. "They're miserable."

Related: Are you protected against measles? Do you need a booster shot? Everything you need to know about immunity

An estimated 1 out of every 5 kids who catch measles will be hospitalized, and 1 in 20 will get pneumonia, which is what kills most children who die of the disease, according to the Centers for Disease Control and Prevention (CDC). Some of these hospitalized children will need to be put on a ventilator to recover, Stinchfield said.

In about 1 in 1,000 cases, measles causes brain swelling, or encephalitis, which can cause seizures. When it's not fatal, the swelling itself can subside, but it can cause permanent brain damage and other lasting side effects, such as blindness or deafness.

"Immune amnesia"

Even patients with milder cases of measles can suffer long-term knock-on effects.

Measles binds to a receptor that happens to be present on several important immune cells: T lymphocytes, B lymphocytes, and long-lived plasma cells. These are cells that "remember" past infections for decades, thus enabling the immune system to rapidly mount a defense if it encounters a pathogen again.

It does this by making protective proteins called antibodies, along with summoning other immune defenders. But a 2019 study found that, after a measles infection, people lose between 11% and 73% of the antibodies they had to previous infections.

To recover from this so-called immune amnesia, a person would have to catch all those diseases again, said Stephen Elledge, a geneticist at Harvard Medical School and the senior author of that 2019 research. In the meantime, that means they're vulnerable to a whole host of infections after contracting measles.

Furthermore, a 2015 study led by Elledge's collaborator, epidemiologist Dr. Michael Mina, found that kids who got measles had a higher death rate from other infectious diseases in subsequent years.

These infectious diseases, including measles, are the primary reason that nearly 1 in 5 children died before their fifth birthday in the U.S. back in 1900. A 2024 study published in The Lancet estimated that vaccination has saved at least 154 million lives since 1974, alone.

"The vaccine is much more important than we thought it was," Elledge told Live Science. "It doesn't just save from the 0.1% or 0.2% of children that die [of measles]. It may be the 0.5% to 1% of the kids that get measles [and] might succumb to another infection. That starts to get a little bit bigger."

A lingering threat

The measles virus is capable of replicating in the brain, said Ross Kedl, a professor of immunology at the University of Colorado Anschutz Medical Campus. In some cases, the immune system beats the virus back and the person seems to recover, but measles still lurks in their nervous system.

The nightmarish effect of this long-term persistence is a condition called subacute sclerosing panencephalitis (SSPE). This is a progressive neurological disorder that might start with mood changes and muscle tremors; then, as it progresses, the person starts losing speech, vision and hearing. After about two years, the person falls into a coma and dies.

"The person you knew transforms in front of you and wastes away and then they're gone," Kedl told Live Science.

The risk of SSPE is highest in kids who catch measles before the age of 2, at about 1 in 1,000, Kedl said. For older patients, the risk is closer to 1 in 10,000, which is still twenty times higher than the risk of serious side effects from any vaccine on the market, he said. (1 in 10,000 is 20 in a million, whereas serious adverse events from vaccines occur at a rate of roughly 1 to 2 per million, according to the Department of Health and Human Services.)

Because SSPE is most common in kids who catch measles before age 2, and it tends to emerge about seven years after their acute infection, the victims are typically around the age of 9 or 10.

SSPE happens because the measles virus can go dormant within the nervous system, similar to how the chickenpox virus — called varicella — can go dormant and cause shingles decades later. One benefit of the varicella vaccine is helping prevent the chickenpox infections that can lead to shingles down the line; similarly, the MMR vaccine prevents SSPE.

Measles vaccines save lives and prevent disability

The MMR vaccination has effectively cratered the annual number of U.S. measles cases — which totalled 3 million to 4 million before vaccines were introduced, according to the CDC. Because of the vaccine's success, people forget how bad the disease can be, said Dr. Michelle Barron, senior medical director of infection prevention and control at UCHealth, a medical system in Colorado.

With vaccination rates sliding in various jurisdictions, there are now active measles outbreaks in Texas, New Mexico, Kansas and Ohio, with scattered cases in 16 other states, Barron told Live Science. There are also outbreaks in Mexico and Canada. It's important to be vaccinated to protect both yourself and those who can't be vaccinated, including babies under 1 year old, she said.

There are no treatments for measles that can reduce the risk of the disease's knock-on complications, Barron said. The "natural" remedies that have been pushed by Robert F. Kennedy, Jr. and others, such as vitamin A, are not measles treatments. Rather, they are treatments for malnutrition that are often used to help support kids with measles in places with extreme poverty and childhood malnourishment, Barron said.

What does cut the risk of knock-on effects of measles? Not catching the disease in the first place.

"Vaccine is protective against all of these complications," Barron said.

We all have a vague idea of what the ideal air purifier should be like. First and foremost, it should quickly and efficiently get rid of a wide range of airborne pollutants, from large dust particles to minuscule bacteria and viruses. It should be immensely powerful, but also ultra-compact and whisper-quiet. Functional, yet affordable. And, ideally, beautifully designed.

The problem is, the ideal air purifier simply does not exist. As with anything else in this world, something has to give. We know — we have tested plenty of these appliances over the years. Even some of the best air purifiers come with drawbacks, whether that’s a monstrous size, noisy fans or an eye-watering price.

So what should you be looking at when buying an air purifier? There is no single answer to this question. Choosing an air purifier will largely depend on your preferred outcomes, personal preferences and the space you intend to use it in. You may have to reach some sort of a compromise between price, design and functionality, and get to grips with complex-sounding specifications.

Sound scary? Do not worry. We are making use of our years of experience to help you choose the best air purifier for you. Step-by-step, we will arm you with all the necessary knowledge to get the best value for your hard-earned money. While no air purifier is perfect and the results are never guaranteed, we hope that this guide will help you get through this hay fever season relatively sniffle-free.

Price does not equal value

If there is one thing that we have learned from testing air purifiers is that high price does not equal better quality — and our experts wholeheartedly agree.

"While higher-end air purifiers often provide more features and greater efficiency for large spaces, a well-chosen budget-friendly model can still deliver excellent air quality," Dr. John McKeon, CEO of Allergy Standards, an international certification body for domestic appliances, and a principal at the Indoor Air Innovation & Research Institute, told Live Science by email.

What determines the value of an air purifier is the combination of its purification power (how much air it can clean per unit of time), its filtration technology and whether it is certified by reputable third-party organizations. Even some of the most affordable models meet these three conditions, McKeon said. "Indeed, higher-end purifiers often include air quality sensors, auto mode, mobile app connectivity and other frills, but while convenient, these features are not essential for effective air cleaning," he emphasized.

That said, air purifiers that are efficient at filtering the air in challenging environments — in very large or extremely polluted spaces, for example — tend to be more expensive, McKeon said.

Understand the key specs

So, how do you find the purification power of an air purifier? Understanding the basic terminology will give you the upper hand here. Most models make claims of unparalleled performance, but knowing exactly how much air you want to purify will help you see through the marketing gimmicks and pick an appliance that suits your needs the most.

One of the most reliable ways to evaluate an air purifier’s effectiveness is by understanding its Clean Air Delivery Rate (CADR.) "This standardized rating, measured in cubic feet per minute (CFM), tells you how quickly an air purifier can clean the air in a given space," McKeon said. Air purifiers with higher CADR ratings offer faster, more effective air filtration, while appliances with lower CADR ratings have lower purification power.

So what is the best CADR rating for your needs? "As a rule of thumb, the CADR should be at least two-thirds of the room's square footage. For example, a 300-square-foot room requires a CADR of at least 200 CFM," McKeon said.

Choosing an air purifier with the right CADR rating is particularly important for people with asthma and allergies to airborne particulates like pollen and pet dander. "Ensure the device can accommodate the size of the room it is being placed in or else it will not be as effective," Melanie Carver, chief mission officer of the Asthma and Allergy Foundation of America (AAFA), told Live Science by email.

However, a higher CADR rating does not automatically mean better performance. "More expensive purifiers often have higher CADR ratings, making them better suited for large rooms. However, in a smaller space, a well-matched budget model with an appropriate CADR can perform just as well," McKeon explained.

This brings us to another important specification — the coverage. This refers to the maximum square footage an air purifier is intended for, making it easy for the user to determine if an appliance can be used in their home. However, you should take this metric with a pinch of salt. Most brands will try to inflate the perceived performance of their products by stating the coverage that applies to just one Air Change per Hour (ACH), whereas "to effectively remove airborne triggers, you need at least 4 air changes per hour," McKeon said.

You can calculate how many cubic feet of air an air purifier can clean per hour by taking into account the room's volume (square footage x ceiling height) and the air purifier's CADR rating, McKeon said. Multiply the CFM value by 60, then divide it by the room volume in cubic feet. If you want to see how many cubic feet of air it can purify within the recommended 15 minutes, multiply the CFM value by 15.

If maths is not your forte, find one of the online ACH calculators that can do these equations for you!

Pick the right air filters

Choosing the right filtration technology is another vital aspect when buying an air purifier. That is because it will largely determine the type and amount of pollutants that can be removed from the air.

Almost all of the best air purifiers for allergies work by trapping particles in air filters made of a porous, solid material like plastic or fiberglass. Other appliances work by passing air through an ionizer or electrostatic filter, which gives particles an electrostatic charge that causes them either to stick to metal plates or clump together and fall to the ground, Carver said. Certain air purifiers even combine several different filtration technologies. So which one should you choose?

Our experts agree that a True HEPA (High-Efficiency Particulate Air) filter is one of the most effective. "This filter can capture over 99.9% of airborne particles as small as 0.3 microns, including common allergens like pollen, mold spores, dust mites, and pet dander, making it a crucial feature for those with asthma and allergies," McKeon said. "While premium models may offer additional filtration stages (an activated carbon filter for reducing odors, for example), a budget-friendly unit with a certified True HEPA filter can still be highly effective for smaller spaces," he explained.

However, it is important to note that HEPA filters alone do not guarantee effectiveness. "For example, if there is a HEPA filter in an air cleaner but the seal around it is not tight enough, the air might be able to bypass the filter," Carver said. This is why certifications from reputable organizations are so essential here — they do not just look at the filter used but how the whole appliance functions, she said. More on that later.

HEPA filters are a must, but what about other types of air filters? Whether you need them or not will largely depend on your needs and preferences. For example, many air purifiers are equipped with pre-filters designed to catch larger particles, such as dust or hair strands. In our experience, pre-filters can be very useful if you have pets, fluffy carpets or heavily soiled areas. However, we would not consider them essential.

Some appliances also include activated carbon filters. These thin layers of charcoal are designed to absorb odors and volatile organic compounds (VOCs), which are common household pollutants often characterized by strong, chemical smells. "Activated carbon filters may have benefits for people with asthma that is triggered by these irritants. However, these filters do not effectively trap allergens such as pollen or pet dander, which is why they are often combined with a HEPA filter," Carver said.

Mind you, activated carbon filters are not a magic solution and they will never be a substitute for proper ventilation. Plus, they can differ in effectiveness between brands, if our experiences are anything to go by. Still, activated carbon filters can make a tangible difference to the air quality in your home, especially if you have pets, cook often or use a lot of cleaning solutions or paints in your home.

Finally, a handful of air purifiers are also equipped with ionizers. This feature may not be suitable for everyone, Carver told Live Science.

"While ion generators may remove small particles (e.g, those in tobacco smoke) from the indoor air, they do not remove gases or odors and may be relatively ineffective in removing large particles such as pollen and house dust allergens," she said. "Another thing to note is that certain ionizers may produce ozone as a by-product, and this air pollutant can be harmful to people with asthma. Always look for trusted certifications, such as the Asthma and Allergy Friendly Certification Mark, to ensure there are no ozone emissions," Carver said.

Look for independent certifications

Third-party certifications validate claims made by an appliance's manufacturer and ensure it meets rigorous safety standards. They can help consumers make a more informed and science-backed decision when selecting an air purifier, our experts said. We thoroughly agree. With so many different models available on the market, it is difficult to know if something is truly worth the investment — having that endorsement can help you make the best choice possible.

"Look for certifications like the Asthma & Allergy Friendly Certification Mark, which verifies a high level of allergen removal efficiency and safety against harmful emissions like ozone. This certification ensures that the air purifier has been independently tested and proven to remove over 90% of allergens from the air, not just redistribute them. These products are also assessed for safety, including ozone emissions," McKeon said.

Carved agreed and added: "The Asthma and Allergy Foundation of America (AAFA) joined with Allergy Standards Limited to develop strict standards for product certification. The Asthma & Allergy Friendly Certification mark on an air purifier ensures it meets AAFA’s high standards," Carver said.

Other independent certifications to look for include Energy Star (this means that an air purifier meets strict EPA energy efficiency guidelines), UL 2998 (this ensures that an air purifier does not emit ozone) and CARB (this means that an air purifier has been approved by the state of California’s regulatory air quality agency, which is one of the strictest in the U.S.)

Pick the right design

We have talked a lot about the purifier's performance, and rightfully so, but we can't dismiss the importance of design. Factors such as size, looks, noise levels or controls can make or break your experience with an air purifier, regardless of its ability to filter airborne pollutants. Trust us here — we have downgraded plenty of appliances based on how much of a nuisance they turned out to be in day-to-day life.

When selecting an air purifier, take into account its intended placement to make sure it will not obstruct your living space or create tripping hazards. This is especially important if you have small children or overly curious pets. Also, make sure your air purifier is light enough if you intend to move it around the house a lot. It can be a real hassle, if not downright dangerous, having to lug a big, chunky machine from room to room.

Noise levels are another important factor to consider, particularly if you want to place your air purifier in a study or bedroom. Most appliances make around 40 to 60 dB (depending on the fan speed), which is comparable to a quiet conversation and, for most people, this is not particularly disruptive. However, some air purifiers (especially bigger, more powerful appliances at the cheaper end of the spectrum) can easily make as much as 80 dB when they kick into high fan speeds. That is equivalent to a noise made by blenders or hoovers, and not something that is easy to bear on a regular basis.

Feature-wise, we would recommend investing in an air purifier that has a built-in air quality monitor and an auto mode. Many, if not most, airborne pollutants are invisible to the naked eye, so it is not always obvious if your air quality has worsened. Similarly, it may not always be easy to tell if your indoor air is pristine and you may end up running your device at an unnecessarily high fan speed and wasting electricity for no reason. An air purifier with an air quality monitor and an auto mode can tell you how polluted your air is and adjust the fan speed accordingly. This way, you do not even have to think about it and you can just leave it to do its job. It is an excellent time-saver.

Consider the maintenance costs

The initial investment of buying an air purifier is not the only cost you will incur. First, you will need to account for the price of energy to run the appliance. It is tricky to quantify exactly how much you will pay as it differs from model to model and it will largely depend on your usage. If you are on a tight budget, you may want to consider buying an air purifier that is Energy Star-certified. While it may cost more to start with, it can save you money over time.

Secondly, air filters have a limited lifespan and the replacements can be surprisingly expensive. Most air filters last between six to nine months before they need to be replaced, but this can change depending on your usage and the level of air pollution you want to tackle. If you do now want to be up for a nasty surprise, check the price and expected lifespan of its replacement filters before committing to a specific appliance.

Lastly, check the warranty. In our experience, air purifiers do not break down that often. However, it is good to have peace of mind in case that happens.

This article is for informational purposes only and is not meant to offer medical advice.

Affected populations: Nocardiosis is a rare but potentially deadly infectious disease caused by bacteria in the genus Nocardia. Nocardiosis is an opportunistic infection, meaning it doesn't typically affect healthy people but may seize the chance to infect people with weakened immune systems, such as people with cancer or HIV/AIDS, as well as organ transplant recipients who are taking immunosuppressive drugs.

However, around 20% to 30% of patients with nocardiosis have no known pre-existing conditions, so the infection doesn't exclusively affect people with immune deficits. People over the age of 40, especially men, are also more likely to develop the disease than other demographics.

Between 500 and 1,000 new cases of nocardiosis are reported in the United States every year.

Related: Scientists have found a secret 'switch' that lets bacteria resist antibiotics — and it's been evading lab tests for decades

Causes: Nocardia bacteria are found in soil, standing water and decaying plant material. Around 100 Nocardia species have been identified so far, of which 12 are known to infect humans.

People may become infected with Nocardia bacteria when they inhale dust containing the microbes or they have a cut or scrape that comes in contact with contaminated soil or water.

Nocardiosis is not known to spread from one person to another; people pick it up directly from the environment.

Symptoms: The symptoms of nocardiosis vary depending on which part of the body is infected by Nocardia bacteria.

Most cases of nocardiosis start out as lung infections, in which pus-filled cavities, or abscesses containing the bacteria, form in the lungs. This can cause symptoms such as chest pain, a cough (including coughing up blood), sweats, chills and general weakness.

Nocardia bacteria can then travel in the bloodstream and form abscesses in other regions of the body, including the brain, kidneys and intestines. Infections of the brain can cause headache, weakness, confusion and seizures.

Approximately one-third of all patients infected with nocardiosis develop skin ulcers or sores, instead of an internal infection. These skin lesions typically form across the hands, chest wall or buttocks. They may look like open wounds or bumps under the skin.

Without treatment, nocardiosis can rapidly lead to death, often by causing organ failure or sepsis, a dangerous body-wide immune reaction. Between 16% and 40% of patients with nocardiosis die as a result of their infection. If the disease spreads to the brain, death rates jump to more than 80%.

Treatments: Nocardiosis can be treated with common antibiotics, although these bacteria are normally resistant to penicillin. The antibiotic treatment usually takes between six and 12 months to complete, and some patients may need to take antibiotics for even longer to prevent the disease from coming back.

Surgery may sometimes also be required to remove specific abscesses from the body, especially if a patient is not responding to antibiotic treatment.

Smart scales, also known as body fat scales, not only measure your body weight and Body Mass Index (BMI), but also provide a breakdown of your body composition and how it changes over time. They look and function in a very similar way to analog bathroom scales, but unlike their traditional counterparts, these devices can connect to your phone and send measurements to a range of connected fitness apps.

Some of the best smart scales on the market can give you an in-depth explanation of your health stats, offer basic diet advice and even measure your heart rate. Their functionality outstrips that of analog devices by a long mile.

What are the potential benefits of using a smart scale?

Smart scales are not just for fitness enthusiasts and can benefit a wide range of population groups, Dr. Michael Chichak, a general practitioner and clinical reviewer at MEDvidi, a health clinic based in San Jose, California, told Live Science by email. "These include athletes who track muscle mass for improved performance and recovery, elderly individuals who need to monitor changes in bone density and muscle mass to avert complications associated with sarcopenia [age-related loss of skeletal muscle] and people suffering from chronic conditions like heart diseases or diabetes where body composition can affect the management strategies of these conditions," Chichak said.

However, smart scales should not be treated as diagnostic devices, he emphasized. They are not as accurate as clinically validated diagnostic methods, such as the “gold standard” Dual Energy X-ray Absorptiometry (DEXA), which uses rays of ionizing radiation to penetrate the body and produce images of bones and soft tissues inside. Moreover, plenty of factors can affect the accuracy of smart scales, from the make of the device to hydration levels and foot placement, Chichak said.

That is because most smart scales work using bioelectrical impedance analysis (BIA). While this method has its perks — it is non-invasive and relatively cheap, for example — it is also prone to distortions, according to a 2014 review published in the International Journal of Clinical Nutrition.

How does bioelectrical impedance analysis work?

BIA works by sending a small, unnoticeable electrical current through your body (often through bare feet and/or hands) and measuring your body's impedance, or resistance, to this current. Tissues with high water content can transmit electric currents more easily than tissues with lower water content. This means that muscle and blood will pose less resistance to electricity than fat and bones, for example. Then, a smart scale feeds these measurements into its proprietary algorithms (often incorporating self-reported metrics like age, sex and height) that calculate your body composition. The accuracy of results depends on how well a device measures resistance and which equations it uses to interpret this data, the review authors noted.

In that regard, some commercially available smart scales leave a lot to be desired, according to a 2021 study published in the journal JMIR Mhealth Uhealth. Scientists compared the measurements obtained with three different models of smart scales with DEXA and found that these devices can underestimate both fat and muscle mass by as much as 8 kg and 8.03 kg (approximately 17.6 pounds), respectively. Studies have also shown that typical stand-on smart scales tend to be less accurate than devices that use foot-to-hand technology (a stand-on platform and handles), according to a 2022 review published in the European Journal of Applied Physiology.

When using a device where you just step on the scale with bare feet, the current skips over the waist and above, Dr. Claudia Dal Molin, a sports medicine physician and an assistant professor of medicine and orthopaedics at the University of Maryland School of Medicine, told Live Science by email. "In a woman, where more fat may be in the thighs than the mid-section, this technique could over-represent her body fat percentage, whereas in a man with less fat in the thighs, this might give a more accurate result," Dal Molin explained.

However, that does not mean that foot-to-hand technology is automatically better. "Even in products that use a handle to better include the upper body in the measurement, companies may not provide transparent information about what algorithms are used to give you their final measurements," Dal Molin said.

What other factors can affect the accuracy of a smart scale?

As we mentioned before, how and when you take measurements may also affect the accuracy of your smart scale’s readings. Dehydration, excess body water and even skin temperature may alter electrical resistance in the body. For example, one 1988 study has shown that BIA can overestimate body water content and underestimate body fat percentage when the measurements are taken in warm ambient temperatures.

The good news is that science has moved forward since the late 80s. "The latest designs with bioelectrical impedance technology have improved the accuracy of the measurements of body fat and muscle mass," Chichak said.

For example, some high-end smart scales use multiple frequencies of electrical current to improve accuracy. These devices measure impedance in different body segments, such as the arms, legs and torso, so they can provide a more detailed analysis of body composition, according to a 2024 study published in the journal Frontiers in Nutrition.

The takeaway? Home scales can still allow us to appreciate trends fairly accurately, but it is important to understand that BIA measurements are data points that can be flawed, Dal Molin said. "Lastly, few smart scales are studied for accuracy and many studies have small sample sizes. Our knowledge within specific brands and products is therefore even more limited," she added.

This article is for informational purposes only and is not meant to offer medical advice.

Now, a new study suggests that marathons also affect the brain — causing the organ to eat itself to make up for fuel lost during the run.

In the research, published March 24 in the journal Nature Metabolism, scientists observed declines in a key biomarker of myelin, a fatty tissue that insulates the connections between brain cells, in marathon runners just after a race. The study authors say this suggests the brain consumes myelin as an energy source under these extreme conditions.

Luckily for long-distance runners, these effects appear to be reversible.

Related: 6 ways an athlete's brain differs from an average person's

Once the body has exhausted the supply of its standard energy source — glucose, or sugar — it turns to backup generators, metabolizing fats as an alternative fuel source. The brain is, metabolically speaking, more of a Humvee than a hatchback; the energy-hungry organ devours 20% of the body's energy, meaning it can quickly suffer damage if fuel sources run short.

Pedro Ramos Cabrer — a neuroscientist at CIC biomaGUNE, a nonprofit research institute in San Sebastian, Spain, and a co-author of the study — told Live Science that he and his colleagues wanted to identify the brain's reserve energy sources. They suspected that fatty myelin could be the answer. Previous research in rodents suggested that fatty acids produced from myelin breakdown could help boost cell survival in the brain. Whether these preclinical findings would be replicated in humans was still a mystery, though.

"We needed to really deplete all the sources of energy of a body to prove this," Cabrer told Live Science.

The team scanned 10 runners' brains 48 hours before they ran a marathon and then again two days, two weeks and two months afterward. They used MRI, which can reveal the presence of water molecules trapped between myelin layers.

The brain scans showed that, two days post-run, the MRI signals in 12 brain areas were depleted compared with before the race — in some cases, by up to 28%. Changes to the brain's overall myelin levels were not statistically significant, however, suggesting that any changes were very isolated to specific regions.

"The areas that we saw have more significant changes were those related to motor circuits and the center of emotional control of the brain," Cabrer said. He suggested that this reflects the mental and physical effort the brain must maintain to get through a marathon.

For any runners concerned about this cerebral cannibalism, there's good news: After two months, all of the runners' myelin measures had recovered to their baseline levels.

Klaus-Armin Nave, director at the Max Planck Institute for Multidisciplinary Sciences in Germany, was not involved in the study but has also studied how myelin stores energy, using lab mice. Nave said the paper's findings aligned with how neuroscientists think myelin is maintained in the brain.

Related: How far can a person run without stopping?

"Myelin is constantly made and degraded," he said. "It's like a bathtub in which you constantly fill in water and constantly drain it." He added that Cabrer's work presents "very strong evidence" that, after a marathon, the brain's metabolic needs increase. Thus, the fuel stored in myelin is depleted more quickly than usual, leading to brain shrinkage.

The findings don't mean runners should avoid marathons on their brains' behalf. Both Nave and Cabrer noted that the study's small size means more work will be needed to draw concrete conclusions about marathons' effects on the brain. The very limited effects on overall myelin also raise the need for further research, they added.

Nevertheless, these effects may carry increased risks for certain athletes. For example, in people with amyotrophic lateral sclerosis (ALS), metabolic molecules typically made by myelin are in short supply, and the researchers think that excessive exercise could potentially exacerbate the problem.

Further research will be needed to confirm this theory, Cabrer said.

Its specifications are impressive for the price. The Morento MR5866 features three different air filters, two air inlets and coverage of up to 1,290 square feet (120 square meters). Plus, it comes with a dedicated app, voice control and an air quality monitor, and it can be connected to Amazon Alexa and Google Assistant.

This air purifier is slightly more advanced than the Morento HY4866 Air Purifier, a model we rated at a solid 4 out of 5 stars about a year ago, so our expectations were high.

Morento MR5866 Smart Air Purifier review

Morento MR5866 Smart Air Purifier: Design

• Light, compact and portable
• Boxy, dull-looking design
• Available in three colors

The Morento MR5866 Smart Air Purifier is available in three colors: white, gray and black. Our testing unit came in white, which is perhaps why its appearance did not score highly in our books. We were also somewhat underwhelmed by its chunky shape. True, this inoffensively basic design may blend in with various home decors easily, but it lacks the uniqueness and character of some of the more premium models. If style is high on your priority list, the Morento MR5866 may not be the best choice for you.

Looks aside, it is quite a well-designed air purifier. The Morento MR5866 weighs just 9.92 pounds (4.5 kg) and comes with a small handle at the back of the unit, so it is easy to move around even with one hand. It is also very compact. This air purifier measures only 17.7 inches (45 cm) in height and 13.6 inches (34.5 cm) in width, making it a good option for desktops and tight spaces.

Unlike most air purifiers, the Morento MR5866 has not one but two air inlets, one at the front and the other at the back of the unit. This means it requires two sets of air filters, each consisting of a pre-filter that captures hair, dust and other large particles, a HEPA filter that traps airborne pollutants as small as 0.3 microns, and an activated carbon filter that helps reduce bad smells and VOCs (volatile organic compounds.)

While this dual-layer design may sound expensive to maintain, that is fortunately not the case. On the contrary, a two-pack of filter replacements costs a very reasonable $23.99 — much cheaper than similar filter replacements from other air purifier brands. In that regard, the Morento MR5866 offers excellent value for the budget-conscious.

Morento MR5866 Smart Air Purifier: Features

• Three fan speeds, auto mode and sleep mode
• Compatible with Amazon Alexa and Google Assistant
• Limited air-quality monitoring

The Morento MR5866 air purifier can be controlled manually using a small touchscreen located at the top of the unit, or remotely via the Havaworks app. Plus, it can be connected to Amazon Alexa and Google Assistant, so it also comes with voice control. In terms of smart features, this air purifier lived up to our expectations. Our Morento MR5866 swiftly connected to third-party devices and we did not experience any connectivity issues during testing.

The Morento MR5866 has three manually adjusted fan speeds, an auto mode, sleep mode and timer, so you can schedule its working hours in advance and leave it to regulate its fan speed based on air quality readings. This air purifier features a built-in air quality monitor and its measurements are displayed in the app and on the unit's control panel.

However, the Morento MR5866 can only track airborne particles that measure at least 2.5 microns. While this accounts for many common pollutants like dust, pollen and some mold spores, it does not include any smaller particles, of which there are plenty in the indoor air — the aforementioned VOCs, for example. We were also disappointed that the Morento MR5866 shows only real-time air quality measurements, meaning we could not track changes over time.

Morento MR5866 Smart Air Purifier: Performance

• Good air-cleaning performance
• Quiet even at high fan speeds
• Fans take time to get up to speed

On the whole, the Morento MR5866 air purifier delivers good performance for the price. However, we think it is better suited to small- and medium-sized rooms than large spaces, for which it is often advertised. This air purifier takes a full hour to filter out the air in a room measuring 1,290 square feet (120 square meters), but only 12 minutes in a room that is only 219 square feet (20 square meters). This corresponds with our experience — the Morento MR5866 made a tangible difference to the air quality in our relatively small bedroom, but its effects were less noticeable in larger spaces.

To fully assess its air-cleaning capabilities, we conducted a series of performance tests using a Perfect Prime air particle monitor, a professional device capable of detecting airborne pollutants as small as 0.3 microns. We started with an ambient air quality test: We put the Morento MR5866 in an enclosed medium-sized room, measured baseline air quality and then ran it on auto mode for 30 minutes. It removed 87.8% of 0.3-micron particles, 91% of particles measuring 2.5 microns and all pollutants larger than 10 microns. These numbers are not too impressive — other air purifiers in this price range can deliver better results.

That said, the Morento MR5866 managed to redeem itself during our smoke tests. We burned matches and incense sticks to create different types of heavy pollution, then measured the changes in air quality before and after running the air purifier for 30 minutes. We conducted several tests on the maximum fan speed and auto settings, and on average, the Morento MR5866 achieved an 86% reduction in 0.3-micron particles, a 97% reduction in 2.5-micron particles, and a 99.5% decrease in particles measuring 10 microns or more. While it is not the most powerful air purifier we tested, it still delivers a good air-cleaning performance for the price.

We also liked how quiet it was. We measured how loud the Morento MR5866 was at different fan speeds using a Sound Meter decibel-counting app, and we did not get a measurement higher than 58 dB — equivalent to the sound of a quiet conversation. At its lowest fan speed, we could barely hear it working.

Our only grumble about this air purifier is that it has underpowered fans. When switching between different settings, they take quite a long time to get up to target speed. For example, it can take more than 15 seconds for the Morento MR5866 to switch from the lowest fan speed to the fastest. For comparison, more premium models can do that in as little as five seconds. This delay could be reducing its overall performance.

Morento MR5866 Smart Air Purifier: User reviews

Amazon's customer reviews place the Morento MR5866 at a 4.5 out of 5 stars rating, with 79% of users giving it a full five stars. Positive reviews praised this air purifier for its compact design, quiet fans, wide app compatibility, ease of use and good value for money.

As one happy user commented: "I’m very satisfied with this air purifier’s performance. While it truly shines in smaller rooms, it still makes a noticeable difference in larger spaces, helping to improve overall air quality. [...] The noise level is low on standard settings, and while higher speeds are slightly louder, it’s definitely nothing that would keep you awake. And if you are very sensitive to sound, it has a “night mode” which is almost impossible to hear, it makes the operation quiet enough that I sometimes have forgotten it was even on. [...] For the price, it’s a fantastic option that I’d wholeheartedly recommend!"

Negative reviews, on the other hand, often revolved around individual faulty units and network-related app issues that render the air purifier "unusable." As one user said, "As far as an air purifier, it does a good job. The issue is, it continuously shuts off by itself, it beeps intermittently and changes settings by itself. It is frustrating having to keep turning it on. The instructions blame it on other signals over the wireless network."

Should you buy the Morento MR5866 Smart Air Purifier?

✅ Buy it if: You are looking for a smart air purifier on a tight budget. For as little as $79.99, the Morento MR5866 does a good job of trapping airborne pollutants without being too noisy or taking up much space. Plus, it connects to a range of smart home apps and does not require costly filter replacements.

❌ Don't buy it if: You want cutting-edge performance and advanced air quality monitoring. The Morento MR5866 will not help you identify the sources of air pollution in your home, and its air-cleaning capabilities fall slightly behind some of the more premium models.

If Morento MR5866 Smart Air Purifier isn't for you

The BlueAir Blue Pure 411i Max is a great alternative to the Morento MR5866. It is just as quiet, compact and affordable, and it comes with a similar array of smart features, but it looks more stylish and offers more powerful air-cleaning capabilities.

If you would rather stick with the same brand, consider the Morento Air Purifier HY4866. Its looks and performance closely match the Morento MR5866, but it tends to be cheaper by around $50.

Looking for something bigger and more powerful? Then you can't go wrong with the Levoit Core 600S. It is one of the best air purifiers on the market for functionality and air-cleaning performance, but it will set you back by around $299.99.

Morento MR5866 Smart Air Purifier: How we tested

We spent over two weeks testing the Morento MR5866 Smart Air Purifier, looking at its design, functionality, day-to-day performance, ease of use and value for money. We also measured how loud it was using a Sound Meter decibel-counting app and conducted a series of performance tests using a Perfect Prime air particle monitor, a professional-grade device that can detect airborne pollutants as small as 0.3 microns.

We started with an ambient air quality test: we put the Morento MR5866 Smart Air Purifier in an enclosed, medium-sized room and ran it on auto mode for 30 minutes, taking note of air quality changes every 15 minutes.

Next, we performed several smoke tests. We burned matches and incense sticks to create different types of heavy pollution, then measured the air quality before and after running the air purifier for 30 minutes. The smoke tests were conducted on auto settings and at the highest fan speed.

The symptoms: The patient was initially brought to the emergency room after he was found collapsed in his home. Tests showed he had severe metabolic acidosis, in which too much acid builds up in the blood. Further labs, as well as CT scans and a review of the patient's medical history, suggested the buildup was caused by a lung infection, kidney injury and, potentially, heavy drinking, as the patient had a history of alcohol dependence.

The patient later tested positive for COVID-19 and a bacterial infection. Given the complexity of the case, he ultimately spent over a month in the intensive care unit (ICU) before being transferred to a general hospital ward to fully recover. Toward the end of his ICU stay, he had started having diarrhea. His doctors put him on a probiotic that they thought would ease the symptoms, and he continued taking that probiotic in the general ward.

But then, after nearly two months of treatment, the man suddenly developed swelling and "severe, continuous" pain in his abdomen. Tests again revealed a high level of acid in his blood, and scans showed signs of nonocclusive mesenteric ischemia, a dangerous condition in which the intestines don't get enough blood.

What happened next: While investigating the man's symptoms, the medical team took a blood sample that tested positive for a bacterium called Clostridium butyricum — the same bacteria contained in the probiotic supplement he'd been taking. A genetic test confirmed that the strain in the man's blood perfectly matched the probiotic strain.

The diagnosis: The man had contracted a blood infection from the bacteria in his probiotic — a condition known as probiotic-related bacteremia.

The treatment: Unfortunately, the patient's condition rapidly progressed to multiorgan failure, and he became too unstable for the doctors to consider surgical treatment options. "His treatment was transitioned to palliative care and he died on the 60th hospital day," his doctors wrote in a report of the case.

What makes the case unique: Probiotic-related bacteremia is a known risk of taking probiotics, but it is rare. Having a weakened immune system or abnormalities in the gastrointestinal tract can raise the risk of these blood infections.

When they do occur, the infections are seen most often in older adults with multiple medical conditions. In the man's case, he had a history of alcohol dependence, smoking, colon cancer, high blood pressure and chest pain due to heart disease, along with the conditions that caused his initial trip to the ER. The report didn't note how recently the man had had cancer or if he'd undergone chemotherapy, which can suppress the immune system.

While being treated, he'd also been given a steroid to tamp down the inflammation driven by his COVID-19 infection, and steroidal drugs suppress the immune system. This may have further increased the likelihood of developing a bloodstream infection from a probiotic.

Notably, this is not the only case of this particular strain of C. butyricum causing probiotic-related bacteremia.

The probiotic is widely used, especially in Japan, and generally has a good safety profile. It's given in hospital settings as a diarrhea treatment, in part because it's thought to make the gut less favorable to pathogens and more favorable to bacteria that aid digestion and help mitigate inflammation.

Antibiotics, which the man was given for his bacterial infection, can also deplete the gut of bacteria, and probiotics can help restore some of those lost microbes. But in medically unstable and immunocompromised patients, these probiotics can occasionally go rogue, the doctors warned in the case report.

The unnamed Michigan resident received the kidney transplant at the University of Toledo Medical Center (UTMC) in Ohio, in December last year, Michigan Department of Health and Human Services (MDHHS) spokesperson Lynn Sutfin said in a statement, the AP reports. They died in January 2025.

This marks the first human case of rabies in Michigan since 2009. "Person-to-person transmission of rabies is extremely rare, though it has been documented in a very small number of cases involving organ transplantation," a statement from UTMC reads, as reported by local news WTOL 11.

Rabies is a deadly disease caused by the rabies virus that affects the central nervous system of mammals, including humans. The virus is typically transmitted through the saliva of an infected animal via bites and open wounds, such as scratches.

Related: Can you transplant an organ more than once?

Rabies is almost always fatal once symptoms appear. The time it takes from exposure to symptoms appearing varies from weeks to months, but symptoms usually occur sooner when the wound is closer to the brain. Symptoms initially resemble the flu (fever, headache, weakness) but progress to neurological issues such as confusion, hallucinations, paralysis, hydrophobia (fear of water), and eventually coma and death. Fewer than 20 people have ever survived rabies after symptoms presented, according to the Centers for Disease Control and Prevention (CDC). Around 10 people die from rabies in the U.S. each year, the CDC estimates.

According to the CDC, the vast majority of U.S. rabies cases are a result of exposure to bats, raccoons, skunks and foxes. In the U.S., 7 out of 10 people who die from rabies are infected by bats, while worldwide, domestic dogs cause over 95% of the estimated 70,000 annual human rabies deaths.

The Michigan resident's rabies was confirmed by the CDC Rabies Laboratory. In a statement, the CDC said that the organ donor was exposed to rabies from a wild animal in Idaho five weeks before they died and their organ was transplanted, ABC News reports. The donor had not died with "traditional rabies symptoms," and they had not sought out medical help or notified public health officials after their exposure to the animal.

After an animal bite, rabies can be prevented with post-exposure prophylaxis (PEP). This includes immediately washing the wound with soap and water for at least 15 minutes, and receiving four or five doses of the rabies vaccine over the course of 14 days after the bite. The vaccine helps the immune system produce antibodies against the rabies virus. If the person has never been vaccinated against rabies, they will also receive rabies immune globulin (RIG) on the day of the bite, which provides immediate passive immunity while the vaccine triggers the body's own immune response.

About 800,000 people receive rabies-related medical care from local or state health departments around the U.S. every year.

Several cases of rabies being contracted from a transplanted organ have been reported in the past. A 2005 study in the New England Journal of Medicine reported that four recipients of kidneys, a liver, and piece of an artery died as a result of the donor having contracted rabies from a bat, and a 2020 study in the journal Transplantation revealed that a 5-year-old girl and another recipient died of rabies after a kidney transplant.

Other organ recipients saved

"In addition to the organ donor's kidney, doctors implanted corneal grafts from the donor's eyes into three different patients in three states," the latest CDC statement read. "Based on the concerning symptoms of the kidney recipient who died, CDC worked with Missouri health officials to intercept a fourth corneal graft before it could be implanted into a Missouri resident."

All of the patients who had received transplants of the donor's corneal tissue have since been given rabies post-exposure prophylaxis shots and are in good health, the CDC says.

Cases like this are still extremely rare and should not discourage patients from receiving life-saving organ transplants, Dr. Daniel Kaul, a clinical professor at the University of Michigan's Infectious Disease Clinic who was not involved in the treatment, told local broadcaster WOOD TV8. "The risk of not getting a transplant if you have organ failure is so much higher than this kind of incredibly rare but tragic situation," he said.

While organs are screened ahead of transplantation, testing for rabies and other rare diseases would take several days, whereas donated organs are only viable for transplantation for a matter of hours, Kaul added. However, donors are excluded if they report having rabies or show any visible symptoms of rabies infection.

The MDHHS noted that all health care providers and anyone else exposed to the Michigan transplant patient have been assessed for rabies exposure and given PEP if necessary.

So how much of your brain do you really need to survive?

Neuroscientists are still investigating this question, and there likely isn't a black-and-white answer. How well a person fares after experiencing brain damage — or when they're missing a part of their brain altogether — can depend on a multitude of factors, such as the region of the brain that was affected, how and why the brain region was affected, and how old they were when they experienced the brain damage. But just how much of your brain you can live without and function normally may surprise you.

Normal life with an abnormal brain

Take the case of EG, a woman who goes by her initials to protect her privacy. When EG went in for an unrelated medical scan, she discovered she was missing her entire left temporal lobe, a large section of the brain that is located near the ear and is responsible for auditory processing, memory and language. Doctors believe the abnormality stemmed from a cyst (a fluid-filled sac) that developed early in her childhood and caused brain damage.

Despite missing a large chunk of her brain, EG was living a totally regular life. While the left temporal lobe houses some of the brain's crucial language centers, she could read normally, had a better-than-average vocabulary, and even spoke Russian as a second language.

Evelina Fedorenko, an associate professor of brain and cognitive sciences at MIT, found that EG's brain had rewired itself to account for the missing region. Whereas language-related tasks would light up the left temporal lobe in people with typical brains, language-related neural activity had moved over to the right side of EG's brain.

Related: Could we ever retrieve memories from a dead person's brain?

Living with half a brain

The brain is so flexible that some people can even live without half of it. Dr. William Bingaman, a neurosurgeon at Cleveland Clinic, has performed over 500 hemispherectomies, surgeries where one side of the brain is disconnected in an operation. Hemispherectomies are generally performed for severe cases of epilepsy that don't respond to other treatments.

In this procedure, surgeons disconnect the nerve fibers that connect one side of the brain to the other and to the rest of the body, which functionally stops that side of the brain from working. The disconnected hemisphere is left in place because removing it requires a riskier surgery with more potential complications.

The recovery process for these surgeries can be intense, but many patients go on to regain function. One of Bingaman's patients, Mora Leeb, had 50 seizures a day as an infant. She quickly became a candidate for hemispherectomy, and after undergoing the surgery at 9 months old, she reverted back to the skills of a newborn.

Mora had to relearn how to smile and roll over, and progress from there was slow. But with the help of therapists, she was able to develop her speech and motor skills. Now a teenager, Mora still speaks and processes language slowly, but it's clear that the remaining half of her brain has taken on the functions of the missing side.

Bingaman said although the surgery is straightforward, doctors still don't understand exactly how their patients recover so well.

"I've had hemispherectomy patients go to college, get married, have children, have a family, and be cognitively completely normal with one side of the brain," Bingaman said. "How that happens? We don't understand it."

The brain parts you can't live without

There are parts of the brain Bingaman won't touch, though. For example, he doesn't disconnect the brain stem, the thalamus or the basal ganglia. These are structures deep inside the brain that are responsible for the basic functions of breathing and heart rate, sensory processing, and motor control, respectively.

These structures are essential for survival.

"Brain stem strokes will kill people most of the time," Fedorenko said. Strokes or injuries that people do recover from tend to occur in the outer layer of the brain, called the cortex. The age of the person when they experience brain damage can also play a big role in the degree of their recovery.

"In general, the earlier you have brain damage, the better off you are," she said. Hemispherectomies have better outcomes in children under 2 years of age, for example. One exception to that rule is damage to the cerebellum, a region of the brain that's essential for movement, balance and coordination. Cerebellar damage in children tends to lead to more severe issues, she said, because it grows rapidly during childhood and plays a key role in many stages of development.

Even still, there have been a few documented cases of people missing their cerebellum. One woman made it into her 20s before learning she had been born without a cerebellum, though she did have problems with both speech and movement. It's actually possible that more people have atypical brains than scientists realize; many brain abnormalities are caught only during unrelated imaging tests.

With all of these cases in mind, Fedorenko said it's time to widen the "error bars" when it comes to thinking about how well a person can function with an atypical brain.

"There's a lot of knowledge we're lacking still about brains that look very different from a typical brain but can sustain human cognition just fine," Fedorenko said.

Brain quiz: Test your knowledge of the most complex organ in the body

But what if the results of that research were misconstrued, with the devil lurking in the fine details that most people do not read or do not understand?

Neuroscience research going back to the early 1980s claimed to demonstrate that conscious free will is an illusion ("conscious free will" refers to our conscious decisions determining our actions). These results accumulated like nails in the coffin of free will, offered up by neuroscientists and hammered in by the mainstream media, until, in 2016, the Atlantic declared, "There's no such thing as free will."

Not so fast. More recent studies, combining empirical data and computational modeling, suggest this prior research had been misinterpreted, and none of it bears on conscious free will one way or another. Neuroscience, we conclude, has not disproven conscious free will.

Many cognitive neuroscientists in the field, including former "no-free-will" proponents, now acknowledge that the supposed neuroscientific evidence against it is dubious. Unfortunately, the public still hasn't heard the news, and the idea that neuroscience has disproven conscious free will, or even free will in general, still hangs in the air.

Once the sole purview of philosophers, free will and consciousness have been increasingly studied by neuroscientists. These topics differ from other areas of study in neuroscience in that they matter deeply to most, if not all, of humanity. In contrast, few would lose sleep over the relative importance of other human attributes, such as whether people can directly sense magnetic fields (magnetoreception).

Related: People who can't 'see with their mind's eye' have different wiring in the brain

Science often moves forward by posing hypotheses that are later modified or rejected. Given the deep existential nature of research on volition, however, we face two very important questions: Where should we set the bar for evidence claiming to bear on free will? And how should we evaluate and interpret such evidence to know if or when it has been met?

Recognizing what philosophers of science call "inductive risk," or the costs of potential errors, we should set the bar high. The cost of mistakenly denying free will is considerable, as those troubled letters we received show. And there is good reason to doubt the evidence often cited. The neuroscience of volition typically focuses on immediate (or proximal) and meaningless decisions, (like "press the button from time to time, whenever you feel like it, for no reason at all"). The decisions we care about with respect to free will and responsibility, however, are ones that are meaningful and often have longer time horizons. Perhaps many, or even most, of our day-to-day decisions — choosing when to take the next sip from your water cup or which foot to put forward — are not acts of conscious free will. But maybe some decisions are. Fortunately, or unfortunately, those consequential ones are the most difficult ones to study.

What would it take for neuroscience to disprove conscious free will? The evidence must clearly show that people settle on a decision unawares. Here the devil is indeed in the details of predicting behavior and inferring consciousness from brain activity. For example, using machine learning to "predict" behavior in advance of the conscious decision will not necessarily tell us much. Consider a simple free choice of pressing a button with your right hand or your left hand, where predictions that are about 60 percent correct might be statistically significant (compared with a coin toss of roughly 50 percent); such predictive power would not undermine conscious free will.

Why not? Because a 60 percent accurate prediction might just pick up on a tendency toward one alternative or the other rather than a firm decision. Moreover, many of us have enduring preferences and character traits that affect some decisions, and it would be surprising if such choices were not at least somewhat predictable in advance based on brain activity. In addition, because consciousness and decision-making play out over time and rely on past experiences, prediction need not indicate determination. Thus, in such cases, the details of performance of the machine-learning classifier do matter, not just whether it is "significantly above chance." In fact, anything less than close-to-perfect predictive accuracy may be equivocal.

In addition, neuroscience results depend on their data-analysis method, which can mislead. For example, some digital data filters can, in effect, "leak" future information into the past, and analyses involving a sliding window can inadvertently allow the system's data analysis to "peek" into the very future that it is trying to predict. The devil, again, is in the details.

These considerations matter because new scientific data on free will are on the horizon, mainly because of the proliferation of invasive recordings from surgically implanted brain electrodes in humans. An informed reader needs to know what evidence would truly falsify conscious free will and what would not.

To be clear, we are not arguing for or against the existence of conscious free will; we are talking about the data here and the way to know whether those data constitute evidence that undermines conscious free will. We must ensure that the paradigms that we investigate in neuroscience allow us to draw conclusions about the actions that pertain to conscious free will. For many behaviors, being predictable to some degree should not surprise us: Does it undermine your free will if we predict that you will brush your teeth before going to bed tonight?

The neuroscientist Robert Sapolsky has taken a different approach. He discounts the brain data and instead focuses on statistical regularities — for example, that early-childhood adversity can negatively impact the kind of choices we make and outcomes we experience later in life. He argues in his book Determined that we are part of a deterministic world over which we have no influence and that statistics like the childhood adversity findings bear this out. We do not deny the reality of regularities; our actions today may indeed be constrained (or partly determined) by our past environment or experiences. But just how much constraint is enough to rob us of free will? The lack of very high predictability in those statistics leaves plenty of room for acts of conscious free will (again, it would be strange if your early life experiences had no effect whatsoever on your later life).

Finally, we note that a single human brain is arguably far more complex than the entire Earth's atmosphere, and we can't even predict the weather more than a few days into the future. So throwing sophisticated AI at brain data is unlikely to enable us to predict future brain states based on past ones, at least any time soon. We leave open the possibility that we will get there one day (though you are free to disagree). But one thing is clear: we are not there yet.

This is an opinion and analysis article, and the views expressed by the authors are not necessarily those of Scientific American.

This article was first published at Scientific American. © ScientificAmerican.com. All rights reserved. Follow on TikTok and Instagram, X and Facebook.

This phenomenon occurs when the moon passes between the sun and Earth and partially blocks the sun, making it look like a bite has been taken out of our nearest star.

But staring directly at the sun without certified eclipse glasses can lead to an eye condition known as solar retinopathy, which can cause permanent vision loss.

So what is solar retinopathy and how can you protect yourself against it?

Related: How to watch tomorrow's sunrise 'devil horn' solar eclipse online for free

What is solar retinopathy?

Solar retinopathy occurs when intense light causes damage to the light-sensitive tissue in the retina.

The retina detects light and converts it into signals that the brain translates into the images that you see. Despite its name, solar retinopathy can be caused by any intense light source, including the sun, a laser pointer or the bright light from a welding torch. Solar retinopathy can occur within seconds of exposure to intense light in one, or more often, both eyes.

Anyone who stares at the sun, even on a regular day, can get solar retinopathy, Dr. Julie Rosenthal, a clinical assistant professor of ophthalmology and visual sciences at the University of Michigan, told Live Science. However, the eclipse is a time that those of us who don't weld or use lasers can easily get exposed to this kind of damage, she said.

People may be particularly vulnerable to solar retinopathy during a partial eclipse because the dark conditions caused by the sun being partly covered prevent the protective reflexes in the eye from properly kicking in, Live Science previously reported.

When it's light outside, for instance, people tend to squint their eyes while their pupils — which control how much light enters the eye — constrict to protect the retina, Dr. Sandra Montezuma, a professor of ophthalmology at the University of Minnesota, told Live Science. However, when it's dark, the pupils dilate, allowing more light to enter the eye and potentially damage the retina, she said.

Typically, people will not feel the damage happening as they stare at the sun as there are no pain receptors in the retina.

What are the symptoms of solar retinopathy?

A common symptom of solar retinopathy is blurred vision, often with a big blurred spot in the middle of your field of vision. Patients may also have distorted vision, for example seeing straight lines as being curved or perceiving objects as smaller than they actually are.

Other symptoms include headaches and changes in color vision when color-sending cells are damaged. Solar retinopathy can also cause a blind spot in a patients' line of sight. People may also complain that their eyes feel watery or sore.

The longer and more directly you look at the sun, as well as the more often you do it, the greater the damage. Symptoms of solar retinopathy may take hours or days to emerge after injury.

An eye doctor can image the retina to diagnose solar retinopathy, and to determine how much damage has been done to your retina.

Is solar retinopathy treatable?

There is no treatment for solar retinopathy, however, the condition will improve for many people during the first six months after damage occurs, Dr. Rosenthal said. Nevertheless, even if a patients' symptoms and vision problems get better over time, many may still have a permanent dark spot or see some wavy lines in their vision, she added.

In some cases, the retina may be so severely damaged that it does not repair itself. This can leave patients with permanent vision loss.

How can you prevent solar retinopathy?

The best way to avoid solar retinopathy is to not look directly at the sun, Dr. Montezuma said.

However, if people still want to view the partial solar eclipse on March 29, then they should ensure that they are either wearing solar eclipse glasses that comply with the ISO 12312-2 international standard, or using solar filters on skywatching equipment, she added. Solar filters are specialized filters that are added to equipment such as telescopes, binoculars or cameras that block sunlight.

If you don't have access to any of these things then another safe option is to just watch the partial eclipse online, Dr. Montezuma said.

"It's really a great time to be a part of science and to enjoy this cool phenomenon, but just make sure you're doing it safely," Dr. Rosenthal said.

Although on first use the watch felt difficult to navigate around, once you're used to it, it is very simple with a clear main menu and no frills. You don't get overwhelmed and, with limited customization options, things are kept simple, making it ideal for smartwatch newbies. Plus, we found the stats to be reasonably accurate, so for a budget fitness tracker it performed well.

Overall, the Xiaomi Watch 2 is a good purchase for those wanting to try out a budget fitness tracker but it isn't the best fitness tracker. We loved the more traditional look of this watch and found it incredibly comfortable to wear, day and night. The only downside is the short battery life.

Xiaomi Watch 2 review

Xiaomi Watch 2: Design

• Large, bright screen with colorful visual displays
• Secure charging dock
• Comfortable, changeable strap

The Xiaomi Watch 2 has a large, round 1.43-inch (3.6 cm) AMOLED display screen and, with the body being made from aluminum alloy, it is super lightweight weighing only 1.3 oz (36.8 g) without the strap. The version we tested had a leather strap, although this is changeable, with a skin-friendly TPU and a recycled braided strap being the other options. We found the strap comfortable to wear but it did tend to slip down our wrist more than when wearing a silicone strap.

The large screen makes it easy to see your workout stats, and although it looks big, it didn't get in the way during workouts or when sleeping. The buttons on the side are flush to the bevel, so they didn't catch on our clothing or rub against the skin during yoga, for example. And the screen remained bright during our swims, allowing us to check our lengths and pace under the bright artificial lighting and even remaining clear underwater.

While the screen is large, the visuals are even better with colors remaining bright during the daylight. With the large screen, workout stats are clear and the screen remains uncluttered. Offering bright visuals and graphs alongside numbers for your workout statistics, the Xiaomi Watch 2 has a great-sized screen to display it all. And while the screen's brightness is a welcome addition during daylight hours, once it is on "Do not disturb" it didn't wake us during sleep.

The touchscreen was generally responsive, but it wasn't as responsive as other smartwatches we've tested. We also found it to be less responsive after swimming, although this was only temporary. We didn't experience much lag overall with this screen.

There are two buttons on the right-hand side. The top button allows you to access the main menu and then locks the screen again. The lower button acts like a "back" button, taking you to the screen you were last on. This means you are reliant on the touchscreen a lot of the time, so its responsiveness is quite important.

We wore this watch for several days at a time before it needed charging (more on that below) and found the screen to cope with smudges and dirt well. The screen itself didn't scratch, but annoyingly, the bezel did chip easily, and we noticed a little dent on the edge.

The Xiaomi Watch 2 is customizable to an extent, allowing you to change the view of the apps and the clock faces. However, unlike other smartwatches we've tested, you can't alter the widgets you see when swiping left or right. Swiping left or right acts like a shortcut to the weather, workout modes, sleep data, heart rate and blood oxygen level. We couldn't find a way to customize which shortcuts you see.

We didn't find the Xiaomi Watch 2 as easy to use as other smartwatches: Some of the functions seemed unintuitive, and the watch felt clunky to navigate around. We did like the top button giving direct access to the main menu, but the layout and functions seemed a bit basic, with swiping left or right offering shortcuts and not much else. However, once you're used to the Xiaomi Watch 2 for a while, it becomes easy and obvious how to use it.

While the main focus is on the workout modes and health monitoring stats, the Xiaomi Watch 2 has extra functions such as cycles, allowing you to monitor your period via the app, sleep monitoring, stress measuring, breathing techniques and more. This watch allows you to gain a better view of your overall health rather than just focusing on workout statistics, and can be an aid in calming your nervous system, which will ultimately benefit your overall health.

We particularly liked the charging dock on this watch. It sits comfortably into a "bed," meaning once connected, it is unlikely to get nudged and stop charging. One thing that did let this watch down was the battery — only lasting two to three days, at a push. However, it was quick to charge from completely flat to full in an hour. Overall, though, the design of this watch was good with little left to be missed.

Xiaomi Watch 2: Performance

• Good accuracy for stats
• Poor battery life
• Not a user-friendly interface

Getting workouts started on the Xiaomi Watch 2 is simple, either by swiping left or right to access the shortcut or, as we preferred, clicking the top button to access the main menu. Once you've found your workout mode from the hundreds available, simply click on it and press 'Go'. It's that easy to get started.

It also has an auto-detect function so if you forget to start a workout, the watch will give you a nudge and suggest what it thinks you might be doing. We tested this a few times when out walking and it guessed right. ]

You can also sync your music to this smartwatch, allowing you to control the soundtrack to your workout through the media player. Unfortunately, when in a workout mode, there isn't a shortcut in that mode to start and stop music. This means you have to navigate to the media player to start and stop music — a good example of what we mean by clunky...

Although there are two perfectly good buttons, to pause or end a workout, you can only swipe right and use the touchscreen. We feel there could have been a more efficient way to do this, by using the buttons.

Despite the clunkiness of the interface, we found the strap comfortable to wear, barely even noticing we had a smartwatch on. The white leather strap looked quite stylish, and more like a normal watch when wearing it day to day. Although incredibly comfortable to wear, we did find the watch tended to slide down our wrist, which can mean some statistics may not be as accurate as they could be.

Saying that, we found the statistics to be quite accurate. We measured our BPM independently and checked this against the readings from this watch and they were close enough. The Xiaomi Watch 2 also captured our walking routes well and measured kilometers travelled pretty accurately.

When used in the swimming pool, the watch captured our lengths, time and stroke perfectly. It also gave us our SWOLF score, number of strokes, pace, calories burnt and meters swam. When tested against another fitness watch at the same time, though, we did notice some of the stats varied.

We tested the watch during various workouts such as walking, Zumba, yoga and swimming, with it always managing to capture the data well. We had a few issues with it due to it being so comfortable to wear during our workouts.

One thing we would note is that it's better to have the TPU strap for swimming than the leather one: This remained damp for hours after our swim and was slightly less comfortable. Be aware that when you end your swim, the watch automatically clears the water from itself, but this results in a loud beeping noise if you have the sound on.

We enjoyed using the extra features on the Xiaomi Watch 2, including the sleep monitoring and stress measuring. While the stress measuring was interesting, we found the scores didn't change much: we were apparently always "mildly stressed" even when our bodies were telling us otherwise. We'd advise using this measure with caution.

The sleep monitoring was pretty accurate and lined up with how we felt we'd slept.

We were left disappointed with the range of breathing exercises available on this watch compared to others we've tested. There is only one option, which sees you breathe in and out for anywhere from one minute to five. We found this was a bit dull and other breathing techniques would make this function more useful.

The real disappointment with this watch is the minimal battery life. We could only get the watch to last for a maximum of three days before it needed charging again. This felt cumbersome — a longer battery life would make this watch far more attractive.

Xiaomi Watch 2: Functionality

• Unobtrusive to wear
• Interface could be more intuitive
• Disappointing battery life

Overall, the Xiaomi Watch 2 performed well for a budget fitness tracker. The large screen allowed the colorful graphics to be seen clearly as well as enabling you to view numerous workout stats with ease. Plus, it was comfortable to wear.

Once you've made your way around the watch, the interface feels okay, but we found it unintuitive to use from the get-go and wish it were less clunky to navigate between screens. Our main disappointment with this watch, though, is the poor battery life. It was frustrating to have to keep charging the watch so often and it felt like it couldn't keep its charge. Even on days when the watch wasn't used excessively, the battery would drop significantly.

We liked that the buttons sat flush on the bezel, meaning there was no danger of accidentally pressing them. As there are two buttons, we do feel they could have been put to better use for navigating your way around the watch. There's potential there to make them more useful.

The Xiaomi Watch 2 performed well, measuring our workout and health stats reasonably accurately, so we don't have much to grumble about on this front. The main things that let this watch down were the poor battery life and the clunkiness of the navigation. Other than that, this is a bargain fitness watch that can perform well across different workouts.

Should you buy the Xiaomi Watch 2?

We enjoyed testing the Xiaomi Watch 2 and, for a budget fitness tracker, it performed well across all of our tests. The health and workout stats were reasonably accurate from what we could tell. While we found navigation around the watch a bit frustrating, the positive is that it's uncomplicated once you know how to navigate around it.

The main menu is clear and there are no frills to this watch, so it would be good for those new to smartwatches or to tracking their fitness. Although we were a little disappointed by the lack of customization available, this might actually be a positive to newbies — it leaves little room to get lost and confused in the options and data. Those looking for a more robust, accurate and fancy smartwatch will probably want to look elsewhere.

Saying this, we found the data that was captured and displayed in numbers and graphs on both the watch and app detailed and interesting. You get a lot of information with every workout, so you won't be shortchanged on that front. With the added features such as cycles, sleep monitoring and blood oxygen levels, you can get a good idea of your overall health and this is a bonus.

If this product isn't for you

If you're a keen sports person and the Xiaomi Watch 2 doesn't feel right, the Garmin Instinct 2 may suit you better: We rated it the best for cycling, swimming and running.

Another option is the Amazfit Balance, coming in at a similar price point to the Xiaomi Watch 2. We voted it the best fitness tracker overall. Similar in design to the Xiaomi Watch 2, the Amazfit Balance offers a much longer battery life.

Right now in the Amazon Big Spring Sale there is a massive 41% off the NordicTrack Commercial S22i Studio Cycle. It takes it down to $899.99 and equates to a $610 saving of the $1,499.99 MRSP — so at this price its a brilliant exercise bike deal and terrific value for money.

Buy the NordicTrack Commercial S22i Studio Cycle for just $899.99 at Amazon.

NordicTrack is a big player in the home fitness market and many of it's products hold much coveted spots in many of our best fitness equipment buyers guides — including the best rowing machines and best treadmills. Although we've yet to review this particular model, the NordicTrack Commercial S22i Studio Cycle has some unique features that make it an attractive offering for anyone looking to boost their general health, fitness and cycling performance from the comfort of their own home.

Cycling is one of the best ways to boost your cardio fitness, but you don’t need to leave the house to get started. The NordicTrack Commercial S22i Studio Cycle is a great option to consider when looking at an indoor exercise bike.

This machine has some fairly unique features like an adjustable incline from +20 to -10%, AutoAdjust resistance and incline. It integrates with the iFit app through the large 22-inch touchscreen which provides an immersive experience that simulates real-world riding.

iFit includes an extensive library of studio classes, but the real highlight is the trainer-led real world rides that take you to some of the worlds most scenic cycling locations from Japan to Hawaii. NordicTrack says it delivers alongside the AutoAdjust incline an extremely realistic ride. So realistic that the NordicTrack is the only indoor cycling brand to have an officially licensed Tour de France machine.

Elsewhere, to further enhance the user experience, the bike features an adjustable cooling fan and an immersive sound system for listening to your favorite workout music and clear audio for every iFit workout.

At full price, the NordicTrack Commercial S22i Studio Cycle is excellent value, but with 41% off the usual price, it's a hard-to-beat exercise bike deal.

Key features: AutoAdjust resistance and incline, iFit app with studio and real-world workouts, 22-inch touchscreen, adjustable fan, immersive sound system.

Price history: With a launch MRSP $2,000, the price has slowly dropped and generally held steady at around $1,699 on Amazon. It lowest price to date has been $1,099 — so with this whopping 41% off, the NordicTrack Commercial S22i Studio Cycle is at it's cheapest ever price.

Reviews consensus: The NordicTrack Commercial S22i Studio Cycle is a great choice for anyone new to indoor cycling and looking for a machine that comes with tons of on-demand and instructor-led lead workouts, especially at this price. Amazon reviewers have been overwhelmingly positive on the NordicTrack, and it gets an aggregate score of 4 out of 5 from almost 5,000 ratings, with 63% of reviewers giving it top marks.

Buy it if: You want a fantastic exercise bike with brilliant real-world locations and studio instructor-led classes.

Don't buy it if: You want another type of exercise machine, the NordicTrack x22i is our best in guide treadmill and has a small discount on Amazon.

The researchers discovered the cells in the retina, a light-sensitive structure at the back of the eye that is vital for vision. The cells were found in donated samples of fetal tissue.

The scientists also identified the same cells in lab-grown models of the human retina — and when they tried transplanting those models into mice with a common eye disorder, it restored the rodents' vision.

"This research not only deepens our understanding of retinal biology but also holds immense potential for advancing therapeutic interventions in RD [retinal degeneration] diseases," the researchers wrote in a paper describing the findings, which was published March 26 in the journal Science Translational Medicine.

Related: Scientists restore monkey's vision with a patch made from human stem cells

The retina detects light and converts it into signals that the brain can then interpret to determine what we're seeing. Deterioration of the retina is a leading cause of blindness worldwide. It can be triggered by many things, including aging, diabetes and physical injury, and the degeneration can lead to common eye diseases, such as macular degeneration and retinitis pigmentosa.

Current treatments for these conditions focus mainly on reducing the rate at which retinal cells deteriorate, and protecting those that are still healthy. However, there are currently no effective therapies that promote repair of the retina, which would effectively reverse the deterioration.

A potential solution is to replace deteriorated cells with stem cells — cells that can mature to become any type of cell in the body under the right conditions. Yet, until now, scientists haven't found suitable stem cells in the human retina to achieve this, the authors of the new study wrote.

In the new research, the team analyzed the activity of cells in the fetal retinal samples in the lab. The scientists discovered two types of retinal stem cells with promising regenerative properties: human neural retinal stem-like cells (hNRSCs) and retinal pigment epithelium (RPE) stem-like cells.

The researchers found that both types of cells, which were located in the outer edge of the retina, could clone themselves. However, only hNRSCs could turn into other types of retinal cells under the right conditions.

In a separate experiment, the researchers grew miniature replicas of the human retina in petri dishes. These 3D tissue models, known as organoids, better mimic the unique complexities of human organs than traditional animal models do.

An analysis of the cells within these organoids revealed that they contained hNRSCs similar to those found in the fetal tissue samples. The team also identified specific molecular chains of events that turned the stem cells into other retinal cells and regulated the repair process.

When transplanted into the retina of mice with a disease similar to retinitis pigmentosa, the stem cells from the organoids turned into the retinal cells needed to detect and process light signals. These new retinal cells ultimately improved the vision of the mice, compared with rodents that didn't receive any transplanted cells. This effect was seen for the duration of the experiment, up to 24 weeks.

Taken together, these early findings suggest that hNRSCs could be used to develop new treatments for retinal eye disorders in humans. But more research will be needed to confirm the potential of these cells for restoring the vision of human beings.

In this day and age, Green argues that injustice is the root cause of TB cases and deaths, and that we can collectively choose to correct that injustice and finally snuff out the deadly disease.

Related: 'We have to fight for a better end': Author John Green on how threats to USAID derail the worldwide effort to end tuberculosis

At the time, I knew almost nothing about TB. To me, it was a disease of history — something that killed depressive 19th-century poets, not present-tense humans. But as a friend once told me, "Nothing is so privileged as thinking history belongs to the past."

When we arrived at Lakka, we were immediately greeted by a child who introduced himself as Henry. "That's my son's name," I told him, and he smiled. Most Sierra Leoneans are multilingual, but Henry spoke particularly good English, especially for a kid his age, which made it possible for us to have a conversation that could go beyond my few halting phrases of Krio. I asked him how he was doing, and he said, "I am happy, sir. I am encouraged." He loved that word. Who wouldn't? Encouraged, like courage is something we rouse ourselves and others into.

My son Henry was 9 then, and this Henry looked about the same age — a small boy with spindly legs and a big, goofy smile. He wore shorts and an oversized rugby shirt that reached nearly to his knees. Henry took hold of my T-shirt and began walking me around the hospital. He showed me the lab where a technician was looking through a microscope. Henry looked into the microscope and then asked me to, as the lab tech, a young woman from Freetown, explained that this sample contained tuberculosis even though the patient had been treated for several months with standard therapy. The lab tech began to tell me about this "standard therapy," but Henry was pulling on my shirt again. He walked me through the wards, a complex of poorly ventilated buildings that contained hospital rooms with barred windows, thin mattresses, and no toilets. There was no electricity in the wards, and no consistent running water. To me, the rooms resembled prison cells. Before it was a TB hospital, Lakka was a leprosy isolation facility — and it felt like one.

Inside each room, one or two patients lay on cots, generally on their side or back. A few sat on the edges of their beds, leaning forward. All these men (the women were in a separate ward) were thin. Some were so emaciated that their skin seemed wrapped tightly around bone. As we walked down a hallway between buildings, Henry and I watched a young man drink water from a plastic bottle, and then promptly vomit a mix of bile and blood. I instinctively turned away, but Henry continued to stare at the man.

I figured Henry was someone's kid — a doctor, maybe, or a nurse, or one of the cooking or cleaning staff. Everyone seemed to know him, and everyone stopped their work to say hello and rub his head or squeeze his hand. I was immediately charmed by Henry — he had some of the mannerisms of my son, the same paradoxical mixture of shyness and enthusiastic desire for connection.

Henry eventually brought me back to the group of doctors and nurses who were meeting in a small room near the entrance of the hospital, and then one of the nurses lovingly and laughingly shooed him away.

"Who is that kid?" I asked.

"Henry?" answered a nurse. "The sweetest boy."

"He's one of the patients we're worried about," said a physician who went by Dr. Micheal.

"He's a patient?" I asked.

"Yes."

"He's such a cute little kid," I said. "I hope he's going to be okay."

Dr. Micheal told me that Henry wasn't a little boy. He was seventeen. He was only so small because he'd grown up malnourished, and then the TB had further emaciated his body.

"He seems to be doing okay," I said. "Lots of energy. He walked me all around the hospital."

"This is because the antibiotics are working," Dr. Micheal explained. "But we know they are not working well enough. We are almost certain they will fail, and that is a big problem." He shrugged, tight-lipped.

There was a lot I didn't understand.

After I first met Henry, I asked one of the nurses if he would be okay. "Oh, we love our Henry!" she said. She told me he had already gone through so much in his young life. Thank God, she said, that Henry was so loved by his mother, Isatu, who visited him regularly and brought him extra food whenever she could. Most of the patients at Lakka had no visitors. Many had been abandoned by their families; a tuberculosis case in the family was a tremendous mark of shame. But Henry had Isatu.

I realized none of this was an answer to whether he would be okay.

He is such a happy child, she told me. He cheers everyone up. When he'd been able to go to school, the other kids called him pastor, because he was always offering them prayers and assistance.

Still, this was not an answer.

"We will fight for him," she told me at last.

Editor's note: This excerpt, from Chapter 1 of "Everything is Tuberculosis," has been shortened for the purpose of this reprinting.

Affected populations: TMAU is a rare metabolic condition that causes a person to smell like rotten fish. The condition is more common in women than in men, and there's evidence that female sex hormones, such as progesterone, can exacerbate patients' symptoms.

The exact prevalence of TMAU is unknown, and estimates of global cases vary greatly, ranging from 1 in a million to 1 in 200,000 people.

Causes: Patients with TMAU smell like fish due to a buildup of a chemical called trimethylamine in their body. Trimethylamine is produced by bacteria in the gut as a byproduct of the digestion of certain foods, including eggs, liver, legumes and specific kinds of seafood, such as fish, squid and crabs.

Related: Why can't we smell ourselves as well as we smell others?

Normally, an enzyme in the body breaks down trimethylamine into an odorless chemical, known as trimethylamine N-oxide, which is then excreted via urine. This enzyme is encoded by a gene called FMO3.

In patients with TMAU, though, this enzymatic process doesn't occur, so trimethylamine accumulates in the body and ends up being released in excess quantities in patients' sweat, urine and breath. This makes them smell like rotten fish.

Most cases of TMAU are caused by mutations in the FMO3 gene that prevent the enzyme it encodes from working properly. In these instances, patients inherit the disease in an autosomal recessive manner, meaning they must inherit two copies of the mutated FMO3 gene — one from each parent — to develop the condition.

More rarely, TMAU can be caused by consuming a large quantity of foods that lead to trimethylamine production. It can also result from liver failure and certain medical treatments, such as testosterone replacement therapy, which impact the processing and production of trimethylamine, respectively. Hormonal changes brought about by the menstrual cycle can also cause a transient form of TMAU.

Symptoms: Symptoms of TMAU may be present from birth or arise later in life, normally near the start of puberty (roughly around age 8 to 13 in females and 9 to 14 in males), when many hormonal changes happen.

Some patients with TMAU have a strong fishy odor all the time, while the smell may come and go for others with the condition. A patient's stress levels and diet can worsen their symptoms by increasing their sweat production and levels of trimethylamine, respectively.

TMAU is not deadly, but the condition can have devastating effects on patients' quality of life, by impeding their relationships with others and their career, for instance. These impacts can considerably impede their mental health and may lead to symptoms of depression, anxiety and suicidal thoughts in some.

Treatments: There is no cure for TMAU. However, health care providers may recommend that patients avoid foods that contain trimethylamine or substances that can be broken down into the chemical. These include milk from wheat-fed cows, as well as eggs, liver, kidney, seafood and peas.

Patients may also be advised to wash their skin with a slightly acidic soap or shampoo, to avoid strenuous exercise that causes sweating, to wash their clothes frequently and to use antiperspirant. They may also be advised to take measures to reduce their stress levels.

Additionally, doctors can prescribe low doses of antibiotics to reduce the amount of bacteria in the gut that metabolize trimethylamine. They may also prescribe activated charcoal, which binds to and reduces the amount of trimethylamine that can be absorbed from the gut. (Activated charcoal can interact with many medications, though, so it should be used with caution.)

This surge in infections in low- and middle-income countries would contribute up to 2.9 million more HIV-related deaths by 2030.

These disturbing figures come from a new modeling study published March 26 in the journal The Lancet HIV. The researchers wanted to analyze the potential impact of cuts to international funding for HIV/AIDS programs, which work to prevent both transmission and deaths related to the infection.

As of February 2025, the five top donors of this funding — the United States, United Kingdom, France, Germany and the Netherlands — have all announced significant cuts to foreign aid that threaten HIV programs worldwide. The study predicts how these cuts would impact low- and middle-income countries (LMICs), which since 2015 have relied on international sources for 40% of their HIV program funding.

"These findings are a sobering reminder that progress in the fight against HIV is not guaranteed — it is the result of sustained political will and investment," said Dr. Ali Zumla, a professor of infectious diseases and international health at University College London who was not involved in the research.

But equally, "the projected surge in new infections and deaths is not an inevitability; it is a consequence of choices being made today," Zumla told Live Science in an email. "If these funding cuts move forward, we risk unraveling decades of hard-won progress, leaving millions vulnerable and pushing global HIV goals further out of reach."

Related: We could end the AIDS epidemic in less than a decade. Here's how.

Unprecedented cuts to aid

As of 2023, five donors have supplied more than 90% of the international funding for HIV programs, with the United States providing over 72% of the total. Specific populations at high risk of HIV — including people who inject drugs, men who have sex with men, female sex workers and their clients, and transgender and gender diverse people — particularly rely on these international funding sources for access to HIV prevention and testing.

Much of the U.S. funding comes from the President's Emergency Plan for AIDS Relief (PEPFAR), which is largely implemented by the Agency for International Development (USAID). However, PEPFAR and USAID were hit by an unprecedented funding pause and staffing reduction in January, following an executive order from President Donald Trump.

PEPFAR later received a temporary waiver to continue some services, including those for antiretroviral therapy (ART), the drugs that keep HIV from progressing to AIDS. These treatments must be taken consistently or the virus will rebound.

"The widespread rollout and uptake of antiretroviral therapy funded by international sources has been one of the most important factors reducing AIDS related deaths in lower income settings," said Justin Parkhurst, an associate professor of global health policy at the London School of Economics and Political Science who was not involved in the study. ART also cuts the number of new infections by suppressing the virus in people living with HIV, thus preventing transmission, he told Live Science in an email.

However, despite the waiver, PEPFAR's services still haven't resumed as normal, given the waiver didn't trigger immediate funding to eligible programs and many clinics had already shuttered by the time it was issued. Even now, PEPFAR's future after the waiver's expiration remains uncertain.

Following the U.S., the next top four donors for international HIV funding are the U.K., France, Germany and the Netherlands. However, as of February 2025, each of these donors has also announced major cuts in foreign aid spending — "and more might follow," the study authors wrote.

Based on the projected cuts being made by the top five donors, the researchers used a mathematical model to predict the rates of new HIV cases and deaths. They focused their model on 26 LMICs, which together receive 49% of international HIV aid, overall, and 54% of PEPFAR aid. They then used the data from these 26 countries to extrapolate to all LMICs worldwide.

Cuts could "undo nearly all progress achieved since 2000"

The researchers considered several scenarios in their model. The first — the "status quo" — served as a baseline, projecting the rates of cases and deaths if recent levels of HIV spending were maintained between 2025 and 2030, rather than cut. In this scenario, more than 1.8 million new infections and over 720,000 HIV-related deaths occurred in LMICs.

In the worst-case scenario the team considered, all PEPFAR funding was indefinitely stopped on Jan. 20, 2025, and no alternative funding sources emerged to fill that gap. Simultaneously, other, non-PEPFAR sources of international funding were also reduced. That scenario led to an estimated 10.8 million more cases and 2.9 million more deaths than the status quo.

Related: Single-shot HIV treatment suppresses virus 10,000-fold for months, animal study finds

This suggests that "the number of new infections in 2026 could return to 2010 levels, and by 2030 the number of new infections could surpass historical estimates," the study authors wrote. "In the worst-case scenario, if PEPFAR funding were ceased entirely and no equivalent mechanism replaced it, surges in HIV incidence could potentially undo nearly all progress achieved since 2000."

This worst-case scenario would hit sub-Saharan Africa (SSA) particularly hard — out of eight SSA countries included in the analysis, six receive over 40% of their HIV funding through PEPFAR. Children in the region could see a nearly three-fold increase in HIV infections, the authors predicted.

And outside of SSA, other vulnerable populations, such as sex workers, would be much harder hit by such cuts than the general population, showing up to a six-fold higher increase in cases than other demographics, the data suggested.

The team also looked at a less extreme scenario, modeling what would happen if new funding sources filled the gap left by PEPFAR. In this scenario, they assumed that the gap could be partially filled by 2026 and then fully filled by 2027. If that mitigation were to happen, the number of extra cases drops to 4.4 million and the extra deaths to 770,000 over the course of five years.

So while filling the gap left by PEPFAR would help substantially, that sudden loss of funding would still have devastating impacts, the study suggests.

"Modelling reveals the potential for severe consequences following abrupt stopping, with no notice, of international support aimed at stopping AIDS as a global public health threat," Dr. Catherine Hankins, a professor of global and public health at McGill University in Canada who was not involved in the study, told Live Science in an email.

Cuts could be felt for decades to come

According to the study authors, even if the PEPFAR gap could be filled within two years, the ripple effects would be felt for decades to come. They estimated that it would take 20 to 30 extra years of 2024-level funding to end AIDS as a public health threat.

Ambitious goals set by UNAIDS have aimed to end the threat by 2030. And historic HIV trends suggested that many of the LMICs featured in the new paper could have hit their targets by about 2036, if funding continued at past levels, the authors wrote.

"This study indicates that an abrupt termination of programmes has serious risks to human life," Parkhurst said. "Even for those who believe the US or other governments should reduce foreign aid spending in this area, there can be planning around how to do so without producing serious harm to millions of people around the world who have come to rely on the treatment."

The study suggests that, if that abrupt stop could be avoided, many lives could be spared.

The researchers looked at what would happen if PEPFAR was reinstated or "equivalently recovered" and estimated that there could be 70,000 to 1.73 million extra cases and 5,000 to 61,000 extra deaths, compared to status quo. Those estimates assume that other international funding will still be reduced, but that countries will be able to make up for some of the lost funds domestically.

The new study has some limitations, as "there is inherent uncertainty in global modelling," said study co-first author Rowan Martin-Hughes, a senior research officer at the Burnet Institute in Australia.

The "most important" limitation is that there is uncertainty in the HIV fiscal space, although the authors covered some of that unpredictability by looking at a range of possible outcomes, Martin-Hughes told Live Science in an email. There are also gaps in the global reporting of financial data that could affect their model, and the 26 featured countries might not be fully representative of the overall impacts of funding cuts, he added.

However, "overall, we think most sources of uncertainty are likely to result in underestimating rather than overestimating the real effects of immediate and severe funding cuts to HIV programmes globally, especially in the sub-Saharan African region," he said.

In light of the impending cuts, "it is paramount now to track AIDS mortality and HIV incidence while urgently reversing the cuts, mitigating the effects, and creating new funding strategies to prevent further suffering," Hankins said.

Martin-Hughes agreed.

"Governments, donors, and stakeholders must collaborate on feasible mitigation strategies to preserve HIV prevention, testing, and treatment services to avoid a resurgence in the HIV epidemic," he said. "In doing so, the global community can secure both the immediate and long-term stability of resilient health systems so integral to saving lives through HIV epidemic control."

Global investment, especially from the U.S., has put targets for the elimination of HIV transmission within reach, he said. "But all of that progress is vulnerable, and could be wiped out within a few years if there are dramatic and unmanaged cuts to HIV services."

Editor's note: This story was updated on March 27, 2025, to include new quotes from an author of the study, Rowan Martin-Hughes. The article was first published March 26.

The research, published March 3 in the journal PNAS, seems to align with the results of a different study that Live Science recently reported on, which looked at aging using blood samples and found that periods of accelerated aging take place around ages 44 and 60.

The new neuroscience study also found that brain aging was linked to insulin resistance, in which cells need more insulin than usual to keep blood sugar in check. Furthermore, it uncovered early hints that ketone supplements may offer some protection against certain measures of brain aging.

Ketones are compounds in the body that act as an alternative fuel source, standing in for sugars. So if the brain is aging because it's not getting enough sugars, ketones could help fill the gap, the team theorized.

However, much more research is needed to back this idea.

Related: 13 proteins tied to brain aging seem to spike at ages 57, 70 and 78

Early warning signs of brain aging

The researchers used four existing datasets of brain scans that together included scans from 19,300 people ages 18 to 90. To study how different brain regions are linked in networks, the team looked at two types of brain scans: functional magnetic resonance imaging (fMRI), which measures blood flow in the brain, and electroencephalograms (EEGs), which measure electrical firing between neurons in the outermost layer of the brain.

In these scans, the scientists looked for signs that blood flow and electric firing between brain regions either disappeared or became inconsistent, suggesting there was a breakdown in communication between nodes in the network. They had considered this network disintegration a hallmark of aging in previous research wherein they assessed the impact of diet on the brain. Such disruptions are also seen in age-related neurodegenerative diseases, and the degree of disruption typically reflects the person's overall degree of aging.

Through their analysis, the researchers found that the brain starts to age more quickly around age 44 and that the aging accelerates to a maximum rate around age 67. After that, brain aging starts slowing down, until the rate stabilizes around age 90.

"What we did not anticipate was that the effects might be occurring as early as the 40s," study senior author Lilianne Mujica-Parodi, a neuroscientist at Stony Brook University, told Live Science.

Sugars versus ketones

The network disruptions the researchers observed resembled changes previously documented in the brains of people ages 50 to 80 with type 2 diabetes. Mujica-Parodi and her team wondered if the changes arose because neurons were not responding well to insulin, the hormone responsible for shuttling sugar from the blood into cells.

This effect wouldn't affect only people with diabetes. About "88% of North Americans have at least one detectable sign of insulin resistance," said Dr. Luis Adrian Soto-Mota, a metabolism researcher at the Monterrey Institute of Technology in Mexico who was not involved with the study but previously worked with the team.

Looking at all the brain scans, which included scans from people with and without insulin resistance, the team found that people in their 40s with high blood sugar levels experienced faster brain aging than people of the same age with no signs of insulin resistance.

In addition, across all of the scans, certain parts of the brain aged more quickly than others, so the researchers wondered if those brain regions might be more insulin dependent. It's known that a protein named GLUT4 relies on insulin to move sugar into cells. So the team turned to the Allen Brain Atlas, which includes data on the activity of the GLUT4 gene, and found that the fast-aging regions did depend more on GLUT4.

The slow-aging brain regions, on the other hand, had higher levels of a protein that moves ketones into cells, suggesting that those regions use ketones as an alternative energy source.

Related: Biological aging may not be driven by what we thought

Ketone supplements?

That raised the question of whether ketone supplements might be able to slow brain aging. To test this idea, the team recruited 53 men and 48 women, ages 20 to 79, who got fMRI scans after fasting overnight to deprive the brain of sugar.

Half an hour after the scan, the participants received either a ketone-filled drink or a sugary drink with the same number of calories. The researchers then waited 30 minutes for the energy source to reach the participants' brains, before repeating the fMRI scans.

Even over this short time frame, the ketone drink appeared to reduce brain network disruptions tied to aging, while the glucose beverage didn't, the team found.

The ketone drink had the greatest effect on people ages 40 to 59, where its impact was over 80% higher than in younger adults ages 20 to 39. The ketone drink had the smallest effect in the 60-to-79 age group. That might hint that, if ketone supplements prove to be effective for slowing brain aging, early intervention could be necessary.

This part of the study was limited in that the researchers tested the effects of ketone and glucose drinks only at a single time point; they didn't monitor brain aging over time or conduct any cognitive tests. They also considered only specific fMRI data, which may not reflect all aspects of brain aging, so we don't know if ketone supplements would help across the board.

Mujica-Parodi said future studies could track brain aging in people taking these supplements over time and thus provide more insight into its long-term potential. In addition, if the ketone supplements are making up for insulin resistance, the best measure people could take might be to avoid developing insulin resistance in the first place, she suggested, which could be achieved through dietary changes.

Soto-Mota added that when glucose levels are low enough, the body can make more ketones on its own than it can obtain from supplements. That's the goal of the "keto diet," although maintaining the diet for a long time comes with downsides.

Mujica-Parodi said that ketone supplements could be helpful in people with extreme insulin resistance who are incapable of making their own ketones, due to metabolic changes in the body.

Editor's note: Some of the authors on the new paper have patented the ketone supplement tested in the research, and one is the director of a company aimed at developing products based on the science of ketone bodies in human nutrition.

Brain quiz: Test your knowledge of the most complex organ in the body

Through these operations, the brain directs our unconscious bodily functions, such as our appetites and levels of wakefulness, as well as "higher order" cognitive abilities — solving problems, generating ideas, planning for the future. The brain has inherent plasticity, meaning it dynamically responds to novel information and literally restructures itself to accommodate new memories and new interpretations of the world around us.

Scientists are still unraveling the brain's inner workings, but over the decades, they've learned quite a lot about what makes the organ tick. Check out the quiz below to test your knowledge of the human brain and its many unique features.

Remember to log in to put your name on the leaderboard; hints are available if you click the yellow button, and let us know your score in the comments.

More science quizzes

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The symptoms: The patient went to the hospital after experiencing 10 days of gut pain and fever. Doctors performed an ultrasound of the man's abdomen and found an abscess — a pus-filled mass — in the right lobe of his liver. They drained the abscess and gave the patient a 10-day course of antibiotics. His fever subsided, and the man was sent home.

However, a month later, the man ended up in the emergency room after experiencing six consecutive days of abdominal pain and a fever above 102.4 degrees Fahrenheit (39.1 degrees Celsius) — an apparent relapse of symptoms.

What happened next: During the man's second hospital visit, blood tests showed that he had an elevated count of white blood cells, a type of immune cell that fights infections, and lower-than-average levels of albumin, a protein produced in the liver. Doctors conducted an abdominal X-ray but detected no abnormalities. A computed tomography (CT) scan of the patient's abdomen showed that his kidneys, spleen, pancreas and gallbladder looked normal, the doctors wrote in a report of the case.

However, when the medical team examined the central region of the patient's liver, they found two anomalies. One was a lesion that looked like an abscess, and the other was a solid, twig-like object inside that lesion measuring about 1 inch (2.5 centimeters) long.

The diagnosis: The doctors suspected that the unidentified object had caused the abscess and that it likely resulted in the patient's first abscess a month prior, as well.

The treatment: After giving the patient antibiotics, the doctors performed a type of abdominal surgery called a laparotomy to remove the foreign object. It turned out to be a fish bone.

The patient said he had probably swallowed it while eating fish during a meal about five months earlier, but he did not recall feeling anything unusual at the time. Post-surgery, the man's condition improved. Over the next three months, the hospital monitored his health through follow-up visits, and he had no further abdominal issues.

What makes the case unique: Liver abscesses are rare. In North America, about two cases are reported per 100,000 people each year, and estimates for other locations can reach about 17 per 100,000 people annually. The most common causes of these pus-filled lesions are infections that originate in the blood, bile ducts or abdominal organs.

Notably, the patient had a healed scar in a section of the small intestine called the duodenal bulb. This suggested that the swallowed fish bone had probably pierced the man's intestinal wall and then migrated from there into his liver.

Most small fish bones, if swallowed, pass harmlessly through the gut within about a week, according to the case report.

This phenomenon may help to explain why, on many measures, females show a higher level of cognitive resilience in old age than males do.

The findings come from a new study in lab mice, and the researchers also backed up the results with genetic data from humans. More research is still needed to confirm that the findings in mice translate to people, but overall, the work points to a potential difference in how female and male brains age.

Historically, "we simply haven't looked at the X chrom[osome] very much," said Rachel Buckley, an associate professor of neurology at Harvard Medical School who was not involved in the new study. "And now we're starting to really shine a very, very big spotlight on it, and we're starting to realize things that we had not fully appreciated" — namely, how sex chromosomes might influence how the brain ages.

"There are very important and potentially therapeutic targets that are coming out from these papers" that focus on the X chromosome, Buckley told Live Science.

Related: Is there really a difference between male and female brains? Emerging science is revealing the answer.

The resilience of the female brain

There seem to be fundamental differences in how males and females age. When it comes to the brain, females have lower rates of various forms of dementia than males do, even though females live longer, on average. One exception is that females have higher rates of Alzheimer's disease than males do, although females with Alzheimer's tend to survive longer than males with the condition.

"There's been a lot of documented trends where there's resilience in cognitive aging in female populations, compared to males," said study first author Margaret Gadek, an MD-PhD student at the University of California, San Francisco. "There's a lot of reasons why these trends could be in place, but one thing we wanted to look into was the role of the X chromosome," Gadek told Live Science.

Alongside hormones, the sex chromosomes — X and Y — are one of the starkest biological differences between males and females, and they could help provide biological explanations for why these differences emerge in aging.

Males typically carry one X and one Y in each cell; they inherit the X from their mother and the Y from their father. Females, on the other hand, usually carry two X chromosomes — one from mom and one from dad. But each cell needs only one X to be active, so in females, the second X is "silenced," leaving only the maternal or paternal X switched on.

This is not a seamless process. Some genes on the silenced X chromosome escape that silencing process, and thus remain switched on, while additional genes may get switched back on as a person ages. Gadek and her colleagues wondered how these "reawakened" genes might factor into brain aging, especially given that this silencing is a uniquely female phenomenon.

Related: 'Let's just study males and keep it simple': How excluding female animals from research held neuroscience back, and could do so again

Nearly two dozen "reawakened" genes

In their new study, published March 5 in the journal Science Advances, the researchers crossed two subspecies of lab mice — called Mus musculus and Mus castaneus — so that each of the rodents' offspring would inherit one X from the former subspecies and one from the latter. The team also genetically tweaked the mice such that the X from M. castaneus was always silenced. Normally, the X that happens to be silenced in each cell is random.

This experimental setup made it easier to tell which chromosome an active gene belonged to and, therefore, whether it had "escaped" the silencing process, Gadek explained.

With their modified mice in hand, the team then examined the gene activity in four young mice and four old mice, the latter of which were 20 months old. (That's about 65 in human years.)

They specifically zoomed in on gene activity in cells of the hippocampus, a key memory center in the brain that tends to shrink with normal aging and cognitive decline and is heavily impacted in dementia. They looked at over 40,000 cells in total, including both neurons and various types of glial cells, which help maintain and support neurons in the brain and also make an insulating substance, called myelin.

This analysis revealed that, with age, about 22 genes that were initially silenced got switched back on. Some of the same genes were reawakened across many the mice, while others were more variable, Gadek added.

"I was really shocked to see that we could be thinking about X-related inactivation escapism as a function of age," Buckley said. "So as women get older, there'll be more of it" — meaning X-linked gene activity — "and in fact some of it's quite protective," she added.

Importance of insulation in the brain

Among the 22 reawakened genes, one called PLP1 jumped out as interesting, in part because it was switched on in seven of the nine cell types studied, Gadek said.

PLP1 carries the instructions to make a key component of myelin, the fatty insulation that helps neurons send signals efficiently. It's known that mutations in PLP1 can decrease the amount of myelin in the brain, resulting in intellectual disability. It's also known that myelin can be compromised in aging and that loss of myelin function can contribute to cognitive decline.

To see if the reawakening of PLP1 might boost cognition, the scientists ran some experiments with male and female mice. In one, they confirmed that older female mice had more PLP1 activity in their hippocampi than the older male mice did. In the second experiment, the researchers artificially increased PLP1 using gene editing in both old males and old females, and they found that both sexes performed better on tests of learning and memory after that boost.

To see if any of the findings extended to humans, the team looked at data previously collected for a large study of human brain tissue. Data weren't available for the hippocampus, but the brain tissue immediately surrounding the hippocampus showed more PLP1 activation in older women than in older men. So that hints that the same phenomenon might be unfolding in people.

Gadek said that, in the future, she'd be interested in looking at this reawakened gene in animal models of diseases like dementia, since the current mouse experiments looked at only healthy aging. Buckley added that it would also be interesting to investigate the phenomenon in the context of menopause.

Related: Faster brain aging tied to X chromosome inherited from Mom

In menopause, estrogen levels plummet. The hormone has many functions in the brain, including helping shuttle fuel from the blood into brain cells. Buckley pointed to research led by neuroscientist Roberta Brinton of the University of Arizona, which suggests that, as estrogen levels decline, the brain may break down some of its own myelin for fuel.

In reading the new study, Buckley connected the dots and wondered if the boost in myelin in later life could be a way of recovering from the hit taken earlier, during menopause. "That's something that really made me sit up and take notice," she said, although this idea is speculative for now.

Given the current study was primarily in mice, Buckley did note that more work is needed to see how this phenomenon unfolds in the human brain. And in the long term, it would behoove scientists to study the role of the Y chromosome in brain aging; although it carries far fewer genes than the X, it may still have an impact, she noted.

"One thing that this paper highlights is that studying sex chromosomes isn't a niche woman's health issue," Gadek said. "It provides insights into cognitive aging and certainly other areas of health that could benefit males and females and everyone alike, because we all have an X chromosome."

In general, taking too much vitamin D can be dangerous; however, the high doses in the new trial were taken in controlled conditions, under the supervision of medical staff, and by patients for whom it was deemed safe.

Multiple sclerosis (MS) is a chronic autoimmune disease that affects the brain and spinal cord. In those with the disease, immune cells mistakenly attack the protective layer around nerve fibers, causing lesions, or scar tissue, to form. This leads to symptoms such as muscle weakness, changes in vision, numbness and memory problems, which may either come and go or get worse over time.

There is no cure for MS. Existing drugs can help patients manage their symptoms, but these medications often have nasty side effects, such as an increased risk of infections and gastrointestinal issues.

Related: Twin study reveals signs of MS that might be detectable before symptoms

Studies suggest that vitamin D deficiency is a potential risk factor for MS. That's because vitamin D can reduce inflammation in the central nervous system in numerous ways — for instance, by inhibiting the release of chemical messengers from immune cells that trigger inflammatory responses. Thus, the theory is that having too little vitamin D may allow runaway inflammation to ensue.

The link between low vitamin D and multiple sclerosis was first identified in the 1960s. Yet, over the years, various clinical trials have tried and failed to show that taking high doses of vitamin D can help to reduce a patients' symptoms or disease progression.

Previous trials may have failed because they included too few participants and monitored patients for only short periods of time, such as a year, said Dr. Eric Thouvenot, co-lead of the new clinical trial and a neurologist at the University of Montpellier in France. Past trials also tested vitamin D supplementation in patients who were already taking drugs to manage their MS, he told Live Science. This made it harder to determine how effective vitamin D was, in and of itself.

To overcome these hurdles, Thouvenot and colleagues took a different approach in their new trial.

They looked at the effects of high-dose vitamin D supplementation in 303 patients with clinically isolated syndrome (CIS). CIS describes when patients have early signs that are suggestive of multiple sclerosis but they have not yet developed the full-fledged disease and don't meet the diagnostic criteria. Signs of CIS include inflammation and damage to the protective layer around nerve fibers.

Although not a given that CIS will progress into multiple sclerosis, this is the case for approximately 85% of MS patients.

The patients in the trial had yet to start taking other drugs for multiple sclerosis, so the researchers had a window in which they could directly investigate the impact of vitamin D supplementation on their disease progression.

During the trial, the team randomly assigned 156 of the patients to take a high-dose of a form of vitamin D called cholecalciferol. They took the supplement once every two weeks for two years, or until they showed signs of MS symptoms or new or growing lesions during medical visits. These visits occurred three months after starting supplementation, one year out and then two years out, and they involved brain and spinal cord scans and MS symptom assessments.

If disease activity was detected, patients would be removed from the trial and immediately prescribed disease-modifying drugs, meaning drugs that alleviate symptoms by targeting the root causes of MS.

A comparison group of 147 patients underwent the same protocol but took a dummy drug instead of vitamin D, according to a report of the trial published March 10 in the journal JAMA.

The dose the vitamin D group received was 100,000 international units, which is around 20 times more than what common drug store supplements contain per dose.

Overall, the researchers found that disease activity occurred in 60% of the vitamin D group within the two-year study window, compared with 74% in the placebo group. The time it took for symptoms to emerge was also significantly longer in the former group than the latter — about 432 days, compared with 224 days.

Taken together, these findings suggest that early supplementation with high-dose vitamin D may help slow the progression of CIS to multiple sclerosis.

This is "important research" and supports the use of high-dose vitamin D by patients with multiple sclerosis, said Dr. Klaus Schmierer, a professor of neurology at Queen Mary University of London who was not involved in the new trial. Many doctors already recommend such supplementation, Schmierer told Live Science in an email.

Many clinicians recommend that MS patients take between 4,000 and 5,000 international units of vitamin D each day. Any more than this can cause a condition called hypercalcemia, in which too much calcium builds up in the body, because vitamin D normally regulates the levels of this mineral in tissues. Hypercalcemia can weaken bones and potentially lead to kidney and heart damage.

Despite being over the recommended limit for vitamin D supplementation, no one in the new trial who received vitamin D developed hypercalcemia. That hinted that this high dose may be safe in this context, and notably, the participants took the supplement twice a month, rather than daily.

However, ultimately, more trials are needed to corroborate these findings.

Furthermore, the aim of this research would not be to replace current disease-modifying drugs for MS but rather to provide another therapeutic option for patients who otherwise don't have access to the drugs, for example because of financial reasons, Thouvenot emphasized.

The test suggested Gormly had colon cancer, which a colonoscopy later confirmed was Stage 2, meaning the cancer had spread through the wall of the colon but not to his lymph nodes.

"I thought [my doctor] was wrong," Gormly, CEO of a construction company near Newport Beach, California, told Live Science. "I go, 'Nah, I don't feel anything.' But there it was. It was real; the colonoscopy showed it."

Gormly was one of the first patients to take a newly approved test called Shield, which its makers say can detect colon cancer from a blood sample. After his diagnosis, Gormly had surgery to remove the tumor and was back to work within 10 days.

An early version of Guardant Health's Shield test has been commercially available since 2022, but it wasn't covered by insurance. However, after approval from the U.S. Food and Drug Administration (FDA) in July 2024, a diagnostic version of Shield was launched commercially and is now covered by Medicare.

Shield is only a blood drop in an ocean of emerging "liquid biopsies."

Scientists have developed blood tests for several cancers, including those of the breast, pancreas and stomach. Some blood tests even detect multiple types of cancer. If these liquid biopsies can be rolled out widely, they could help detect cancer earlier, more easily, or with fewer invasive measures — which, in turn, could lead to earlier detection and fewer cancer deaths.

But many of these tests are still in their early stages. They often detect a lower fraction of cancer cases than gold-standard screening tools like colonoscopies do, meaning they will likely supplement, rather than replace, traditional screening methods. Others may have unacceptable rates of "false positives," meaning a person is initially told they have cancer but diagnostic follow-ups show they do not. This can lead to needless worry or additional invasive tests. These include traditional biopsies, which involve removing tissue samples via needles or surgery. And for some diseases, it's not clear that early diagnosis on a blood test will lead to better outcomes.

However, as these kinks are ironed out, it's likely that blood-based cancer screening will become a normal part of our medical care — one that has the potential to improve cancer outcomes dramatically, experts say.

Simplifying screening

Gormly's doctor recommended a Shield test after noticing that Gormly hadn't had a colonoscopy in a while. He's not alone. Current recommendations suggest that people ages 45 to 75 who are at average risk of colon cancer get a screening, such as a colonoscopy or a stool-based test, every five to 10 years. Yet around 1 in 3 of these people have never been screened.

That's a problem, because colon cancer is the fourth-most-common cancer. Experts have argued that early detection could eliminate 90% of colon cancer deaths. It typically takes around 10 years for early, precancerous growths like polyps to morph into deadly cancer cells, and if these cells are caught early, they can easily be removed.

Despite the potential for early diagnosis and cure, many people avoid these screenings. This may be one reason colon cancer is the second-most-common cause of cancer death.

People avoid screenings for many reasons, said Dr. William Grady, a professor of translational science and therapeutics at the Fred Hutchinson Cancer Center in Seattle who helped lead the Shield trials. Some people feel embarrassed during screenings such as colonoscopy or fear that it may be painful, he told Live Science. Those opting for colonoscopy may struggle to get time off work, whereas others may dislike the idea of handling stool for a stool-based test, he said.

"That's why there's an opportunity for blood tests that is really powerful because people are inclined to do blood tests; they're convenient and can be done during a health care encounter," Grady said.

Shield works by detecting small DNA fragments that are released into the blood from colon cancer cells or precancerous cells called adenomas, a type of polyp. The test also picks up on subtle differences between cancerous cells and normal cells in chemical tags on DNA known as methyl groups.

In a paper published in March 2024 in The New England Journal of Medicine, Grady's team showed that Shield detected 83% of colonoscopy-confirmed colon cancer cases in a cohort of almost 10,000 people. It also had a false positive rate of 10%.

Because Shield detects a smaller percentage of colon cancer cases than stool-based tests (92%) or colonoscopies (95%) do, it won't replace those diagnostic tests, Grady said. However, it could expand the number of screening options available to patients, he added. This additional option may improve screening compliance, which could lead to earlier disease detection and thus a reduction in colon cancer deaths.

The Shield test is approved for use every three years, Grady said. However, current studies are investigating whether it would be more accurate if it were done every year or two, he added.

If Gormly's cancer had spread to the rest of his body, it would have been much harder to treat. People whose colon cancer is caught at Stage 2, like Gormly, have an 85% chance of living at least another five years. By Stage 4, when it has spread throughout the body, those odds go down to just 10%.

"That could have been the end of me, so it [Shield] definitely changed my life," Gormly said.

Accelerating diagnosis

Pancreatic cancer is another disease that could benefit from a blood-based diagnostic test. Unlike colon cancer, pancreatic cancer is relatively uncommon, affecting 1 in 56 men and 1 in 60 women. Yet pancreatic cancer is the third-most-common cause of cancer death in the U.S.

That's because, by the time most people notice symptoms, such as abdominal pain or discomfort, the disease is already very advanced, said Ajay Goel, a professor and chair of the Department of Molecular Diagnostics and Experimental Therapeutics at the Beckman Research Institute of City of Hope in Duarte, California.

There is no broad-based screening program in the U.S. for people at average risk of pancreatic cancer. Later stages of the disease are easily detectable via MRI or CT scan, Goel told Live Science. But by that point, the five-year survival rate is extremely low: around 3% once the cancer has spread throughout the body, compared with 44% if it is still limited to the pancreas. Once cancer has spread beyond the pancreas, surgical removal is usually no longer possible, and treatments such as chemotherapy and radiotherapy are minimally effective.

A potential solution is a new blood test developed by Goel's team. It aims to detect early-stage pancreatic cancer by identifying small cancer-specific molecules called microRNAs. These molecules regulate whether genes are switched on or off and are found in the blood of patients with early-stage disease, as well as inside exosomes, which are tiny packages that cancer cells release into the blood.

In a study of nearly 1,000 people, the test (which is still unnamed) detected between 88% and 93% of early- and late-stage pancreatic cancer cases, using blood drawn from people in the U.S., South Korea and China. When the test was modified to also measure the amount of a protein known as CA-19 in the blood, it picked up 97% of early-stage cases in the U.S. group. CA-19 is a known biomarker of pancreatic cancer, but on its own, it is not reliable enough to be used for diagnosis. When combined with CA-19 detection, the new test had a 5% to 10% false positive rate, Goel said.

The findings, which haven't been peer-reviewed yet, were presented at the 2024 American Association for Cancer Research Annual Meeting in San Diego.

"If you can find more and more of these cancers early on, there is a hope that many of these patients can be cured," Goel said.

The team envisages the test being taken yearly — for instance, when patients see their doctor for an annual physical exam. However, in those who have a family history of pancreatic cancer, it may make sense to test more frequently — perhaps every six months, Goel said.

Multicancer detection

Scientists are also developing multicancer detection (MCD) tests that screen for many types of cancer at once. MCD tests differ slightly in the types of cancer they detect and how they do it. But like many of the single-cancer detection tests, MCD tests look for cancer-specific molecules, such as tumor DNA, but on a larger scale. Some MCD tests sample urine or another bodily fluid in addition to blood.

In theory, such tests could not only provide a less-invasive approach to screening but also reduce the number of tests a person has to take at once. However, most of these tests are still in early development. The ones that are farther along, such as Grail's Galleri and Exact Sciences' Cancerguard, have not received FDA approval yet. And some experts have argued that the tests' efficacy claims are overhyped.

Even if MCD tests do work and they become more affordable (Galleri, for example, currently costs around $950), experts still aren't sure of the best way to use them. "There's this belief that if we could only detect all cancers early, we would solve the cancer problem," Ruth Etzioni, a professor at Fred Hutchinson who was not involved in Grady's work with Shield, told Live Science. But sometimes there is no good treatment for early cancers, so catching them ahead doesn't necessarily lead to improved outcomes.

And there's always a risk of false positives. After taking an MCD test, patients may wait up to six months to know one way or the other, Dr. Jennifer Croswell, a medical officer at the National Cancer Institute, told Live Science. There may be many reasons for this delay, including that it takes time to perform multiple rounds of follow-up testing to figure out which organ is affected, she said. There are also currently no evidence-based clinical guidelines that tell doctors the best way to follow up on positive results from MCD tests, Croswell said. Consequently, these tests may create uncertainty for patients.

The way forward

While many diagnostic blood tests for cancer are still in the pipeline, at least some of these tests will likely affect diagnosis and treatment in the next several years. For instance, Goel and colleagues are now running a clinical trial to see if their test can detect early-stage pancreatic cancer in high-risk individuals who have not yet been diagnosed. If it's successful, they intend to test it in the general population.

"I think if things go well, we foresee that probably in the next two to four years, this test should be on the marketplace to be used for early detection of pancreatic cancer worldwide," Goel said.

Meanwhile, Grady's team is planning to investigate whether Shield helps get more people screened for colon cancer who are often missed, such as underrepresented minority groups or those who live in areas with restricted health care access.

Shield is "the first of, I think, a whole series of tests that we're going to be seeing coming up for screening for not only colon cancer but also for breast cancer, lung cancer, liver cancer," Grady said.

Four years later, tests show Gormly is cancer-free. He hopes his experiences help others who may be tempted to skip colon cancer screening.

"I hope that as a result of this [speaking up]," he said, "someone else tries it and has the same success I did."

According to data from the Centers for Disease Control and Prevention (CDC), 301 people in the U.S. have had confirmed measles infections this year, as of March 13. Additional, probable cases have been reported by various states, but they've yet to be independently confirmed by the CDC.

Kids under 5 years old account for 34% of the confirmed measles cases, with a further 42% affecting children and teens ages 5 to 19. In total, 17% of the cases have resulted in hospitalization.

There has been one confirmed death related to the outbreaks, and a second remains under investigation. The first fatal case was in an unvaccinated school-age child in Texas, marking the first death from measles in the U.S. since 2015. The second deadly case was reported in a New Mexico resident by local health authorities, but the CDC has yet to conclude its own investigation of the case, which would help confirm its connection to ongoing outbreaks.

Related: US measles outbreak tops 300 cases — what to know about the disease

The vast majority of the confirmed measles infections — 95% — have been in people who were unvaccinated or had unknown vaccination status. Additionally, most of the infections have been reported in Texas, with data from the Texas Department of State Health Services showing that 279 measles cases were identified between late January and March 18.

Experts say the Texas outbreak is likely related to low rates of vaccination in the state. For instance, data suggest that around 18% of school-age children in Gaines County have been exempted from at least one vaccine, and 191 measles cases have occurred in that county so far. Meanwhile, Gaines' neighboring counties of Dawson, Yoakum, Terry and Martin have reported 11, 11, 36 and 3 cases, respectively.

As measles continues to spread, here's what to know about the protection of the measles vaccine, how long it lasts, and how to know if you're immune to the disease.

How effective is the measles vaccine?

Measles can be prevented with the MMR vaccine, which protects against measles, mumps and rubella; or the MMRV vaccine, which additionally protects against the chickenpox-causing varicella virus. The CDC recommends that children receive their first dose of the MMR or MMRV vaccine between the ages of 12 and 15 months and their second dose between 4 and 6 years old.

(For measles protection, the MMR vaccine is generally recommended over the MMRV vaccine, because it's less likely to trigger fevers in children. For those who get the MMR shot, a separate vaccine is recommended to protect against chickenpox (varicella).)

Unvaccinated older children and adults are also advised to receive two doses of a measles vaccine, at least 28 days apart.

One dose of the MMR vaccine is 93% effective at preventing measles, while two doses are 97% effective, according to the CDC. The MMRV vaccine offers the same level of measles protection.

"It's probably one of the best vaccines that we have," Michael Head, a senior research fellow in global health at the University of Southampton in the U.K., told Live Science in an email.

"For example, the COVID-19 vaccines are very good at reducing mortality, but less good at preventing a mild COVID-19 infection," Head said. The measles vaccine is highly protective against measles infections of all severity levels.

Measles was declared eliminated in the U.S. in 2000 thanks to widespread vaccination against the disease. The CDC defines "elimination" as the "absence of continuous disease transmission for 12 months or more in a specific geographic area." Measles is not yet "eradicated" worldwide, meaning it still spreads regularly in other countries and can be imported to the U.S.

How long does the MMR vaccine's protection last?

The MMR vaccine provides long-lasting measles protection for most people, with immunity typically being lifelong after two doses, according to the CDC. However, one 2024 study published in the journal The Lancet Public Health reported that measles immunity does fade slightly over time.

"Like with COVID vaccines, antibody levels do reduce over time," Dr. Peter Chin-Hong, a professor of medicine at the University of California, San Francisco, told Live Science via email. Antibodies are protective immune proteins that appear in the days and weeks after a person receives a vaccine, but these proteins are expected to disappear over time.

"However there is likely continued immunity with memory immune cells that can be activated as needed (as we have seen in COVID vaccines)," Chin-Hong added. When exposed to the measles vaccine, the body generates "memory" cells in the immune system, which can quickly mount an immune response and make new antibodies if a person encounters the measles virus.

"In general, protection once immunized against measles, wanes very little," Chin-Hong said. The Lancet study suggested that, on average, measles immunity waned by about 0.039% per year after the age of 5.

Related: 'A political division, not a physical one, determined who got measles and who didn't': Lessons from Texarkana's 1970 outbreak

Does catching measles give you lifelong immunity?

Yes, if a person survives a bout of measles infection, they typically have lifelong immunity against the virus. However, even as the immune system mounts a powerful response against measles, its guard against other infections gets lowered.

Many studies find that measles infections induce a kind of "immune amnesia," in which memory cells tasked with remembering pathogens are lost and the body is unable to rev up its antibody responses, as it used to. This leaves a person at increased risk of other infections for years following their brush with measles.

Other complications of measles infection include a rare but deadly central nervous system condition called subacute sclerosing panencephalitis (SSPE), which can develop seven to 10 years after the infection. Some people can also experience brain swelling (encephalitis) during a measles infection, which can cause convulsions, permanent hearing loss and intellectual disability.

The measles vaccine provides lifelong immunity against the virus without these dangerous complications associated with measles infection.

Is there a way to check if you're immune to measles?

If you've received two doses of the MMR vaccine, you're considered immune for life in most cases. Additionally, if you've had a confirmed case of measles in the past, you're likely immune for life.

If someone is still unsure whether they've either been vaccinated or had the disease, there's a test that checks for measles-specific antibodies in your blood. The type of measles antibody it screens for belongs to a broad class called immunoglobulin G (IgG), which protects the body from infection by binding to pathogens.

If enough measles-specific IgG antibodies are present, compared to a standard threshold, a person has immunity.

"You can check an antibody level with the help of a health care provider," Chin-Hong said. The test will give you a number back that's called a "titer"; this is a measure of your antibody levels. However, the test will not pick up memory cells, Chin-Hong said, so it could miss that additional layer of evidence that you're immune to measles.

Should anyone get a booster for measles, if they've been fully vaccinated in the past?

If a person is unsure about how protected they are against measles, they can get a booster shot of the vaccine to bolster their immunity.

"It is perfectly safe to have another dose," Head said. "The recommendation to get an extra dose will typically come from public health teams, and it's always best to see the advice of a healthcare worker if anyone is unsure."

If someone has had two doses of the measles vaccine in their lifetime, there is likely no need for a booster shot. The exception is a group of people who received the measles vaccine in the 1960s, who would need an additional MMR vaccine to ensure their protection.

That's because the measles vaccine used in the U.S. between 1963 and 1967 was less effective than modern measles vaccines. Unlike the current shots, which contain live-but-weakened viruses, the old shot contained an inactivated virus, so it was completely "killed." In response to the old vaccine, the immune system did not develop long-lasting memory cells, unlike the vaccines used today. Many people who received the old vaccine lost their immunity within a few years, leaving them vulnerable to measles later in life.

In addition to people who received only this old vaccine, anyone who has gotten only one dose of the MMR or MMRV vaccine is recommended to get the recommended second dose.

The CDC started recommending two doses of the MMR shot in 1989, Chin-Hong noted, so those vaccinated before that time may need a second dose.

Individuals traveling to areas experiencing measles outbreaks, including within the U.S., can also consider getting another dose even if they're fully vaccinated, Chin-Hong said.

Additionally, health care workers, immunocompromised people and those who live with them, and college students should check their vaccination records to confirm they've received two MMR doses, and perhaps get an immunity test if they are unsure, Chin-Hong suggested. Individuals can speak with their health care provider about getting a booster shot, if they're interested in receiving one.

Can vaccinated people still catch measles sometimes?

Fully vaccinated people may still catch measles, but only in rare circumstances.

About 3% of fully vaccinated people may still develop measles symptoms after an exposure to the virus, according to the CDC. However, people who have been fully vaccinated tend to experience milder symptoms than unvaccinated or partially vaccinated individuals, and they are also less likely to spread the virus to others.

These "breakthrough" cases become more likely in the context of large outbreaks or high-exposure settings — when an individual has prolonged, close contact with an infected person. About 5% of total measles cases in the U.S. are breakthrough cases, according to the CDC.

Additionally, people with weakened immune systems — due to medical conditions or medications — might not maintain full protection, even if they're fully vaccinated. So they can be more prone to breakthrough cases.

In the current Texas outbreak, there were a "handful" of people who contracted measles after having only one shot," Chin-Hong noted. In a study that looked at measles cases in California between 2000 and 2015, most of those infected were unvaccinated, but 11% of the total cases were among people who had gotten two doses of measles vaccine. The fully vaccinated group did have milder disease, however.

How high do vaccination rates in a community need to be to reach "herd immunity"?

Herd immunity refers to when a high percentage of a population is immune to a disease, making it difficult for the infection to spread. Reaching this collective level of immunity protects even those who can't be vaccinated, such as newborn babies, pregnant people or immunocompromised people.

Measles is one of the most contagious diseases in the world, and because of that, at least 95% of a given population needs to be immune to prevent major outbreaks.

"Measles is so infectious, with very high levels of transmission. Typically, we refer to 95% coverage as the magic number of that 'herd immunity threshold,'" Head told Live Science. "At this level of coverage, there may still be individual case[s], but the majority of the population is protected, and the outbreaks will remain small and very localised."

MMR coverage among U.S. kindergartners has declined in recent years, according to the CDC. In the 2019-2020 school year, 95.2% of kindergartners had received two doses of the MMR vaccine, but in the 2023-2024 school year, that coverage dropped to 92.7%. That marked the "fourth consecutive year" that national coverage had been below the targeted 95%.

Several states — including Arizona, Utah, Colorado, Oklahoma, Georgia and Florida — had less than 90% coverage during the 2023-2024 school year.

The study could help reveal key factors that help some individuals ward off disease and survive to extremely old ages, scientists say.

Before her death in a nursing home in Catalonia, Spain, Branyas held the record for the world's oldest living person for about a year and a half. Now, a study of urine, blood, stool and saliva samples collected from Branyas in the last year of her life reveals she had a number of factors that potentially protected her against disease. These include genes associated with immune function, fantastic cholesterol levels, and a high level of inflammation-fighting bacteria in her gut.

The study was posted Feb. 25 to the preprint server bioRxiv and has not yet been peer-reviewed.

Related: Extreme longevity: The secret to living longer may be hiding with nuns... and jellyfish

"One of the goals of the study was to see and find an explanation for this separation between extreme longevity and being very old, but at the same time not having the diseases of the old," study lead author Manel Esteller, a cancer epigeneticist at the Josep Carreras Institute in Spain, told Live Science.

Notably, however, not all researchers are convinced that studying supercentenarians — people ages 110 or older — is a fruitful method of understanding longevity. That's partly because the actual ages of these individuals have been called into question.

The biology of longevity

According to the Guinness Book of World Records, one entity that validates old-age records, Branyas was born in San Francisco in 1907 and lived in Texas and Louisiana before moving to Spain in 1915 with her Spanish-born parents. Other than hearing loss and mobility issues, she remained healthy and cognitively sharp until death.

Esteller and his colleagues investigated Branyas' genes, immune cells, blood levels of lipids, and proteins in her tissues, comparing her results to those of younger individuals who had undergone similar testing. For example, they compared Branyas' genetic results to those of 75 other Iberian women in the 1000 Genomes Project, an effort to map variation in the human genome.

This comparison revealed seven rare genetic variants in Branyas' genome that had never been detected in European populations.

These variants, or distinct versions of genes, were related to cognitive function, immune function, lung function, heart disease, cancer and autoimmune disorders. They may have protected against these diseases and improved organ function, the scientists suggested.

They also found that Branyas had excellent mitochondrial function, meaning the powerhouses that provide cells energy worked better than those of younger women. She also had healthy cholesterol levels and a high production of proteins that are beneficial for immune function.

And based on her stool samples, her gut microbiome was distinct from that of 61- to 91-year olds previously studied. In particular, she showed a high level of actinobacteria, which typically decline in old age. Bacteria of the genus Bifidobacterium, which are known to excrete anti-inflammatory compounds, were especially prevalent. This contrasts the "typical decline of this bacterial genus in older individuals," the study authors noted.

"She had this bacteria in the gut that protected against inflammation and she had this bacteria for two reasons," Esteller theorized. "The genome was very welcoming of the population, but [it was] also due to her food." Branyas reported eating three yogurts a day, he said; fermented foods like yogurt contain probiotics, or living microorganisms that can replenish and maintain the gut microbiome.

A molecular clock

Another intriguing finding was a schism between the molecular markers of aging in Branyas' body and her chronological age.

When people age, structures at the ends of their chromosomes, called telomeres, become progressively shorter. Telomeres help prevent DNA from fraying, which would contribute to cellular aging and cancer.

As expected for someone of an extreme age, Branyas' telomeres were almost nonexistent, Esteller said. She also had a large population of a particular type of immune cell, which is typical in older people.

In these two ways, Branyas' biology looked very old — but another marker of aging on her DNA looked strangely young, the team found.

Related: Worldwide, the life-span gap between the sexes is shrinking

As a person ages, DNA accumulates a bunch of molecular tags on its surface, called methyl groups. The methylation of DNA can act like a "clock," showing how physiologically aged a person is. Branyas' clock looked like that of someone between age 100 and 110, about a decade younger than she was at death.

In that respect, "her cells still feel like they were centenarian cells," Esteller said.

What does the study tell us about aging?

An accumulation of many little genetic benefits and lifestyle choices may enable extreme longevity, Esteller concluded. Given the study's findings, "maybe we can think about interventions now," he said, including potential drugs to increase life span.

But there may be a caveat to this research and other studies like it: the ages of the subjects it focuses on.

The validation of extreme old age is controversial. For example, in 1997, the oldest person to have ever lived, Jeanne Calment of France, died, and her age was validated by longevity organizations and the Guinness Book of World Records at 122 years old. But critics have since cast doubt on the veracity of that claim, suggesting Calment actually died in 1934 at the age 59.

They contend that her daughter, Yvonne, took on her identity to evade taxes — and in doing so, she inadvertently became the purported oldest person ever. (If these critics are right, the woman who died in 1997 was actually only 99.)

Another study, which is currently under peer review, argues that the problems with old-age validation go far beyond Calment. This research, first released as a preprint in 2019, suggests that regions with the highest reported proportions of extremely old residents are disproportionately poor and unhealthy.

"It doesn't make sense that this level of poverty would predict good health at any age," said Saul Newman, a scholar at the Oxford Institution of Population Aging and co-author of that research.

What does predict high numbers of very old people, Newman found, is poor record-keeping. For example, U.S. states established birth certificate systems at different times, and the number of people ages 110 and older drops by an estimated 69% to 82% after that record-keeping improves.

Often, people born before such documentation was de rigueur might not even know their true ages, Newman told Live Science. In poor regions, people might also have been motivated to tack years onto their age or take on the identity of a deceased relative to receive a pension.

In Branyas' case, she was born a little less than two years after statewide birth certificates came to California in July 1905. Esteller and colleagues relied on the work of age-verification organizations to validate Branyas' age and did not have direct access to her documents.

When asked, a representative for the Guinness Book of World records provided Live Science with general information on the organization's methods.

"For age-related record titles, the guidelines include requests for government issued documents and further proof to substantiate the claim," the representative wrote in an email to Live Science. "Exact information on these guidelines is only available to applicants and/ or legal representation of them."

The hazy nature of old-age records makes interpreting research on the oldest of the old difficult, Newman said. That Branyas' epigenetic clock suggests she was between 100 and 110 could indeed suggest that she was a 117-year-old who aged unusually slowly — or it could suggest that her paperwork was wrong, and she was between 100 and 110 when she died, he said.

"How do you distinguish between those two cases?" he said. "That’s the central problem. You don't know."

On the other hand, Branyas did undeniably reach old age in enviable health, even surviving a bout of COVID-19 in 2020. Thus, her biology might still help researchers distinguish between changes associated with healthy aging and changes associated with disease.

"For the first time you have biomarkers that can tell you your age, but other biomarkers that can tell you your pathology," Esteller said. "And these are two different things."

Affected populations: Babesiosis is a rare and potentially fatal parasitic disease that destroys red blood cells, the cells that supply tissues with oxygen from the lungs. The disease, which is spread by ticks, occurs worldwide, including in the United States and Europe.

Fewer than 3,000 cases of babesiosis are reported annually in the U.S., and they most commonly occur between May and September in the upper Midwest and Northeast, including in Minnesota, Wisconsin, Connecticut and New York. Cases tend to rise in the spring and summer as this is when people are most likely to be in contact with the ticks that spread the disease.

Causes: Babesiosis is caused by microscopic parasites that belong to the genus Babesia. These parasites usually infect cattle and are spread between animals by ticks that eat the blood of different hosts.

Related: Tick-borne parasite is spreading in the Northeast, CDC says

Once inside the body, Babesia parasites invade and destroy red blood cells. This severely limits the ability of these cells to supply tissues with oxygen.

While more than 100 species of Babesia parasites have been identified, overall, only a few species are known to infect humans.

In the U.S., most babesiosis infections are caused by a parasite species called Babesia microti and are spread by blacklegged ticks (Ixodes scapularis), also known as deer ticks. These ticks are typically found in wooded, brushy or grassy areas.

In rarer instances, Babesia parasites can be spread from one person to another via contaminated blood transfusions, and they can also spread from mother to fetus across the placenta.

Symptoms: Most people exposed to Babesia parasites don't have any symptoms of babesiosis; this is especially true for young, healthy people.

However, in individuals who have weakened immune systems or who are over the age of 50, the parasites can trigger severe disease. People who have had their spleen removed are also more vulnerable to serious infections than the average person, because the spleen normally helps remove infected red blood cells from the body.

Typical symptoms of babesiosis include fever, chills, sweating, muscle aches and pains, as well as swelling of the liver and spleen and having a low level of red blood cells in the body. Symptoms usually emerge within one to four weeks of a person being infected with Babesia parasites, and they can last for several days after onset.

Serious cases of babesiosis can cause multiorgan failure and death, as tissues are starved of oxygen.

Estimates for death rates from babesiosis vary considerably between studies. However, surveillance data gathered in 2019 by the Centers for Disease Control and Prevention (CDC) found a 0.57% death rate among patients in the U.S.

Death rates may be closer to 20% in patients who belong to high-risk groups, even when they receive treatment.

Treatments: Patients who don't have symptoms of babesiosis usually don't require treatment, as the immune system will typically clear the parasites away within one to two weeks.

In symptomatic patients, the main treatment for babesiosis is a combination of antiparasitic drugs and antibiotics. The latter drugs are primarily used to treat bacterial infections, rather than parasitic infections, but certain kinds of antibiotics, such as clindamycin, can also be effective against parasites.

Patients who are very sick may also require a blood transfusion to replace their damaged and infected red blood cells.

The best way to prevent babesiosis is to avoid areas where ticks live, according to the CDC. If you are in those areas, there are precautions you can take to avoid tick bites.

We live in places that will be flooded by rising sea levels. We have food production systems dependent on specific climates. And we have built economic structures, trade relationships and social dynamics contingent on certain temperatures.

What's more, we are not alone in this world, and the rapidly changing climate is a threat to the flora and fauna with whom we share this planet. Some of us think this is a problem — although admittedly not all of us.

The key questions then are: How fragile are systems to a changing climate? What are the costs of the impacts or shocks to the system (such as relocating people from places underwater, or victims of extreme weather events that are made more likely by climate change)? What are the costs of adapting to these impacts? How do we negotiate the equity and distributional impacts of these effects? And crucially, what are the costs of preventing these impacts to begin with?

That is the climate discourse in a nutshell. Except for heat. Heat is a different story because we cannot live above a certain heat level.

Of course, the heat story is driven by climate change, so at first glance it may seem I am making an artificial distinction here. Global warming is heat and heat is global warming. But the reason is that it creates an almost unmanageable risk, one incapable of being mitigated by adaptation, at least within the current technological paradigm.

This is different to almost any other effect from climate change. We can maintain habitats below sea level, the Netherlands being a perfect example, through dams and adaptation. Perhaps we would not be able to do this everywhere, and perhaps we would decide that we couldn't be bothered — economically speaking — to do this, but we at least have the means.

We can change food production patterns, our economic activity cycles, we can irrigate, we can create water, we can do all these things. Some have prohibitive price tags and come with dramatic non-financial costs to health, cultural capital and societal welfare. But they can be done.

Related: 200,000 Americans could die of temperature-related causes each year if global warming hits 3C

Heat is the final boss. Heat is a different beast. Heat deaths in and of themselves may not appear as a particularly new or novel phenomenon. They happen everywhere, as the frail, the ill and the old are unable to regulate their body temperatures during hot summers.

And heat deaths can also happen to the young. One of the first "proven" victims of climate change is a 6-year-old boy from Toyota, Japan, who collapsed in a park on a morning field trip, and was dead by the afternoon.

When I think of the heartbreak of our indifference, I think of him. These kinds of deaths will increase in frequency through climate change but, of course, as any self-respecting climate sceptic or denialist will tell you, we can also expect fewer deaths from cold temperatures.

Indeed, there is some reason to believe that from a pure temperature perspective, temperature-related mortality has in fact decreased in the past decades, not just because of improved adaptation, but also because of warmer winters.

Over time, that pendulum — as we near 1.5 and 2 degrees Celsius (2.7 to 3.6 degrees Fahrenheit) global warming above pre-industrial levels — will swing in the other direction, with up to 10 million annual climate deaths by the end of the century, according to some estimates (not counting the indirect deaths from climate poverty, conflict and so on).

What will be new about heat deaths is the extent to which the lived environment will become physically uninhabitable for everyone, old and young, middle-aged, healthy and ill.

Extracted from "The Pocket Guide to Planetary Peril" by Jakob Thomä (WH Allen, £16.99)

Designed for serious outdoor and fitness enthusiasts, the Amazfit T-Rex 3 promises up to 27 days of battery life, top-notch durability, dual-band GPS, maps, an altimeter and many other features that can come in handy when exploring the great outdoors. You can even take it diving — the Amazfit T-Rex is waterproof to 328 feet (100 meters) and can sustain free dives of up to 147 ft (44.8 m). This rugged watch also comes with over 170 sports modes, voice control, AI coaching and phone notifications.

All this, yet it costs just $279 and is frequently on sale. The Amazfit T-Rex 3 has the potential to be one of the best budget fitness trackers on the market right now.

Amazfit T-Rex 3 smartwatch review

Amazfit T-Rex 3: Design

• Durable and waterproof (including diving)
• Big, chunky and “masculine”
• Removable silicone straps

The Amazfit T-Rex 3 is made to last. It features a tough stainless steel bezel, thick silicone straps and a screen covered with scratch-resistant Gorilla glass, plus it comes with certifications that prove its extensive durability. As we mentioned before, this watch is rated 10ATM, meaning it is waterproof for up to 328 ft (100 m) and it is suitable for freediving up to 147 ft (44.8 m) thanks to its EN13319, ISO 6425 and GB/T 18828 certifications. The Amazfit T-Rex 3 can also withstand temperatures from 158 to -22 degrees Fahrenheit (70 to -30 degrees Celsius). That is impressive, because even some of the best fitness trackers do not have such top-end specs.

We tested our Amazfit T-Rex 3 for about two months and can attest to its toughness. While admittedly we did not go to extremes with the testing process (we are not professional divers), the watch did not sustain any scuffs, scratches or wear-and-tear damage. Cold February temperatures, rainwater or hot showers did not faze it either.

We also found it surprisingly comfortable to wear. The Amazfit T-Rex 3 weighs a solid 2.4 oz (68.3g) without a strap so is heavier than most of the best Garmin watches, for example, but it did not weigh our wrist down. The silicone straps were thick yet soft, and they managed to keep our watch firmly in place without aggravating the skin. We also liked that they were removable. The Amazfit T-Rex 3 comes with a strap-changing kit, and you can buy plenty of different straps online if you fancy a change.

That said, we did not really warm to the chunky design of our Amazfit T-Rex 3. The watch is just too big to be worn comfortably in bed, and unlike most mainstream models, it is only available in one size. We were not convinced by its overly rugged looks, either. While this watch would pair well with muddy boots and climbing gear, it may clash with more casual clothing. The Amazfit T-Rex 3 is somewhat impractical for 24/7 wear.

Amazfit T-Rex 3: Display

• 1.5-inch AMOLED display
• Good visibility in bright conditions
• Navigation takes some getting used to

The 1.5-inch AMOLED display definitely warrants a mention. It is pleasantly bright and colorful, and its large size makes it easy to read. The display can also be customized with hundreds of watch faces to suit your mood, style and tracking preferences. This is a major bonus point for us — we like wearables to reflect the user's goals and personality.

More importantly, the display showed good visibility in bright or low-light conditions, even though the pictures of our T-Rex 3 may not necessarily show that (the flash produced excessive glare so we opted for natural light instead.) We also did not experience lags or any other problems with touchscreen responsiveness.

What we were slightly surprised by was its confusing navigation. It is slightly less intuitive and user-friendly than other Amazfit watches we tested, even though all of these devices share largely the same layout. However, finding different features and settings got easier the more we used the watch.

Amazfit T-Rex 3: Features

• Robust fitness-tracking features
• Dual-band GPS, altimeter and compass
• Mini apps for download from the Zepp App

The Amazfit T-Rex 3 features several sensors: An optical sensor for tracking heart rate and blood oxygen levels, an accelerometer and gyroscope sensors for assessing movement, a compass and barometric altimeter for geolocation, and finally, an ambient light sensor and body temperature sensor. The Amazfit T-Rex 3 also features dual-band GPS positioning, Wi-Fi connectivity and Bluetooth connectivity. It is a tracker in the full sense of the word.

This watch features more than 170 workout modes, personalized training plans and detailed post-workout summaries of your recovery time, training intensity and other key performance metrics. Amazfit does a good job of translating complex metrics into more digestible health advice, and T-Rex 3 is no different. It may have a more in-depth approach to fitness tracking than its less "technical" siblings Balance and Active, but it still manages to keep things relatively easy to understand. This may be particularly useful for beginners and those looking for training guidance.

The Amazfit T-Rex 3 also has a speaker and a microphone so you can answer texts from your wrist, as well as other smartwatch features. For example, it can pay for your shopping with the Zepp Pay contactless payments app, or help you with a range of day-to-day activities — a host of mini-apps is available for download from the connected Zepp app, including a Climbing difficulty calculator, Hydration advice or Pill reminder.

Last but not least, the Amazfit T-Rex 3 has plenty of features to satisfy outdoor enthusiasts, from dual-band GPS and air pressure monitoring to on-watch topographic maps and ski trails. In that regard, it easily rivals many of the premium Garmin and Apple watches.

Amazfit T-Rex 3: Performance

• Up to three weeks’ battery life
• Good GPS and fitness-tracking accuracy
• Strength-tracking features may be unreliable

According to the brand, the Amazfit T-Rex 3 lasts up to 13 days in "heavy use", up to 27 days in "typical use" and up to 180 hours with "continuous outdoor GPS activity" — and that rings true. Our typical use would include continuous heart tracking, hour-long workouts on most days of the week and sleep tracking almost every night, and under these conditions, our watch lasted on average two to three weeks on a single charge. We did not have the opportunity to test if it lasted 180 hours with GPS on, but battery usage in that mode seemed consistent with the claim.

The tracking in the T-Rex 3 watch was largely accurate, especially with sleep, step count and certain sport-specific metrics (stroke rate in indoor rowing, for example.) GPS navigation also seemed to work well for us, locating our position with a good degree of accuracy and in a reasonable time. However, we only had the opportunity to test the watch during walks in towns and other populated areas — we can't vouch for the accuracy of its GPS in any other environments.

The Amazfit T-Rex performed well in our heart rate test, too. We did an hour-long workout wearing both the watch and a Polar H9 chest-strap heart rate monitor, then compared the measurements between the devices. The heart rate was relatively accurate during rest and moderate activity, but it became slightly less reliable with high-intensity exercise. However, these results are consistent with the heart rate measurements given by more premium fitness trackers.

The only performance-related issue we experienced was unreliable movement tracking during strength-based workouts. The Amazfit T-Rex 3 promises to "intelligently count your reps, sets and rest time" and evaluate your movement based on stability, rhythm and other metrics. In our experience, this feature missed the mark on all accounts, with wildly inaccurate estimations and inconsistent performance during almost every resistance workout.

Amazfit T-Rex 3: User reviews

The Amazfit T-Rex 3 was rated 4.4 out of 5 stars at Amazon, with 74% of users giving it five stars. Positive reviews praised this watch for its rugged build, long battery life, large display, ease of use and value for money.

One happy user said: "I used to work for a major smartwatch company (which will remain nameless) writing manufacturing test software and running the data analytics team. [...] I would have to say that this T-Rex 3 watch blows away any of the smartwatches I have seen in my previous company at a reasonable price point. It even has a more comprehensive feature set than I have seen on my Garmin Venu 2 which I use every day for my workouts."

Mixed opinions were expressed on the looks and accuracy of sleep tracking. Negative reviews, on the other hand, tended to revolve around individual faulty units. One customer concluded: "Flimsy rubbish. Had I bought this myself I'd have returned it immediately. Watch feels like it's out of a Lucky Bag. Avoid like the plague."

Should you buy the Amazfit T-Rex 3?

✅ Buy it if: You want a rugged outdoor smartwatch that can give you an excellent run for your money. For less than $280, the Amazfit T-Rex 3 offers the build, functionality and performance of some of the best premium mainstream models.

❌ Do not buy it if: You want something more stylish and discreet, or if you are looking for a basic fitness tracker. This rugged watch may prove too big and chunky for comfortable sleep tracking or formal clothing, and its wide range of features may be redundant for the average gym-goer.

If the Amazfit T-Rex 3 is not for you

The TicWatch Atlas is a great alternative to the Amazfit T-Rex 3. This rugged outdoor watch boasts similar durability, features and tracking capabilities, but it looks better and costs only $70 more.

Looking for something more premium? The Garmin Fenix 8 is a perfect option here. This smartwatch is one of the best outdoor wearables on the market, and its $1,000 price tag fully reflects that.

For those looking for something smaller and simpler, we would recommend the Fitbit Inspire 3. This fitness band is stylish and comfortable to wear, and it has everything you may need for basic daily fitness tracking.

Amazfit T-Rex 3: How we tested

We spent two months testing the Amazfit T-Rex 3 smartwatch, looking at its design, features, tracking performance, connectivity with third-party devices and ease of use. We wore it during the day, while sleeping and when doing a range of workouts, from leisurely walks outdoors to high-intensity cardio and heavy weightlifting in the gym.

Finally, we assessed the accuracy of our Amazfit T-Rex 3 by comparing its heart rate measurements with the data we obtained using a Polar H9 chest-strap heart rate monitor.

In "Everything Is Tuberculosis: The History and Persistence of Our Deadliest Infection" (Crash Course Books, 2025), John Green recounts these unsung ways in which TB shaped history. He also highlights how public perception of the disease has shifted through time. TB was once seen as a romantic condition that rendered people with the illness "beautiful," "waiflike" and "sensitive," but the illness later became seen as a stigmatizing disease of poverty.

And while we now have a cure for TB, "the disease is where the cure is not," Green notes, paraphrasing a Ugandan doctor who said the same about HIV/AIDS treatments. Annually, there are more than 10 million cases of TB and 1 million TB deaths worldwide, and most of these cases and fatalities occur in low- and middle-income countries.

Green is one-half of the vlogbrothers on YouTube, co-creator of the educational series Crash Course, and author of the bestselling books "The Fault in Our Stars" (Penguin Books, 2012) and "The Anthropocene Reviewed" (E. P. Dutton, 2021), among others. Live Science spoke with him about his latest book, its featured subject, TB survivor Henry Reider, and the uncertain future of efforts to end TB worldwide.

Nicoletta Lanese: In the book, you say that you initially thought of TB as a disease of the past — of "19th-century poets." How was it to have that idea dispelled through writing the book?

John Green: If you'd asked me in 2018, "What are the biggest infectious health problems facing the world," I would have said, "I don't know, malaria, HIV, typhoid, cholera." I would have been so far down the list before I said tuberculosis, even though it turns out tuberculosis is the deadliest infectious disease in the world and sickens over 10 million people every year.

To some extent, that's been a throughline throughout history — when Robert Koch was declaring that he'd discovered that TB was infectious, he almost seemed defensive. He said, "I know we're more afraid of cholera and plague, but actually tuberculosis is a much bigger deal."

I just had no idea that tuberculosis was a crisis until I visited a TB hospital in Sierra Leone in 2019. … [There] I met a young boy named Henry Reider, and that kind of changed the course of my life.

NL: Henry is a big focus of the book. For those who haven't read it yet, could you share a bit about him?

JG: Henry and I met at that hospital in Sierra Leone, and when we arrived, he just grabbed me by the T-shirt and started walking me around the hospital. He seemed to be about the same age as my son, who was 9 at the time, and he also shares a name with my son. They [now] call each other "the namesakes."

He walked me all around the hospital, showed me the lab, showed me the wards where patients were staying. I was really astonished by how many people were sick and how sick they were. And we finally made our way back to where the doctors were, and they sort of shooed Henry away and I said, "Whose kid is that?" And they said, "He's a patient, and he's one of the patients we're most concerned about."

It turns out, he wasn't 9. He was 17 — just he'd been stunted by malnutrition and by TB.

He and I have become really good friends and through the process of reporting this — like, I'm not a good reporter. I don't know how to have a distance between the reporter and the subject, as I try to acknowledge in the book. He inspired the book in many ways because I think if I hadn't met Henry that day, I probably wouldn't have become obsessed with tuberculosis.

NL: And how is Henry doing now?

JG: He's very excited about the book. He's a junior at the University of Sierra Leone, Sierra Leone's best university, and he's studying human resources and management and doing really, really well.

However, it is also true that like so many people whose lives are marginalized, his life is made much more fragile by the recent cuts to USAID, and his life is made much more challenging by the recent cuts to USAID. That's been a constant topic of conversation between him and me over the last few weeks.

Related: 'It is a dangerous strategy, and one for which we all may pay dearly': Dismantling USAID leaves the US more exposed to pandemics than ever

[Although Henry has now been cured of TB], Henry also has other health problems, and he has some long-term consequences from having lived with such serious tuberculosis. Like a lot of people, he depends upon USAID-funded medication in order to survive, and that funding has been canceled.

He and I had a conversation recently where I said, "Look, you know, we'll make sure that you and your mom have access to the medication that you need." And he said, "Thank you, but what about everyone else?"

NL: From your description of him, that seems like a question he would ask.

JG: Yeah, he's an extraordinarily empathetic person. He's a poet. He has what used to be called spes phthisica [meaning "consumptive spirit"], the "tubercular personality." We used to think that people who had this tuberculous personality tended to be sensitive and alive to the suffering in the world and generous and beautiful and lots of other romantic ideals.

NL: In the book, you explore how the perception of TB has changed through time, starting with that romantic, idealized vision of the disease. Could you sum up what you learned?

JG: It's almost like they're two different diseases. It's almost like the disease of consumption [a past name for TB] is different from the disease of tuberculosis. Because at least in Northern Europe and the U.S., consumption was an inherited disease that was associated with being beautiful and having certain personality traits that were desirable. Tuberculosis is seen as a disease of poverty, a disease of filth, a disease of infection. They're very different diseases in the way they're imagined, even though they have the same cause and the same course.

You see this all over the history of tuberculosis, but I think you especially see it in the way the disease was racialized. It was widely believed in the 18th and 19th centuries that only white people could get tuberculosis. And then in the 20th and 21st centuries, it was believed white people were insulated from tuberculosis in some ways and that it's a disease primarily of people of color.

The way that I think about it sometimes is that Charles Dickens wrote that tuberculosis was the "disease that wealth never warded off," and, of course, now it's a disease that wealth entirely wards off.

NL: We've touched on this already, but could you expand on how USAID factors into TB efforts worldwide and what it means for that funding to be disrupted?

JG: We did have ongoing projects I would have liked to highlight. I would have liked to highlight our work in the Philippines with USAID to bring TB down to zero in specific communities to offer a blueprint for how we eliminate TB from the planet. [Beyond our own work], I'd like to highlight the work that has been done to reduce TB death by over 50% in the last 25 years. I'd like to highlight the efforts that are being made by the U.S. government and others to radically reduce the burden of tuberculosis in the most impoverished countries in the world. But we've just abandoned all of those.

The project that we've been working on in the Philippines with Partners In Health and USAID and the Philippine government will continue in some way, thanks to the generosity of the Philippine government. But it won't accomplish its biggest dreams, and that's entirely because of the decision to stop funding essentially all global health services.

I'm confused as to how all of this is happening, but I'm just also heartbroken. I'm hearing every day from people who are having to make horrible decisions about how to ration care.

Related: 10 of the deadliest superbugs that scientists are worried about

NL: And in tuberculosis, continuity of care is very important.

JG: Continuity of care is essential for curing tuberculosis. If someone has even a couple of weeks without access to their medication, it's vastly more likely that their disease will become drug resistant, which is a personal catastrophe because it means that they are much more likely to die of tuberculosis. It's also a societal catastrophe because it means there's much more drug-resistant tuberculosis floating around, having the opportunity to evolve ever more drug resistance.

I think it's important to understand that we've never done anything like this before; we've never suddenly interrupted the treatment of thousands or tens of thousands or hundreds hundreds of thousands. We don't even know how many people's treatment is being interrupted right now because we have no way to count it. … What we're doing to the future of tuberculosis is unconscionable to me.

NL: In a moment when the situation feels so bleak, is there anything bringing you hope?

JG: It's inevitable for me to feel like I live at the end of history because today is the most recent day I've ever experienced, you know, and so this feels like the culmination of everything that came before, but I don't live at the end of history. I live in the middle of history, and this is not the end of the story; this is the middle of the story, and we have to fight for a better end.

That's what gives me hope, and working with people I love. In this work, you get to work with people you care about and whose love and attention is focused in the same direction as yours, and there's a lot of comfort in that for me.

Editor's note: This interview was conducted on Feb. 28, 2025, so it may not reflect recent developments with USAID. The transcript has been lightly edited for length and clarity.

New research in mice shows that the hormone can put embryos in the earliest stages of development into a kind of hibernation state. Once triggered, this process, called "diapause," might allow a mouse mother to delay a pregnancy at a time when resources are scarce — such as while she is still nursing a previous litter of newborn mouse pups.

"The fact that oxytocin had an influence on this was a little bit of a surprise," study co-author Moses Chao, a neuroscientist at the New York University Grossman School of Medicine, told Live Science.

Diapause, in general, is a bit of a mystery. The phenomenon naturally occurs in marsupials, such as kangaroos and possums, and in at least 130 species of mammals, including mice and bats.

It might even occur in humans — it's a difficult phenomenon to track in most human pregnancies, but a few scattered reports from in vitro fertilization (IVF) clinics suggest that, in rare cases, embryos transferred into the uterus might hang out for weeks before actually implanting in the organ. In one case reported in 1996, it took five weeks after embryo transfer for the pregnancy to begin.

Related: Pregnancy may speed up 'biological aging,' study suggests

It's not clear how long diapause can last, Chao said, nor is much known about how embryos enter this state of suspended animation.

Study first author Jessica Minder, a graduate student at the NYU Grossman School of Medicine, was interested in oxytocin's role in diapause because the hormone is also known to be involved in embryonic development and nursing in mammals, including humans.

Minder and colleagues began the work by introducing male mice into the enclosures of female mice that had just given birth, allowing the rodents to mate while the females were still nursing their first litters. The researchers found that the resulting pregnancies lasted about a week longer in still-nursing female mice than they did in mice that were not nursing.

They think this likely reflects a pre-implantation "pause." As mouse pregnancies typically last only 19 to 21 days, the pause reflects a significant delay in the process.

The team then set about exploring how this pause might occur.

In another group of newly pregnant mice, the team used a technique called optogenetics, which uses light to switch on specific neurons, to make the brains of the mouse moms release oxytocin. The researchers timed this stimulation to mimic the pulses of oxytocin seen during nursing.

After five days of this treatment, they removed the mice's uteruses to assess embryonic development. Five of the six mouse mothers had embryos that underwent diapause, as evidenced by a lack of development.

Meanwhile, in a comparison group, pregnant mice who did not have their oxytocin stimulated did not show any signs of diapause.

In another experiment, the team treated early mouse embryos with oxytocin in lab dishes, and that also induced cellular changes consistent with diapause.

Together, the evidence suggested that oxytocin caused embryonic cells to slow their translation of genes into proteins, the researchers reported March 5 in the journal Science Advances. This multistep process involves copying down instructions from DNA into a new molecule, called RNA, that gets shipped to a cell's protein construction sites.

Embryos without oxytocin receptors can still undergo diapause, Chao noted, so there are probably multiple signals that can trigger the pause. However, oxytocin seems to be important for the embryos to survive this arrest.

When the researchers turned off oxytocin receptors in the mouse embryos, they found that only 11% survived diapause, compared with 42% of the embryos with working oxytocin receptors.

This research is an early exploration of the metabolism of early embryos, Chao said. Eventually, a better understanding of these mechanisms might reveal insight into why early miscarriages happen in people and could possibly lead to new fertility treatments.

More work will be needed to understand the biochemical steps that lead from oxytocin stimulation to diapause, Chao said.

The new findings could also be helpful for understanding cell survival more generally, Chao added. For example, half of the nerve cells in the early embryo die as the developing nervous system is refined before birth. However, many of the nerve cells that develop in the womb ultimately last a lifetime.

"Later on [in development], you don't want half your cells dying," Chao said, "so we're very interested in what keeps those cells going."

The symptoms: The teenager was admitted to a hospital in the Netherlands for knee surgery after getting injured while playing soccer. The surgery was successful, but when the patient woke up from the anesthesia, he spoke exclusively in English and insisted "repeatedly" that he was in the U.S. Prior to this incident, he spoke the language only during English class in school.

He did not recognize his parents and could not speak or understand spoken Dutch, his native language. According to a report doctors wrote about his case, the patient had no history of psychiatric symptoms and no relevant medical family history, apart from some instances of depression on his mother's side of the family.

What happened next: The nurse who initially noticed the patient speaking English was not immediately worried by it, thinking the teen was experiencing emergence delirium — a state of confusion that can occur during recovery from anesthesia. However, when medical staff still could not get the patient to speak a single word of Dutch a few hours later, they called for a psychiatric consultation.

Related: Can you forget your native language?

The psychiatric team found the patient relaxed and attentive. He was able to answer questions, albeit in English spoken with a Dutch accent. Later on, he started to give short answers in Dutch but found it difficult to do so.

The diagnosis: The 17-year-old was diagnosed with foreign language syndrome (FLS), which happens when patients suddenly and involuntarily switch to using a second language instead of their native language for a period of time.

The treatment: A neurologist found no abnormalities during a full neurological examination of the patient. Then, 18 hours after his surgery, the teen was able to understand Dutch but still couldn't speak it. Some of the teen's friends came to visit him the day after his surgery, and suddenly, he was able to understand and speak Dutch again.

Because the teen spontaneously started speaking in his native language again, doctors saw no need to run any neuropsychological tests, electroencephalograms (EEG) or other types of brain scans on him. He was discharged three days post-surgery.

What makes the case unique: FLS is rare, with only about nine cases described in medical literature. In most of these cases, the patient was a white male who switched from their native language to another one they had learned later in life; the patients weren't typically bilingual growing up. The race of the patients in two cases was not documented.

The authors of the case report said FLS is rarely seen in children, and they suspected that they were the first to formally document a case of FLS in an adolescent. In total, they found eight reported cases of FLS that were similar to that of their patient, in which the person affected switched to a completely different language rather than speaking in a way that could be perceived as a foreign accent.

This is what happens in a related condition — called foreign accent syndrome — in which people adopt a speech pattern that makes it sound like they're speaking with an accent. The rare condition has often, but not always, been seen in the context of brain injuries.

Exactly why FLS happens is unknown, although there have been other cases in which the syndrome emerges after anesthesia. The case report authors noted that an anesthetic's effects on cognition, as well as the clearance of anesthetic drugs from the central nervous system, can lead to emergence delirium. For that reason, they're not sure if FLS can be classified as a distinct condition or merely a variation of emergence delirium.

The tool could offer new insights into the neuroscience of language, and someday, it could help improve technologies designed to recognize speech or help people communicate, the researchers say.

Based on how an AI model transcribes audio into text, the researchers behind the study could map brain activity that takes place during conversation more accurately than traditional models that encode specific features of language structure — such as phonemes (the simple sounds that make up words) and parts of speech (such as nouns, verbs and adjectives).

The model used in the study, called Whisper, instead takes audio files and their text transcripts, which are used as training data to map the audio to the text. It then uses the statistics of that mapping to "learn" to predict text from new audio files that it hasn't previously heard.

Related: Your native language may shape the wiring of your brain

As such, Whisper works purely through these statistics without any features of language structure encoded in its original settings. But nonetheless, in the study, the scientists showed that those structures still emerged in the model once it was trained.

The study sheds light on how these types of AI models — called large language models (LLMs) — work. But the research team is more interested in the insight it provides into human language and cognition. Identifying similarities between how the model develops language processing abilities and how people develop these skills may be useful for engineering devices that help people communicate.

"It's really about how we think about cognition," said lead study author Ariel Goldstein, an assistant professor at the Hebrew University of Jerusalem. The study's results suggest that "we should think about cognition through the lens of this [statistical] type of model," Goldstein told Live Science.

Unpacking cognition

The study, published March 7 in the journal Nature Human Behaviour, featured four participants with epilepsy who were already undergoing surgery to have brain-monitoring electrodes implanted for clinical reasons.

With consent, the researchers recorded all of the patients' conversations throughout their hospital stays, which ranged from several days to a week. They captured over 100 hours of audio, in total.

Each of the participants had 104 to 255 electrodes installed to monitor their brain activity.

Most studies that use recordings of conversations take place in a lab under very controlled circumstances over about an hour, Goldstein said. Although this controlled environment can be useful for teasing out the roles of different variables, Goldstein and his collaborators wanted to "to explore the brain activity and human behavior in real life."

Their study revealed how different parts of the brain engage during the tasks required to produce and comprehend speech.

Goldstein explained that there is ongoing debate as to whether distinct parts of the brain kick into gear during these tasks or if the whole organ responds more collectively. The former idea might suggest that one part of the brain processes the actual sounds that make up words while another interprets those words' meanings, and still another handles the movements needed to speak.

In the alternate theory, it's more that these different regions of the brain work in concert, taking a "distributed" approach, Goldstein said.

The researchers found that certain brain regions did tend to correlate with some tasks.

For example, areas known to be involved in processing sound, such as the superior temporal gyrus, showed more activity when handling auditory information, and areas involved in higher-level thinking, such as the inferior frontal gyrus, were more active for understanding the meaning of language.

They could also see that the areas became active sequentially.

For example, the region most responsible for hearing the words was activated before the region most responsible for interpreting them. However, the researchers also clearly saw areas activate during activities they were not known to be specialized for.

"I think it's the most comprehensive and thorough, real-life evidence for this distributed approach," Goldstein said.

Related: New AI model converts your thought into full written speech by harnessing your brain's magnetic signals

Linking AI models to the inner workings of the brain

The researchers used 80% of the recorded audio and accompanying transcriptions to train Whisper so that it could then predict the transcriptions for the remaining 20% of the audio.

The team then looked at how the audio and transcriptions were captured by Whisper and mapped those representations to the brain activity captured with the electrodes.

After this analysis, they could use the model to predict what brain activity would go with conversations that had not been included in the training data. The model's accuracy surpassed that of a model based on features of language structure.

Although the researchers didn't program what a phoneme or word is into their model from the outset, they found those language structures were still reflected in how the model worked out its transcripts. So it had extracted those features without being directed to do so.

The research is a "groundbreaking study because it demonstrates a link between the workings of a computational acoustic-to-speech-to language model and brain function," Leonhard Schilbach, a research group leader at the Munich Centre for Neurosciences in Germany who was not involved in the work, told Live Science in an email.

However, he added that, "Much more research is needed to investigate whether this relationship really implies similarities in the mechanisms by which language models and the brain process language."

"Comparing the brain with artificial neural networks is an important line of work," said Gašper Beguš, an associate professor in the Department of Linguistics at the University of California, Berkeley who was not involved in the study.

“If we understand the inner workings of artificial and biological neurons and their similarities, we might be able to conduct experiments and simulations that would be impossible to conduct in our biological brain," he told Live Science by email.

But is this really how it happens? Do sperm really race to the egg?

Yes and no, David J. Miller, a professor in the animal sciences department at the University of Illinois Urbana-Champaign, told Live Science. "The important player in all of this is actually the female reproductive tract."

Sperm do swim during this process, but "the major movement is actually provided by contractions of the female tract," Miller explained. "There are contractions of the uterus, for example, that are much like contractions of the GI tract that can move fluid through the uterus."

A 1996 study illustrated just how efficient these contractions are, Miller noted. Scientists deposited sperm-size beads into the uteruses of 64 women, and some of the beads traveled all the way to the fallopian tubes — where fertilization usually takes place — within minutes.

Related: Are you genetically more similar to your mom or your dad?

It makes sense that sperm would need some extra help, because while the sperm swim in one direction, the egg needs to travel in the opposite direction to meet them, Sabine Koelle, a full professor of anatomy and developmental biology at the University College Dublin School of Medicine and Medical Sciences, told Live Science. The egg can't swim, so instead tiny hairs called cilia help it along .

"Cilia beat to transport the oocyte," or egg, Koelle said. "Because the sperm are coming from the opposite direction, they have to struggle" against the current created by the cilia.

In fact, an individual sperm's movement is less of an effort to move forward and more of an effort to move inward, toward the middle of the tract, Koelle said. If the sperm get too close to the sides, they stick and lose their forward momentum.

However, just because a sperm is the first to arrive doesn't mean it gets to do the fertilizing. "Sperm require some final maturation that occurs in the female tract, and it's time dependent," Miller said. "So the sperm that 'win the race,' so to speak, need more time before they can actually fertilize the egg."

"They may not be there when they've completed that maturation," Miller added. "They might be replaced by some of the other more slowly transported sperm that have had time to complete that maturation."

But even those less-mature sperm are more successful than the vast majority of sperm that get deposited. As the female reproductive tract pushes the sperm along, it also cuts unlucky individuals from the swim team.

"Less than 1% — maybe up to 2 or 3% of the sperm that are actually deposited — make it all the way to where the egg is," Miller said. "A lot of them are flushed back out from the tract. Some are eaten up by immune cells in the uterus, because sperm are foreign."

Up to 70% of sperm don't even make it past the cervix, Koelle noted. "The sperm are stuck there and can't free themselves," she said.

For those few sperm that make it into the fallopian tube, the goal is to get as far as possible and then stick to the wall as they wait for the egg to arrive. This is another place where the female reproductive organs are choosing winners: Scientists have noticed that normal-looking sperm are more likely to bind to the wall, Miller said, and binding to the wall provides some metabolic benefits that increase their lifespan.

Then, once the egg arrives, the fallopian tube — also known as the oviduct — allows only healthy-looking sperm to unstick from the wall. "As soon as a sperm is not OK, the oviduct doesn't release it," Koelle said. "It's the main selector of good sperm."

This isn't a perfect system, of course. " Obviously, we have genetic diseases that come through sperm. So it's not always true that the fittest are the best ones genetically," Miller said.

Every step of the way, the female reproductive tract is doing its best to weed out the less-fit sperm so that only healthy sperm reach the egg. In that way, fertilization is less like a race and more like a job interview.

"There's certain qualifications that you need to be able to apply for the job," Miller said. "But also, the sperm that have those qualifications would have to have them at the time the job is open — the time when the egg is ovulated." But in the end, it's the female reproductive tract that chooses the best candidate.

Some of the best fitness trackers can even use machine learning to give you detailed exercise recommendations based on how your health metrics change over time — not to mention that smart wearables can be invaluable tools for endurance athletes. But how do fitness trackers measure your heart rate, exactly? And how accurate are these measurements? We asked the experts.

Most fitness watches and smart rings depend on a technique called photoplethysmography (PPG). While its name may sound scarily complex, this technology is based on a relatively simple concept — light absorption by the body tissues.

How does photoplethysmography work?

PPG uses optical sensors that detect heart rate by measuring changes in the volume of blood flowing through tiny blood vessels in the skin and underlying connective tissue, Dr. Peter Sogaard, professor of cardiology at Aalborg University in Denmark and chief medical officer at VentriJect, a company which has developed a novel device for measuring cardiorespiratory fitness, told Live Science by email.

With each heartbeat, the heart muscle contracts and relaxes, to force the next portion of blood into circulation. Contracting causes a temporary spike in blood volume and increased pressure on the artery walls, and it is often referred to as the systolic phase of the cardiac cycle. When the heart relaxes between beats, the blood flow decreases — this is known as the diastolic phase. PPG sensors measure these changes in blood volume and pulse pressure (the difference between systolic and diastolic pressure), and then convert these metrics into heart rate measurements, Sogaard said.

PPG sensors detect these changes in blood movement by emitting light at specific wavelengths into the skin. Blood components like hemoglobin, the protein in red blood cells, absorb some of that light. The tracker's photodetector then measures the amount of light reflected back. The more light absorbed by the blood, the higher its volume in the blood vessels — and this is what fitness trackers interpret as a heartbeat, Sogaard said.

"The most commonly used light sources are infrared and green LED," Sogaard said. That is because these wavelengths of light tend to be the most effective at penetrating the skin tissue, according to a 2022 review published in the Frontiers of Physiology. Generally, the accuracy of PPG increases with the light wavelength, the review authors noted. Some optical sensors even combine several wavelengths to improve accuracy.

That is the theory. But how accurate are optical sensors in practice? The answer is less clear.

How accurate is photoplethysmography?

"Multiple factors can affect the accuracy of PPG, from tracker placement and body temperature to skin thickness, motion artifact [distortions caused by movement] and cardiovascular disorders like arrhythmia and peripheral vascular disease [a condition in which the arteries outside of the brain and the heart become blocked or narrowed]," Dr. Masaki Nakamura, a cardiothoracic surgeon at Baptist Health Miami Cardiac & Vascular Institute, told Live Science by email.

For example, optical sensors tend to provide more reliable heart rate measurements during rest and sleep than they do during exercise, according to a 2020 meta-analysis in the Journal of Sports Sciences. Scientists compiled 44 studies that compared the accuracy of PPG fitness to more precise ECG (electrocardiogram) and chest-strap heart rate monitors and found that the biggest discrepancies could be observed with weightlifting, cycling and other high-intensity sports. While most modern fitness trackers use accelerometer-based algorithms to account for rapid movements, motion artifacts can still affect their tracking accuracy.

Skin contact is another factor that can have an impact on PPG measurements, Sogaard said. For example, a device that is too loose or too tight will not allow the optical sensors to get a good reading. Skin temperature can also interfere with PPG. "If the patient has a low temperature, vessels are contracted and measurements become inaccurate," Sogaard said.

Moreover, optical sensors may struggle with detecting heart rate in people with darker skin tones or tattoos. That is because both melanin, the dark pigment in the skin, and tattoo ink can absorb light and reduce the amount of light reflected back to the tracker, according to a 2023 review published in the Journal of Racial and Ethnic Health Disparities.

People with obesity may also struggle with obtaining accurate heart rate measurements. Excess body fat can lead to changes in skin thickness and blood flow, which is why it may affect the accuracy of optical sensors, according to a 2021 review published in the journal Biosensors. The good news is that scientists are working on developing new technologies that would make PPG more accessible for these population groups.

While not without limitations, PPG fitness trackers can be useful for monitoring heart rate in people with certain cardiovascular conditions, according to Nakamura. "Continuous heart rate and blood pressure monitoring can be crucial for cardiac patients to prevent future events like a heart attack, stroke or acute heart failure. The current industry gold standards of blood pressure and heart rate assessment are the manual sphygmomanometer (BP cuff) and the electrocardiogram. However, both these exams can only be measured intermittently and can be affected by factors such as white coat syndrome [a condition when a person's blood pressure is high only when measured in a health care setting], caffeine or stress," Nakamura said.

That said, experts agree that PPG-based heart rate readings should never be regarded as a substitute for clinically validated tests conducted by healthcare professionals.

This article is for informational purposes only and is not meant to offer medical advice.

"Every dollar we spend, every program we fund, and every policy we pursue must be justified with the answer to three simple questions," Rubio said in a State Department press release. "Does it make America safer? Does it make America stronger? Does it make America more prosperous?"

One may take issue with such a narrow view of the value of foreign development assistance, which is essential to the survival of millions of people in regions affected by war, poverty and the impacts of human-caused climate change. But even by this narrow standard, the Trump administration's reckless dismantling of U.S. foreign aid programs makes no sense. In fact, it fails all three of Rubio's tests, making America weaker, less safe, and more prone to shocks that could cripple our economy.

Nowhere is the short-sightedness of the administration's strategy clearer than in the havoc it has brought on the U.S. Agency for International Development. USAID provides development assistance in more than 120 countries, funding projects that bring health services, education, food and clean water to vulnerable communities across the globe. From building schools to aiding in recovery from natural disasters, its work contributes in important ways to the health and economic development of regions that are prone to poverty, conflict, displacement and the political extremism that can often accompany social and economic disparity.

In terms of direct and tangible benefits to the U.S., one of USAID's most critical functions is to fight the spread of infectious diseases that have the capacity to spark a global pandemic. In 2014, for example, USAID deployed teams in West Africa to coordinate the response to a fast-growing Ebola outbreak. A significant part of that response was the establishment of screening protocols for people traveling from the affected region, a key measure in preventing an Ebola crisis in the U.S., which recorded only 11 Ebola cases in that year.

Such pandemic threats have not gone away. Ebola cases are rising in Uganda, and Tanzania recently experienced a deadly outbreak of Marburg virus, which causes severe hemorrhagic fever. Last August, an outbreak of mpox in the Democratic Republic of the Congo triggered the World Health Organization to declare an international public health emergency, signaling renewed concern about a virus that spread to 122 countries in a 2022 outbreak.

Related: Trump executive order calls mental health prescriptions a 'threat' — why?

In other parts of the world, USAID is a critical player in efforts to identify novel forms of avian influenza and other pathogens that have the potential to cause a future pandemic. As part of maintaining this global early warning system, the agency has funded labs and surveillance protocols in more than 30 countries, an investment of more than $900 million in 2023.

While much of this work is carried out far from the U.S., infectious diseases know no borders, and we have seen countless instances of viruses that arise in one part of the world but quickly find their way to other countries. The best way to prevent an epidemic in our own country is to control it at its source.

What is disappearing is our ability to react to such global health threats. USAID had been leading efforts to respond to the mpox crisis in the DRC, committing more than $55 million to orchestrate efforts to screen for the virus and distribute vaccines. However, among the many devastating impacts of President Trump's foreign aid freeze is that this work has stopped. All but six of USAID's 50 staff dedicated to global outbreaks have been fired, and on-the-ground disease response teams have been sent home.

The abrupt withdrawal of staff and financial support has left underresourced health systems such as the DRC's on the brink of collapse, unable to provide even basic health services. These disruptions continue to affect even the programs permitted to continue under the administration's narrow waivers for life-saving interventions.

The administration's announced order to cancel more than 90% of USAID's foreign contracts, effectively cutting nearly $60 billion in assistance, will only deepen these risks. According to USAID documents obtained by Propublica, discontinuation of the agency's services is predicted to lead to surges in cases of malaria and drug-resistant tuberculosis. One million more children will suffer severe malnutrition, and 200,000 more will be paralyzed by polio, according to the report.

In dozens of countries around the world, clinics that provide antiretroviral medications to 20 million people living with HIV — most of which rely on USAID for administrative and logistical support through PEPFAR (U.S. President's Emergency Plan for AIDS Relief) — have been shuttered. According to our research, even just a 90-day interruption in these services will lead to an additional 100,000 HIV-related deaths this year, threatening more than two decades of progress toward ending the global epidemic of HIV and AIDS.

For decades, U.S. leaders on both sides of the political spectrum have recognized the strategic value of these efforts. President John F. Kennedy, who launched USAID in 1961, described foreign aid as "a very powerful source of strength" for the U.S., allowing the country "to exert influence in the maintenance of freedom." Four decades later, President George W. Bush made historic investments in global health a centerpiece of his national security agenda, launching both PEPFAR, the largest commitment to fight a disease in our history, and the President's Malaria Initiative.

These presidents, like countless other leaders over the years, understood that working to secure the health and prosperity of other countries is, in fact, a direct investment in our own national health and prosperity. By contrast, what we see today is a haphazard retreat that will inevitably result in a world that is sicker, less stable and perilously exposed to threats such as climate change or a future infectious disease outbreak. We need only to look at the COVID-19 pandemic to understand how a health crisis that emerges in one part of the world can impact lives and economies across the globe. It is a dangerous strategy, and one for which we all may pay dearly.

Opinion on Live Science gives you insight on the most important issues in science that affect you and the world around you today, written by experts and leading scientists in their field.

However, there is an interesting twist — evidence suggests that elite rowers tend to have notably bigger hearts compared to elite runners.

Take the landmark 1994 study published in the American Journal of Cardiology, for example. One of the biggest of its kind, it investigated structural and functional changes within the heart of 947 elite athletes representing 27 sports disciplines. Scientists used echocardiography — images of the heart obtained with an ultrasound scan — and found that, of all study participants, rowers had the thickest left ventricular wall.

This is the layer of muscle and connecting tissue surrounding the largest chamber of the heart. Rowers also had some of the largest left ventricles during the resting phase between heartbeats, when the heart relaxes and fills with blood. On the other hand, runners did not seem to display such far-reaching changes to their hearts, the study authors noted.

So how does rowing affect your heart, and is it different from running?

While both of these activities challenge your cardiovascular system, they do not do so in the same way, Dr. Bhaskar Semitha, a cardiologist and cardiothoracic surgeon at Fortis Hospital Vashi in Mumbai, India, told Live Science by email. "[This is why] elite rowers tend to have bigger, stronger hearts compared to elite runners, even when they have similar levels of cardiovascular fitness," Semitha said.

The reason lies in the movement itself. Running predominantly targets your legs. Rowing, on the other hand, is a low-impact exercise that simultaneously engages muscles in your legs, core and upper body.

"Rowing is a full-body workout that demands a high oxygen supply, so the heart has to pump more blood per beat," Semitha said. As such, exercising on one of the best rowing machines may force your heart to pump blood more efficiently than if you opted for a jog on a treadmill.

"Over time, this leads to a lower resting heart rate and a higher stroke volume [the volume of blood pumped from the ventricle per beat.] The heart is working less while delivering more oxygen," Semitha said.

This also leads to a significant increase in VO2 max, the maximum amount of oxygen a person can utilize during exercise, which is one of the key markers of performance in cardiovascular exercise. "That's why you will often see rowers with some of the lowest resting heart rates of any athletes," Semitha said.

Rowing and running elicit different heart rate responses even if these activities are performed at the same intensity, according to a 2002 study published in the European Journal of Applied Physiology. Scientists measured the blood lactate concentration — a biochemical marker of fatigue within exercising muscle — in 55 young, healthy men rowing on a rowing machine and running on a treadmill, and found that their heart rate was consistently lower during rowing even when both these exercises were performed with maximum effort.

Why? Again, it is all about the movement. The seated position during rowing makes it easier for blood to flow from the body's lower extremities back to the heart, scientists concluded.

There is a slight twist to the tale, though. Running, even at moderate intensity, is still more effective than rowing for increasing VO2 max, Sergii Putsov, PhD, a professional weightlifter, researcher and head of sports science at coaching service Torokhtiy Weightlifting, told Live Science. "Running forces your body to work against gravity, amplifying oxygen consumption and utilization. Since rowing is less weight-bearing than running, its overall ability to increase VO2 max is slightly lower for people who do not push themselves to high intensity," Putsov said.

Running also tends to cause more dramatic spikes in heart rate, particularly during high-intensity sprints. "[This is why] running puts more demand on arterial flexibility than rowing," Semitha said. "The repeated impact and fluctuations in intensity force the blood vessels to expand and contract rapidly, which can make arteries more elastic over time and therefore help prevent high blood pressure and cardiovascular disease."

So in the rowing vs running debate, which activity wins for cardiovascular benefits? Neither. Both rowing and running are good exercises for boosting stamina and strengthening the heart muscle, according to Putsov.

"However, their effectiveness may depend on your fitness level, specific goals and physical condition," Putsov said. "The full-body nature of rowing helps improve oxygen utilization efficiently without the harsh repetitive impact associated with running. Running, on the other hand, generates repetitive pounding on your joints and requires relatively high initial energy which can be overwhelming for beginners and people with poor cardiovascular fitness."

This article is for informational purposes only and is not meant to offer medical advice.

Research suggests that stressful events can tweak a person's epigenetics — but what happens on a larger scale? How do people's epigenetics change, for example, in a population exposed to upheaval or violence multiple times over generations?

A new study, published Feb. 27 in the journal Scientific Reports, sought to answer that question.

An international collaboration of researchers convened by Rana Dajani, a molecular biologist at Hashemite University in Jordan, published first-of-their-kind results: they found that epigenetic signatures of trauma can be passed down through generations of people. The study was conducted with three generations of Syrian families that experienced the Hama massacre in 1982 and the Syrian uprising that began in 2011.

Related: Sperm cells carry traces of childhood stress, epigenetic study finds

"This is an interesting and fascinating study that emphasizes the importance of considering how traumatic experience can have an impact across multiple generations," Michael Pluess, a developmental psychology researcher at the University of Surrey in the U.K. who was not involved in the work, told Live Science in an email.

A multinational and multigenerational collaboration

Dajani mainly studies the genetics of ethnic populations in Jordan but always had an interest in stress and epigenetic inheritance. There were several studies in lab animals that suggested epigenetic changes can pass from one generation to the next.

However, the question of whether epigenetic signatures of trauma and displacement can pass between generations of people had yet to be answered.

As a daughter of a Syrian refugee, Dajani realized she was in a unique position to probe the question.

"It clicked in my mind, 'Wait a minute; we can actually answer this question because of the unique characteristics and the unique history that the Syrian community has gone through,'" Dajani told Live Science.

Dajani brought the idea to Catherine Panter-Brick, an anthropologist at Yale University with expertise on stress biomarkers and global health, and Connie Mulligan, an epigeneticist at the University of Florida who focuses on childhood adversity. The three scientists spent the next decade partnering on the study.

Connecting with the community

Dajani and Dima Hamadmad, a co-author of the study and a daughter of Syrian refugees, contacted families all over the world mainly through word of mouth. The researchers sat down with the families and listened to their stories; they also explained the science of epigenetics, what they could expect from the study's results, and how these results could bring awareness to their stories.

"They [the families] felt gratified because, first, they understood the science, and second, they felt agency — that they were doing something in response to what happened to them," Dajani said.

"This could have only happened because … I'm a scientist and I'm Syrian. So it's somebody from the community center."

The Hama massacre was an assault by the government on the west-central city of Hama, during which an estimated 10,000 to 40,000 people were either killed or disappeared. The Syrian uprising that began in 2011 resulted in the deaths of hundreds of thousands of civilians protesting the Assad government regime.

It took seven years to find families with three generations of women willing to participate in the study and gather enough samples to meet its criteria. The researchers collected cheek-swab samples from grandmothers who had been pregnant during the 1982 attack, as well as from their daughters and granddaughters.

They also collected samples from mothers who had been pregnant during the 2011 uprising and from their mothers and daughters.

Additionally, the research team found families with daughters where one was a child during the 2011 uprising, and thus had direct exposure to trauma, while the other daughter was still in the womb at the time.

Finally, they took samples from Syrian families that had left the country before either incident, to use as a point of comparison.

"You cannot find three generations of humans who have been subjected to the brutality of war in such a discrete way with grandmothers versus mothers versus children being exposed or non-exposed to war. So that's a very unique design," Panter-Brick said.

Related: Scientists just rewrote our understanding of epigenetics

Epigenetic marks of trauma

An analysis of the samples revealed 21 distinct epigenetic changes in the genome that were unique to those who had direct exposure to trauma. An additional 14 changes seemed to be unique to the grandchildren of grandmothers who were exposed to trauma while pregnant.

Together, these changes occurred at 35 sites along the genome. And the data hinted that, at the majority of those sites, the same pattern of epigenetic changes unfolded regardless of the type of exposure — direct, prenatal or from a prior generation.

Specifically, one common type of epigenetic change is the addition or subtraction of a compound — called a methyl group — from DNA. So across the different trauma types, most of the sites showed methylation in the "same direction," either adding or subtracting.

However, that finding wasn't statistically significant, likely due to the relatively small sample sizes in each group, the authors noted. So the findings bear confirming in larger samples.

"What it seems to say is that there might be a common epigenetic signature of violence across generations, exposures and developmental stages," Mulligan told Live Science.

The analysis also found that children who were exposed to trauma in the womb appeared epigenetically "older" than their chronological ages; this was not seen in other modes of exposure. So-called accelerated epigenetic aging has been linked to a number of health issues, but it's unclear whether the epigenetic changes drive the health problems or simply reflect them.

Mulligan suggested that this aging effect could be the result of trauma exposure during a highly active stage of fetal development, which could explain why it was only seen in the context of prenatal exposure.

What does this mean for human health?

The scientists don't yet know what differences these epigenetic signatures might mean for human health.

Mulligan suggested that the marks "might have allowed humans to adapt to environmental stressors, particularly psychosocial stress and violence." The theory would need to be confirmed in future research.

Looking ahead, the researchers plan to continue investigating what these epigenetic changes mean biologically, as well as study other groups of people and see if the same sites are changed.

Dajani previously published work about how studies like these can shift our perspective on traumatic events.

"We can use this framing to go from victimhood and vulnerability to agency and adaptability," she said. "We can propose that our discovery is proof that humans inherit this adaptability so that they can cope with future unpredictable environments.”

Dajani also recently became a grandmother and reflected on what she would say to her granddaughter about the discovery.

"Even though your grandparents or great-grandparents went through something, you have the tenacity, the 'sumud' [an Arabic word meaning "steadfastness"], to go forward and thrive and flourish," she said.

For Panter-Brick, "it's just pure joy to see the actual results come to fruition at this point.

"And it just means a lot for the population themselves, for our team of women scientists, and for the results of science," she added. "But this is [also] an example of how we can work together for the benefit of humanity by understanding more about the challenges that humans repeatedly find themselves in when they face different kinds of violence."

Editor's note: This story was updated on March 13 to note that the researchers collected cheek swabs, not blood samples as originally stated.

Affected populations: POLG-related diseases are a group of rare, incurable conditions caused by inherited gene mutations. These disease-causing mutations are carried by up to 2% of people of Northern European descent. However, not everyone who carries the mutations ultimately develops a POLG-related disorder.

Estimates suggest that these diseases affect approximately 1 in 10,000 people worldwide.

Causes: POLG-related diseases are caused by several hundred different mutations in the POLG gene. This gene encodes a protein in mitochondria, called DNA polymerase gamma (pol γ), which is needed to replicate and repair the unique DNA found only inside mitochondria, rather than in the cell nucleus.

People develop POLG-related diseases by inheriting either one or two copies of the mutated POLG gene from one or both of their parents.

Mitochondria are the cellular powerhouses responsible for breaking down the carbohydrates and fatty acids in food to produce molecules called ATP, which the body then uses as energy.

Related: Malfunctioning mitochondria may drive Crohn's disease, early study hints

In people with POLG-related diseases, issues with polymerase gamma can either end up decreasing the amount of DNA in mitochondria or introducing mutations into that DNA. And in some cases, both these events can occur.

Ultimately, cells become energy-depleted, and this can lead to organ dysfunction and failure.

POLG mutations are the most common cause of inherited mitochondrial disorders, with around 300 mutations in POLG known to cause disease. Examples of POLG-related diseases include Alpers-Huttenlocher syndrome, ataxia neuropathy spectrum and childhood myocerebrohepatopathy spectrum.

Symptoms: POLG-related diseases can be tricky to diagnose, in part, because they can cause an array of symptoms that vary in severity. These symptoms can also emerge at different times in a person's life, from early childhood to adulthood, depending on which disease they have.

The timing of symptoms partly varies depending on the specific POLG mutation a person carries and the number of copies, as well as the underlying driver of their condition — whether it's mostly related to the loss of DNA or accumulation of mutations.

Once they manifest, the symptoms mostly affect parts of the body that require a lot of energy, such as the central nervous system, muscles and liver.

Common symptoms of POLG-related diseases include progressive weakness of the eye muscles and the muscles that are closest to the center of the body, such as those located in the shoulders or upper arms. People with these diseases may also have droopy eyelids and develop epilepsy and liver failure.

Alpers-Huttenlocher syndrome is one of the most severe forms of POLG-related disease. In addition to the previously listed symptoms, people with this condition also usually experience seizures, a reduced ability to move and liver disease.

People with ataxia neuropathy spectrum, meanwhile experience issues with coordination and balance, as well as reduced nerve function.

Treatments: There is no cure for POLG-related diseases; current treatments instead focus on reducing a patient's symptoms. For instance, doctors can prescribe drugs to help manage seizures or movement difficulties. Transplantation is also an option for patients who experience liver failure.

People with a POLG-related disease typically live for between three months and 12 years after symptoms first begin.

Recent cases: In March 2025, Prince Frederik of Luxembourg, who was second cousin of the heir to the throne, reportedly died of a POLG-related disease at the age of 22. Frederik was the founder and creative director of The POLG Foundation, an organization that supports research into treatments for POLG-related diseases.

We are reviewing the 50mm OLED version, the largest model that has the new display tech. It costs $499.99/£429.99.

There is also a 45mm model in the same style, versions with duller-looking transflective screens but even longer battery life and solar charging. And, new for this year, a more affordable and smaller Instinct E.

Some of our comments will only apply to the Garmin Instinct 3 in its 50mm OLED incarnation, but many stand across the range.

Garmin Instinct 3: Design

• Big and bulky but comfortable to wear 24/7
• May cause skin irritation after prolonged use
• 10ATM water resistance rating

Garmin's Instinct 3 is not a subtle watch. It's for someone not afraid to wear a sports and outdoors watch that professes what it is from across the room.

The experience of wearing it is not at all what you might expect, though. While the Instinct 3 is bulky, it is not remotely heavy thanks to its largely polymer plastic construction. It's just over half the weight of some Fenix 8 watches.

I've worn it overnight throughout testing. And while surely not every Instinct 3 user will want to do this, it's surprisingly easy to get used to.

Garmin has made sure you virtually never need to take the Instinct 3 off, actually. It has 10ATM water resistance, matching the best bar Garmin's dive-specific watches. And as the bezel forms a raised lip above the screen glass, you don't have to be too careful when wearing it.

The materials here are nothing too special — only the shiny orange highlights here are metal (aluminium) and the screen glass is a non-specified "chemically strengthened glass." But Garmin's plastic watches are surprisingly forgiving of rougher treatment.

There’s one other potential issue here. I ended up with a spot of contact dermatitis on my wrist after wearing the Instinct 3 almost 24/7 for several weeks. I haven’t had this with a Garmin watch before, but it is a fairly common issue with wearables like this. It’s the back of the watch body causing the issue, not the strap.

“Some users may experience skin irritation after prolonged use of the watch, especially if the user has sensitive skin or allergies,” warns the Instinct 3 manual.

Garmin Instinct 3: Display

• Crisp, colorful 1.3-inch OLED screen
• No touchscreen (button control only)
• Excellent outdoors visibility

The 50mm Instinct 3 has a 1.3-inch OLED screen. This is every bit as sharp and as clear as that of Garmin's best watches.

You can choose between countless watch faces, sharpness is excellent and outdoors visibility even on a sunny day is good. As with any OLED watch, the screen brightness ramps up in bright conditions.

This naturally uses more battery power, which is why there's still room for the "Solar" versions of this watch. They flip the situation by not only getting clearer in direct sunlight without using additional power, they top up the watch battery using an invisible solar panel.

Which should you pick? If you're not going to be heading out on weeks-long expeditions, don't undervalue OLED's appeal. It gives the watch more personality, a more fluid feel and can fit more stats on-screen clearly.

In the Solar versions, there’s a separate circular area in the screen, which has been a series quirk since the start. Some of the OLED watch’s faces recreate this. Others don’t.

No version of the Garmin Instinct 3 has a touchscreen, though. It's button operation all the way, but that's less of an issue than you might guess. There are few things more annoying than accidentally ending a workout early, which can happen a lot with the touchscreen Garmin Venu 3.

Garmin Instinct 3: Features

• Compass, altimeter and barometer
• No downloadable maps
• Plenty of fitness tracking features

Garmin leans into the outdoors angle of the Instinct 3 in a few obvious ways. Long-press the side button labelled "ABC," for example, and you get quick access to the compass, altimeter and barometer functions. It's a watch suited even to hikers who turn their noses up at an over-reliance on tech.

Up on the top side wall of the watch is a dual-LED flash, which could be a godsend for night (or early morning) activities, or just finding your keys at your front door. There’s a red LED too, which increases visibility without putting out too much light.

One important Garmin favourite feature is missing: maps. You can plan hiking, running and cycling routes on the Garmin Connect app and send them to the Instinct 3. But when you load them, you navigate by a line on a blank background — no indication of streets or terrain.

You need to spend more to get downloadable maps. Check out the Fenix and Forerunner 965 families for that.

The Instinct 3 also lacks music support, but this feels much less of a big issue for potential buyers. It can only control audio played through a connected phone.

Elsewhere, the Instinct 3 gets the usual encyclopaedic array of features in any mid-tier Garmin watch. It also has more enthusiast training stats, like Training Readiness, and unlike the roughly comparable Forerunner 265, has a library of golf features. This includes access to a library of tens of thousands of courses worldwide. And those can be sync'd to the watch.

Garmin Instinct 3: Performance

• Accurate heart rate measurements
• Long battery life
• Reliable dual-band GPS navigation

Most Garmin watches are reliable performers. While the Instinct 3 doesn't have every recent innovation, it does have the ones that suit this series's niche well.

The Instinct 3 has dual-band GPS for example. It's a more battery-sapping mode that can help out in tricky environments like deep valleys, dense forests or skyscraper-packed cities.

We had zero issues with the GPS, and it’s fairly fast to attain signal. As with the Fenix 8, we’ve found last-gen watches were actually faster, but it still takes just a handful of seconds.

The heart rate array doesn't get the same attention. A last-generation Elevate v4 array sits on the back of the watch. This lacks the additional LEDs used to help stabilise readings during exercise. But in our testing it has been mostly exemplary, and in one run recorded using the Instinct 3 and Fenix 8, they came out with exactly the same average and maximum heart rate readings.

Heart rate accuracy is as much dependent on limited (or ideally no) on-wrist movement during exercise, and the Instinct 3’s moulded strap and surprisingly low weight helps here. Last-gen hardware does absolutely rule out the watch ever getting Garmin’s ECG heart reading feature, though, which can be used to monitor for signs of arrhythmia.

The best part of the Instinct 3’s performance is its battery life. We tested it in the most challenging way we could muster, using the watch’s always-on screen mode and tracking plenty of exercise. It lost 49% after four days of solid use, close to Garmin’s claim the watch will last nine days when keeping the clock face active all day. Much longer stamina of “up to 24 days” is possible. But a Garmin Instinct 3 is such a better watch with the always-on mode switched on, you’re not getting the best from this wearable without it.

A 10.5-mile (17 km) tracked run, which took around 90 minutes, took 7% off the battery. This suggests it will last for more than 20 hours of active tracking. Garmin claims 30 hours even when using the more battery-sapping Multi-Band mode.

However, this is largely a reminder of how much the screen has a part to play in real-world battery life. When you’re out for a run on a bright day and use the Instinct 3 to navigate or look at your stats often, its brightness will rise very high.

This watch lasts long enough that you only rarely have to think about how much charge it has, even if your long runs and rides stretch into multi-hour efforts. The Instinct 3 uses Garmin’s classic four-pin connector cable to charge and — one thing Garmin should think about improving one day — charging isn’t super-fast.

After an hour, the Instinct 3 went from 6% to 64%. A full charge takes a while.

Garmin Instinct 3: User reviews

At the time of review, the Garmin Instinct 3 is a little too recent to get a full picture of user reviews just yet. This particular model had an average 3.8 out of 5 score at Amazon.

One reviewer echoed our sentiments about the Instinct 3’s weight. “I'm also surprised that the watch still feels very light on my wrist in regards to the weight,” they said.

The 50mm Solar version had a lower average score of 2.8 out of 5, with some early reviewers criticising the cost and design. One reviewer said it “looks like something that would cost $19.99 at Walmart.”

Should you buy the Garmin Instinct 3?

The Garmin Instinct 3 is an adventuring and outdoors watch that is less intimidating in use than it may appear on a retailer’s website.

It’s a bit bulky, but the low weight keeps it comfy. And the larger size lets Garmin fit in a battery that, for some, can be measured in weeks rather than days.

Those not well-schooled in the Garmin range may be surprised by a couple of the missing features, though. There’s no full mapping in the Instinct 3, even if it’s made for exploring, because that is a feature only available to higher-end watches.

If the Garmin Instinct 3 isn’t for you

Turned off by the Instinct 3’s bulk? Check out the Forerunner 265 and 265S. These are a slightly more mainstream alternative, available in smaller sizes and a less bulky casing. You also get music support, with 8GB of storage for tunes and podcasts.

Want maps? You’ll need to spend more to stay within the Garmin range, the Fenix E or Forerunner 965 being the key models to look out for.

The Coros Pace Pro also brings OLED screen tech and offline maps at a price similar to the Instinct 3. But we find Coros software is less slick, and Garmin’s heart rate accuracy is better.

Garmin Instinct 3: How we tested

The Garmin Instinct 3 was worn for several weeks, almost 24/7, until a skin irritation issue crept in. This is because the watch offers sleep tracking as well as exercise monitoring.

It has primarily been used to track runs, including a marathon-distance run one day, and gym sessions.

Throughout testing the Instinct 3 was predominantly used in its “always on” screen mode. It was also connected to a phone feeding through email and WhatsApp notifications, to provide a more realistic and unflattering evaluation of its battery life.

The symptoms: Patient one was initially admitted to the hospital for respiratory failure after experiencing various symptoms, including a sore throat, difficulty swallowing and extensive weight loss for about six weeks. At the hospital, doctors ordered a computed tomography (CT) scan of the patient's neck, which revealed that he had mucus clogging his upper voice box and right-side vocal cord.

Patient two, meanwhile, was initially hospitalized for having low salt levels in his blood, which caused tissue swelling. His teeth were also in poor condition, which made it harder for him to eat or drink, leading to weight loss, and he had a chronic cough.

What happened next: When he was admitted to hospital, patient one seemed to be wasting away and had signs of bacterial blood poisoning. An additional CT scan, this time of his chest, showed that he had a buildup of fluid in his lungs. Doctors treated him with antibiotics and briefly put him on ventilation to support his breathing. The medical team later identified traces of fungi in the patient's urine and in coughed-up mucus from his respiratory tract.

Related: New cause of asthma lung damage revealed

In the hospital, patient two had a fever of 100 degrees Fahrenheit (38 degrees Celsius). A CT scan revealed multiple lesions in his chest and abdomen. In addition, traces of fungi were detected in his urine.

The diagnosis: Both patients — who were not affiliated in any way but were from the same area — were diagnosed with a rare fungal lung infection called histoplasmosis.

This condition occurs when people inhale spores of a harmful fungus named Histoplasma capsulatum, which usually grows in soil and the poop of birds and bats. Approximately 1 to 2 people per 100,000 in the United States are infected with histoplasmosis each year. However, most people exposed to the fungus don't develop any symptoms. Symptoms are more likely to emerge in people with lung conditions or weakened immune systems, compared to the general population.

In these two cases, the patients' symptoms may have been exacerbated by other diseases that they had before they developed histoplasmosis. For example, patient one had emphysema, a common type of chronic obstructive pulmonary disease (COPD) in which air sacs in the lungs are damaged, which constrains breathing.

The pair also smoked tobacco and cannabis.

The treatment: Following their diagnoses, the patients were prescribed antifungal drugs to combat their infections. However, despite this treatment, both died. Between 5% and 7% of patients who are hospitalized with histoplasmosis die of their infection.

What makes the case unique: Both patients in these cases were already using or planning to use bat poop as fertilizer to grow cannabis for personal use. Patient one had ordered bat poop — or guano — online, while patient two intended to use guano he'd found in his attic following a bat infestation.

In a report describing the cases, doctors noted that various online sources claim that bat guano is a "natural superfood" for cannabis plants because it contains lots of nutrients, such as nitrogen, phosphorus and potassium. Meanwhile, numerous U.S. states have recently legalized the recreational use of cannabis — including Arizona in 2020, New York in 2022 and Ohio in 2023 — which may be encouraging more people to grow their own cannabis, the report authors noted.

The dangers of using bat guano as fertilizer aren't unique to cannabis — the product would be risky for any gardening, the authors emphasized. But given guano is being marketed for cannabis specifically, there is a need to raise public awareness around the potential risks associated with using the poop in this way, they warned.

The Venu 3 is accurate and reliable, and has new-to-Garmin features like ECG heart rate readings. Those who are big-league exercisers should consider a Garmin Forerunner 265 instead, though: it’s a little less glamorous-looking, but has athlete-led features and stats that the Venu series lacks. The Garmin Venu 3’s touch-led approach can also be annoying during workouts, but more on that later.

You’ll pay $449/£449/$749AU for the Venu 3, making it the same price as its predecessor the Venu 2 Plus in the U.S., but slightly more expensive in the U.K.

Garmin Venu 3 review

Garmin Venu 3: Design and display

• Light and comfortable to wear
• Stylish by Garmin standards
• 1.4-inch OLED display

The Garmin Venu 3 combines Garmin’s fitness nous with a design that will appeal to folks who would never strap a Fenix 7 Pro around their wrist. It looks slicker, more like a smartwatch, and there’s less of a sense the wearer is about to start banging on about their marathon times or running club dramas.

You have two size options here, as with many Garmin lines. There’s the 41mm Venu 3S and the 45mm Venu 3, seen here. No matter which size you opt for, you get a silicone strap, Gorilla Glass 3 toughened glass screen protection and a knurled steel bezel, while the rest of the casing is a tough plastic.

It’s fairly light, not too bulky and is generally a joy to wear. However, it’s quite plain-looking as smartwatches go. It’s stylish by Garmin standards, but less so by the standards of the wider industry.

This Venu series also gave Garmin its first-ever OLED watch, back in 2022. The Venu 3 has a super-rich and bright 1.4-inch OLED display with 454 x 454 pixels. It’s great for reading text messages and looks far more lively and vibrant than the transflective display of something like the Garmin Instinct 2.

Just like a smartwatch display, it times out pretty quickly. But there is an “always on” mode that keeps the time on-screen all day, at the expense of battery life. This is a touchscreen and is responsible for the lion’s share of navigation.

Garmin Venu 3: Features

• Limited workout-tracking features
• Takes calls from your wrist
• Features ECG measurements

We used the Garmin Venu 3 for a couple of months, and while we have a lot of affection for this watch, it may not be the right one if you are all about exercise and fitness. Although feature-packed, it lacks quite a few of the features of, say, a Forerunner 965 or Forerunner 265 that we have grown to love.

For example, there are no “suggested workouts” for runners and cyclists. You lose the Performance Condition feature that shows how you’re doing a short way into sessions. And you can’t load routes onto the watch in order to navigate.

The Garmin Venu 3 is a lighter kind of watch. Its special features are things like a speaker and microphone. This combo lets you interact with your phone’s assistant and take calls from your wrist.

At the end of each exercise session, you’ll see your recovery heart rate, which in this case is measured by how many BPM your heart slows down in two minutes, a useful indicator of fitness.

While I have liked the Venu series since it began, it has lost some of its sheen now that OLED screens are pretty common on Garmin watches. The Forerunner 265 has one and costs less, for example, and the smartwatch stuff the Venu 3 can still claim exclusivity on is not one of Garmin’s strongest suits.

Interacting with the digital assistant feels a little clunky and restrictive compared to a smart speaker or Apple Watch. And the touch-led approach has led to me accidentally finishing an exercise session early when taking a quick breather or a quick trip into a shop more times than I can count. This has been the one real annoyance of using the Venu 3.

It is getting ECG readings, though, alongside just a handful of Garmin watches including the Fenix 7 Pro and Epix 2 Pro. This functionality was announced mid-testing, and has now been released in some territories, but is yet to make it to my Garmin Venu 3.

But the message here is only that serious exercise heads may want to consider a Forerunner watch. The Garmin Venu 3 does more than enough to satisfy the vast majority of people on the fitness front.

It has the same slick interface as the Garmin Epix 2, making it a doddle to see your daily stats. The watch has 40 sports modes, and you can get more from the long-standing Garmin ConnectIQ app store if you want.

You can load the Venu 3 up with music, as it has 8GB storage, and play tunes or podcasts on wireless headphones. This feature works well with the touchscreen, and the interface in general feels slick and smooth.

This watch will give you blood oxygenation readings, examine your stress levels and can be used for wireless payments via Garmin Pay. And — a relatively new feature — the Venu 3 now has a Sleep Coach as well as standard sleep tracking. This gives you advice on how to improve your sleep patterns.

Each morning you’ll also see your Morning Report, which is a summary of your sleep and notes for the upcoming day, including the weather. It’s kinda lovely, but if you don’t agree, you can always disable it.

Garmin Venu 3: Performance

The Garmin Venu 3 benefits from all the latest Garmin tech, bar one thing, Multi-Band GPS. This is found in several higher-end Garmin watches these days, including most notably the Forerunner 265, and can really help out in situations when GPS location may be tricky, such as between skyscrapers, in a deep valley or in a very tall and dense forest.

I haven’t had a chance to take the Garmin Venu 3 anywhere quite so exotic, though, and have found its location-tracking performance to be excellent. It’s highly consistent and accurate enough that, for example, you can clearly tell which side of the road you are running on.

It’s the same deal with heart rate readings. The Garmin Venu 3 has the latest generation of the company’s heart rate tech, and it is excellent.

Compared to the Venu 3 Plus, it uses reflector panels and four additional LEDs that only fire up during exercise tracking to improve results. And Garmin’s last-generation heart rate reader hardware was already great.

There are no major accuracy worries here, at least based on our testing — which was primarily running and gym use.

Garmin says you can expect the Venu 3 to last up to two weeks between charges, which is quite a significant step up from the nine days of the Garmin Venu 2 Plus. While that two weeks may be possible, it’s not the kind of longevity you’ll get using the watch to its fullest.

For almost the entire test period I used the Venu 3 with its “always on” screen mode engaged. This meant a simple analog clock face was displayed all day from 7 am to 11 pm when the watch was idle (the style varies depending on the watch face you pick).

It makes the Venu 3 a much better watch, but add the battery drain of a healthy amount of GPS use for exercise tracking and the watch may need charging around every five days. This is one of the drawbacks of an OLED watch — battery life can vary much more than it does in a classic transflective Garmin watch, whose display shows content all the time by design.

However, it’s not as if we’re talking about having to charge your Venu 3 every day, or even every other day.

Should you buy the Garmin Venu 3?

The Garmin Venu 3 is a terrific fitness watch, particularly if you want something a bit glossier and less intimidating-looking than the very outdoors-y Garmin design norm. You get the same interface as the most expensive Garmin watches, displayed through a bright, colorful smartwatch-style OLED screen.

As a Venu watch, though, the Garmin Venu 3 does miss out on some of the more advanced exercise features you get with watches from the Forerunner and Fenix series. Think about whether you want them, as you can now get some of the smartwatch gloss seen here from elsewhere in the Garmin line-up.

If Garmin Venu 3 is not for you

The Garmin Forerunner 265 is the most compelling alternative to the Garmin Venu 3, and the one I’d recommend if you’re big on running or fitness.

With Suggested Workouts, Training Load and on-watch routes (without full mapping) in tow, it comes across as a significantly more serious fitness watch. That said, it doesn’t look as good, and has a smaller screen, no speaker or microphone and no ECG reader. It’s a better watch for some, but definitely not for others.

The Vivoactive 5 is also similar but costs less. It uses aluminum instead of steel, and doesn’t have a speaker or mic, or an altimeter. It uses Garmin’s last-generation heart rate hardware too, but at $299 it is significantly cheaper. It’s a great lower-cost alternative.

Don’t discount the Venu 2 Plus, either. It's a fairly similar watch and may be available for significantly less as an older (but not that old) model. It doesn’t have the Venu 3’s ECG feature, though.

In this adapted excerpt from his book Booster Shots (Penguin Random House, 2025), pediatrician and infectious disease specialist Dr. Adam Ratner looks at a historical measles outbreak in Texarkana, a city at the border of Texas and Arkansas. In the outbreak, the side of the state line people happened to live on determined their fate.

True to its name, Texarkana straddles the border between the states of Texas and Arkansas. In the 1960s, about two-thirds of the population lived in the part of the city that was in Bowie County, Texas, with the remainder residing in Miller County, Arkansas. The division did not generally affect the day-to-day workings of the city, with residents of both counties attending the same local businesses, churches, and events.

However, separate public schools and public health departments were maintained on either side of the state line. Texarkana was a natural laboratory to understand how policy choices could dictate health.

In late June 1970, a 5-year-old Texarkana boy who had traveled out of the area was diagnosed with measles. He represented the first recognized case in an outbreak that would last more than six months and involve more than 600 people, mostly children. That isn't the remarkable part — measles outbreaks were becoming more frequent everywhere.

What made Texarkana different is that State Line Avenue separated two jurisdictions with quite different approaches to measles vaccination. Texas had no requirement for measles vaccination prior to school entry and generally eschewed mass vaccination campaigns.

Fewer than 60% of 1- to 9-year-olds on the Texas side were immune to measles either through vaccination or prior illness. In contrast, Arkansas maintained a school mandate and had held mass immunization campaigns for preschool- and school-aged children in each of the two years prior to the outbreak. An estimated 95% of their 1- to 9-year-olds were immune.

The result was striking. A political division, not a physical one, determined who got measles and who didn't. Of the 633 Texarkana measles cases, 606 (nearly 96% of the total) occurred in people who resided in the Texas portion of the city. This disparity in rates occurred despite significant contact between residents from the two sides. The messages were clear — vaccination had protected children who happened to reside on the Arkansas side of town, and community campaigns and school mandates were highly effective in preventing measles spread.

Related: Measles deaths jumped over 40% from 2021 to 2022, CDC reports

The Texarkana story is frequently cited in public health circles and is used as a teaching case for students of epidemiology. The lesson that is sometimes missed is that in addition to showing that vaccination protects against disease, the Texarkana measles outbreak also provides a stark reminder that political decisions about funding for public health, acceptability of school mandates, and myriad other issues can have real and lasting effects on the health of populations.

Today, Texarkana's unusual geographic and political arrangement continues to instruct us about the deeply intertwined nature of politics and health. Under the Patient Protection and Affordable Care Act (ACA, also known as Obamacare), which was passed in 2010, states were required to expand Medicaid coverage to nearly all adults with incomes up to 138 percent of the federal poverty level, with coverage going into effect in 2014.

A 2012 Supreme Court decision (National Federation of Independent Business v. Sebelius) made states' acceptance of the ACA's Medicaid expansion funds optional rather than mandatory. Arkansas accepted Medicaid expansion; Texas did not. Jonathan M. Metzl, author of "Dying of Whiteness," has chronicled how states' political decisions, including accepting or refusing Medicaid expansion, can change the health — and even alter the life expectancy — of its citizens. It is hard to imagine a place where that line is so sharply drawn as in Texarkana.

A 2023 report from Public Health Watch [a nonprofit news organization] detailed a "widening divide in health care access" between the two sides of Texarkana on the basis of those decisions. Despite the demographic similarities between the Texas and Arkansas sides of the city, after nine years of Medicaid expansion, the differences were stark. More non-elderly adults uninsured, more hospitalizations for life-threatening conditions such as diabetic ketoacidosis, worse access to care — these are the legacy of Texas's refusal to accept the ACA's Medicaid expansion.

Just as the 1970 measles outbreak made clear, in Texarkana, living on the wrong side of State Line Avenue can be hazardous to your health.

From "Booster Shots", by Adam Ratner, MD, MPH, published on February 11, 2025, by Avery, an imprint of Penguin Publishing Group, a division of Penguin Random House LLC. Copyright © 2025 by Adam Ratner, MD, MPH.

These genetic variants were likely inherited from humans' extinct cousins, the Neanderthals, tens of thousands of years ago, according to a study published Mar. 10 in the journal PNAS. And it may be that the variants offered an evolutionary advantage by helping early hunter-gatherers thwart infections, new data suggest.

In some people of European or African descent, the lactase gene helps carriers digest a sugar called lactose in milk after they're weaned off of breast milk; this phenomenon is known as "lactase persistence." Many people who carry alternative versions of the gene can't continue breaking down lactose after infancy, so they become lactose intolerant.

The versions of the lactase gene behind lactase persistence are believed to have emerged in populations in Europe and Africa between 5,000 and 10,000 years ago, around the same time humans on these continents began rearing animals and consuming their milk.

Related: Papua New Guineans, genetically isolated for 50,000 years, carry Denisovan genes that help their immune system, study suggests

This has led scientists to theorize that the lactose-tolerance variants were selected for within these populations, meaning they became more common over the course of evolution because they offered an advantage. In this case, they may have increased survival rates by allowing adults to absorb nutrients from milk.

However, until now, little was known about the genetic mechanisms behind lactase persistence and lactose intolerance in East Asians. About 65% of adults worldwide are thought to be lactose intolerant, but this figure rises to between 70% and 100% in East Asian populations.

In the new study, scientists compared thousands of genomes sampled from modern humans, including those with East Asian, European or African ancestry. The data came from individuals in a range of countries, such as China, Japan, Spain, Italy and Nigeria.

The analysis revealed that around 25% of the people with East Asian ancestry carried versions of the lactase gene that are not found within the European or African populations. That's around the same proportion of people who have lactase persistence in East Asian populations. These genetic variants trigger an increase in the activity of the lactase gene in the body, the researchers found.

At first glance, this suggests that these genetic variants may have also been selected for during evolution for dietary reasons, the researchers said. However, further analyses in the same study revealed that this may not have been the case.

Indeed, the researchers went on to compare samples of East Asian genomes with the genome of a Neanderthal who lived in the Altai Mountains in Siberia around 120,000 years ago. This led them to discover that the East Asian variants of the lactase gene were likely inherited by hunter-gatherers from Neanderthals as a result of interbreeding events between the two groups.

Neanderthals and Homo sapiens are known to have interbred on multiple occasions over the millennia. This happened after both species came into contact with one another following the migration of the latter group out of Africa into Eurasia, possibly up to 250,000 years ago.

The new results suggest that the lactose-intolerance variants started being selected for between 25,000 and 28,000 years ago — more than 10,000 years before dairy culture emerged in the Altai Mountain region.

In other words, the variants emerged before people in the region started regularly consuming milk. This suggests that the selective pressure on these variants was not related to improving people's ability to digest lactose.

To figure out what other advantages these variants might offer, the team scoured a database chronicling gene activity in different cells. They discovered that the lactase gene variants seen in East Asian people altered the activity of three genes in immune cells, causing them to expand in number.

Based on this result, the study authors think it's possible that these variants were selected for because they somehow enhanced the ability of East Asian hunter-gatherers to combat infections.

"Neanderthals — having inhabited Eurasia for approximately 400,000 years — likely carried alleles [genetic variants] adapted to local pathogens and environmental challenges," study co-author Shuhua Xu, a professor of human population genetics at Fudan University in China, told Live Science in an email.

Taken together, the findings imply that variants of the lactase gene may have been selected for different reasons across the world, the researchers concluded. These findings may prompt scientists to question why selection of the lactase gene occurred in European and African populations, they added; perhaps the answer isn't solely about drinking milk.

Mobvoi has just released its first-ever adventure watch, the TicWatch Atlas and its specs are impressive — even more so when you factor in the price. This smartwatch costs just $349, but it has a body made of reinforced stainless steel and a tough Sapphire Crystal on its display, and its durability has been certified to military standards. It can last up to 45 days on a single charge in Essential mode and comes with GPS, compass, barometer and over 100 activity modes. Plus, it is relatively light and easy on the eye. The TicWatch Atlas could, in fact, be one of the best budget fitness trackers to buy in 2025.

There is a caveat — the TicWatch Atlas runs on Google Wear OS, so it is not compatible with Apple devices. Those who want seamless integration with their iPhones may need to invest in another fitness tracker instead.

TicWatch Atlas smartwatch review

TicWatch Atlas: Design

• Comfortable to wear 24/7
• Military-grade durability
• Controlled by a side button and a crown

The TicWatch Atlas is a tough cookie. Its body is made of stainless steel, reinforced nylon and 7000-series aluminum — a premium-quality material often used in the aviation industry due to its high durability and resistance to corrosion. This smartwatch also has a 5ATM waterproof rating for open-water swims, and it is certified to the MIL-STD-810H military standard. This means it has been tested against harsh environmental conditions, including high temperatures, solar radiation, rapid changes in air pressure and physical impacts. And as we mentioned before, the display in Atlas is covered with scratch-resistant Sapphire Crystal glass.

Indeed, our TicWatch Atlas displayed good durability in our tests. We wore the watch for nearly two months, exposing it to rain, cold January temperatures and intense workouts, and it looked just as good, and worked just as well, at the end of our testing as it did in the beginning — and we are not particularly gentle with our fitness trackers!

Given how rugged it is, the TicWatch Atlas is surprisingly comfortable to wear. It weighs just 1.66 oz (47.2 g) without a band, and while you could argue that there is still a lot of machinery to carry around on the wrist, this model is still lighter than many of its mainstream competitors. For example, the stainless steel version of the Garmin Fenix 8 weighs nearly 2.08 oz (59 g) without a band. We also liked the silicone straps. They were soft, comfortable on the skin and stayed in place during exercises.

The TicWatch Atlas is controlled with a touchscreen, a button on the right side and a crown around the display. We liked that approach. A mixture of physical and touch controls makes this watch easy to navigate, especially during hikes and cardio workouts when it is not always convenient to fiddle with a fitness tracker for too long.

TicWatch Atlas: Display

• Colorful 1.43-inch (3.6 cm) AMOLED display
• Two-tone format in Ultra-low-power mode
• The screen gets smudged easily

The TicWatch Atlas features a colorful 1.43-inch (3.6 cm) AMOLED display that is bright and easy to read. It is also widely customizable. There are a host of pre-loaded watch faces to choose from, and thousands more are available on Google Play. This wide personalization reminds us of the Samsung Galaxy Watch 6 — a bonus point for those who like their display to match their style.

In the Ultra-low-power mode, the display is reduced to a two-tone format and only shows a handful of essential metrics, such as date, time, steps, heart rate and battery life (this also applies to the Always On screen.) However, this limited functionality does not interrupt workout tracking. When your TicWatch is in this power-saving mode, the screen will change colors slightly to indicate which heart rate zone you are in during a workout, meaning you can still gauge your exercise intensity at a glance. It is worth noting that the TicWatch Atlas can last up to 45 days on a single charge when used in this battery-saving mode — and such longevity is not something we see often in smartwatches, premium or not.

Our TicWatch Atlas seemed to attract a lot of dust and smudges during testing. While it was not a huge deal for us (we could still easily read the screen, even when it had our fingerprints all over the place), it is something to consider if you like your watches to stay pristine.

TicWatch Atlas: Features

• Plenty of fitness-tracking features
• GPS, compass, altimeter and barometer
• Fall detection and other emergency features

The TicWatch Atlas offers a wide range of fitness-tracking features, from continuous heart rate monitoring and recovery time assessments to timers, stopwatches and over 100 activity modes. It works as a sleep tracker, too, thanks to its in-depth measurements of sleep quality, respiratory rate, skin temperature and other vital metrics.

All health stats and workout logs are stored in the Mobvoi Health app, so you can track your progress over time. The app is free and easy to use.

The TicWatch Atlas has a significant number of features to aid outdoor activities, including GPS navigation, a compass and a barometer to track changes in altitude. It is also equipped with emergency features, such as SOS calls from your wrist (you can do that by pressing the rotating crown five times.) Mind you, these emergency features can be quite sensitive. On one occasion, we accidentally triggered an SOS call with our weightlifting gloves, resulting in a somewhat awkward conversation with the first responders. However, you can disable these features in the watch settings.

The TicWatch Atlas runs on the Google Wear OS and this means one thing — easy access to Google's apps. For example, you can get email notifications, pay for your shopping with Google Wallet, play YouTube music or download apps on Google Play. The TicWatch Atlas is a smartwatch in the full sense of the word.

TicWatch Atlas: Performance

• Good battery life and fast charging
• Accurate health-tracking features
• Good movement detection

Performance-wise, the TicWatch Atlas is a solid piece of kit. We liked its long battery life, ultra-fast charging and largely accurate tracking features, and we did not experience any issues with app connectivity or processor performance. Sure, it may not be as snappy and robust as some of the top-shelf Garmin watches, for example, but it still punches way above its affordable price point.

To start with, it took us on average 30 minutes to hit 100% battery on our TicWatch Atlas. Our watch would typically last four to five days in normal use, with Always-On enabled and hour-long workouts on most days of the week. When we tweaked the battery settings to reduce power use, our Atlas lasted nearly two weeks. We did not have a chance to test the Ultra-low-power use to see if the 45-day claim is valid, but by the looks of it, this smartwatch seems capable of doing so.

The TicWatch Atlas was also relatively easy to use, even though the navigation took us a few days to get used to. The watch did not seem to lag during intensive tasks or switch functions by accident. Also, all metrics and health stats were presented with a good level of detail, but in a clear and easy-to-understand way. However, the TicWatch Atlas does not offer much in terms of personalized fitness coaching, so it is mostly up to the user to interpret their health data. For beginners, this may be a huge downside.

Most importantly, the TicWatch Atlas displayed some great accuracy in our tests. Its step counter and GPS navigation were largely reliable, giving us a good indication of the distance covered, and its workout modes proved to be useful for tracking our training sessions and hikes outdoors. We were also impressed with its heart rate measurements.

During one workout, we wore the TicWatch Atlas alongside a Polar H9 chest-strap heart rate monitor to compare the obtained data. Our watch did a very good job of picking up on the heart rate during rest and low-to-moderate intensity exercises, and its accuracy only slightly tailed off with intense to very intense cardiovascular activity. While these heart rate readings are not 100% accurate, they still place the TicWatch Atlas on par with many of its pricier mainstream counterparts.

TicWatch Atlas: User reviews

Amazon's customer reviews place the TicWatch Atlas at a solid 4.6 out of 5 stars rating. This smartwatch was typically praised for its durable design, battery life, vibrant display and extensive tracking features. As one user said, "I'm a sailor and I spend a lot of time outside, on the boat. Handling lines and just generally knocking about on a boat can be pretty rough on watches. I've had cracked displays and damage to past smartwatches due to the rough handling. That's why, when the Ticwatch Atlas came out, I jumped on it. After three weeks, I don't regret my decision a bit! Not only is the Atlas tough, but it retains that amazing battery life and easy-to-read two-level display of past TicWatches. [...] Highly recommended."

Negative reviews, though few and far between, tended to revolve around individual faulty units and patchy app connectivity, but a few users also complained about its "terrible interface." As one review summed it up, "TicWatch is a great idea but just not there yet."

Should you buy the TicWatch Atlas?

✅ Buy it if: You want a formidable smartwatch, but at an affordable price. The TicWatch Atlas offers a serious alternative to pricey Garmin watches and other mainstream options with its military-grade durability, robust fitness-tracking features and great performance. It is very comfortable to wear, looks great and can last weeks on a single charge. There is hardly anything to fault with this watch.

❌ Do not buy it if: You are an iOS user, or if you are looking for a more basic fitness tracker. TicWatch Atlas is designed with outdoor enthusiasts in mind, so for those who are only occasional exercisers or gym-dwellers, this excellent smartwatch may be overkill. Also, it does not have any advanced coaching features that would benefit fitness beginners.

If TicWatch Atlas is not for you

The Coros Apex 2 is a great alternative to the TicWatch Atlas. Both of these smartwatches offer advanced tracking features, sturdy design and customizable displays, and they both cost around $349.

If you want an outdoor watch with all the bells and whistles imaginable (and do not mind spending some serious money), the Garmin Fenix 8 may be more up your street. This formidable GPS watch does it all, from beastly performance and excellent design to impressive specifications. Plus, it is one of the very few fitness trackers you can wear while scuba diving.

The Garmin Fenix 8 is still a relatively new model, which is why it costs at least $1,000. If you are looking for something cheaper but of similar quality, you may want to consider its older sibling. The Garmin Fenix 7 may not be as efficient and waterproof, but it delivers a broadly similar experience to the Fenix 8 for just under $650.

TicWatch Atlas: How we tested

We spent nearly two months trying and testing the TicWatch Atlas smartwatch, looking at its design, features, tracking performance, battery life, app connectivity and ease of use. We wore it during the day while sleeping and when doing a range of workouts, from leisurely hikes to high-intensity indoor rowing and weightlifting in the gym. Finally, we assessed the accuracy of our TicWatch Atlas by comparing its heart rate measurements with the data we obtained using a Polar H9 chest-strap heart rate monitor.

Now, new research fills in one piece of the puzzle: Metformin triggers the body to expel glucose from the bloodstream into the intestines, where bacteria feed on the carbohydrate to make compounds that may help control blood sugar levels.

In the new study, published March 3 in the journal Communications Medicine, researchers calculated that metformin treatment increased how much glucose was released into the gut nearly fourfold. That seemed to boost the production of fatty compounds that help protect the gut and reduce inflammation.

Multiple pathways

Most research has focused on metformin's effects in the liver, where it boosts how cells respond to insulin and blocks the synthesis of the sugar glucose. But some studies have suggested that the drug also acts on the gut, perhaps by blocking glucose uptake into the bloodstream.

"Many people are working on the gut action of metformin because if you take metformin orally, the intestines are exposed to very high concentrations," said senior study author Dr. Wataru Ogawa, a medical researcher at Kobe University in Japan. (Ogawa received research support and lecture fees from the metformin manufacturer Sumitomo Pharma.)

Previously, Ogawa's team showed that the body excretes glucose into the hollow tunnel of the human gut where food and waste travel, known as the lumen. This happens in people with and without diabetes. "It means that this is a physiological function that humans have," Ogawa told Live Science.

Related: Ozempic-style drugs tied to more than 60 health benefits and risks in biggest study-of-its-kind

Feeding gut bacteria

In the new study, the researchers found that metformin nearly quadrupled the rate of glucose excretion into the gut in five people with type 2 diabetes, and they replicated those findings in mice.

Keeping glucose out of circulation by directing it to the gut might directly lower blood sugar levels, but scientists told Live Science they think this explains only part of metformin’s therapeutic effects.

Nicola Morrice, a metformin researcher at the University of Dundee in Scotland who was not involved in the study, told Live Science in an email, "I do not expect this to be the drug's main mechanism of action."

Besides drawing sugar out of the bloodstream, excreted glucose could also have an indirect effect on blood sugar by feeding gut bacteria, other experts told Live Science.

Dr. José-Manuel Fernández-Real, a medical researcher at the University of Girona in Spain who was not involved in the study, told Live Science in an email, "Some bacteria, particularly those that thrive on simple sugars, may experience increased growth, while others that rely on complex carbohydrates or fiber fermentation might be less affected."

A glucose molecule has a backbone of six carbon atoms, so to determine the rate at which gut bacteria break down glucose into other molecules, Ogawa had to find a way to keep track of these carbons. His team injected mice with glucose containing a "heavy" isotope, meaning a version of carbon that carries an extra neutron. This allowed them to trace the heavy carbons as the bacteria transformed glucose into other compounds.

Stool samples revealed that bacteria in mice treated with metformin had converted the heavy glucose into short chain fatty acids (SCFAs). "Bacterial species that produce short chain fatty acids are generally 'good' bacteria," suggesting metformin’s effects could potentially foster a healthy microbiome, Ogawa said.

Metformin treatment caused SCFAs containing heavy carbon to increase by just 1% in stool samples. However, Manuel Vázquez-Carrera, a pharmacology researcher at the University of Barcelona who was not involved with the study, told Live Science in an email that "most SCFAs are rapidly absorbed and utilized rather than excreted." That means the measurement was likely an underestimate.

And "even a slight rise in SCFA production could enhance gut barrier function, reduce inflammation, and improve insulin sensitivity, all of which are beneficial for managing diabetes," Fernández-Real speculated.

The study had a few limitations. First, the researchers did not assess how higher levels of gut SCFAs affected the health of the mice. It also included "a very small number of participants who were receiving varying doses of metformin as part of their treatment regimes," Morrice said.

The mouse work also involved only male rodents, so possible sex differences in the drug's actions were not explored. Beyond testing metformin's effects on five diabetes patients, Ogawa said he has finished a larger, gold-standard trial in humans to further study the drug's impacts on the gut. The researchers haven't completed the analysis, but as of yet, they haven't seen any sex differences.

Morrice suggested that future work could explore how metformin affects glucose excretion in mice that consume different diets, such as high-fat, high-sugar diets, which are linked to obesity.

So what does it mean for cancer to be in remission, and what does it mean to have been cured?

First, it's important to note that there are two types of cancer remission: "complete remission" and "partial remission." Complete remission means that a person's cancer is responding to treatment, that they have no signs or symptoms of the disease, and there are no cancerous cells in their body that can be detected by a scan or a blood test, for instance.

Partial remission means that treatment is working but that tests show some cancerous cells remain in the body. In contrast, when a patient has "stable disease," it means their condition is neither improving nor worsening in response to treatment.

Doctors can't predict how long remission will last, so there's a chance the cancer could come back. Remission can last weeks or years.

Related: What are cancer vaccines?

If a patient remains in complete remission for five years or more, then some doctors may say the patient is "cured," which means they've shown a long-term absence of symptoms or signs of cancer.

However, even if a patient is considered cured, they may still have undetected cancer cells lurking in their body that may cause a recurrence of the disease one day. Doctors may be more likely to say that a patient is "cured" if they have a type of cancer that has a high five-year cancer survival rate when detected early, such as breast cancer or melanoma, which is a type of skin cancer.

Epidemiologists may also use a term known as "statistical cure" in this context. This means that a patient survives long enough that their risk of death from cancer returns to that of the general public, Dr. Vijay Trisal, a surgical oncologist at the City of Hope cancer research center in California, told Live Science.

For instance, if someone had colon cancer 10 years ago and now they are free of the cancer, their risk of dying from the disease has effectively gone back to the baseline risk that would be expected of other people their age, he added.

Nevertheless, the term "cure" should be used with caution, Trisal said. Although it may alleviate some patients' anxiety and allow them to resume their normal lives, it can make others less vigilant and more likely to avoid future tests and screening that could help detect reoccurrence, he added.

A study my colleagues and I conducted of over 3,000 people with autoimmune disease uncovered many extra long-lasting disadvantages when the misdiagnosis involved a mental health or psychosomatic label (often termed an "in your head" misdiagnosis by patients).

These often included feelings of shame, self-doubt and depression. For some, it extended to suicidal thoughts and even suicide attempts.

A further consequence was that people had much lower trust in doctors. This distrust led to some people avoiding seeking further medical help, often for fear of being disbelieved again.

A concerning finding from our study was that these negative emotions and distrust often remained just as strong many years after feeling that a doctor had not believed their symptoms.

Psychological scars were deep and usually unhealed. Over 70% of people reporting a psychosomatic or mental misdiagnosis said that it still upset them. And over 80% said that it had damaged their self-worth.

One of our study participants, who had several autoimmune diseases, told her story that spoke for many: "One doctor told me I was making myself feel pain — I still can't forget those words. Telling me I'm doing it to myself has made me very anxious and depressed."

Related: It's not 'all in your head' — neurologist Suzanne O'Sullivan on psychosomatic illness

'I still can't forget these words'

These findings were not just anecdotal. Overall, we found depression levels were significantly higher and wellbeing levels lower in people who reported receiving mental health or psychosomatic misdiagnoses.

We chose to use this woman's testimony in the title of our study: "I still can't forget those words." Not only did it accurately reflect our findings, but it symbolises our research team's ethos to give these often unheard patients a voice.

The hurt of misdiagnosis was compounded by having "nowhere to voice my anger" or distress. Some of the most moving stories were from people whose early symptoms of autoimmune disease, when they were still children, had been disbelieved by doctors.

Even in middle or older age, those words and feelings had remained with them for decades, often felt as strongly as the day that they were heard. As one of the patient partners in our research team described it, they lived the rest of their lives with "seared souls."

A woman with lupus told the interviewer that her doctor had told her at age 16 that she had "too many symptoms for it not to be hypochondria." She spoke very emotively and articulately about the damage caused to a developing sense of self.

It has affected my mental health very negatively and I do think it's affected me in my like sense of self. It's not good for anyone at any age but as a teenage girl being told you don't know your own feelings is absolutely no way to shape a human being.

It is natural when hearing all these very difficult stories, and seeing the damage caused, to blame doctors, but is that fair? Doctors very rarely set out to cause harm. Rather, in some cases, it is impossible to diagnose autoimmune diseases quickly.

However, our study highlights that some doctors do reach too quickly for a psychosomatic or mental health explanation for autoimmune disease symptoms.

Some research that may have influenced doctors in giving psychosomatic misdiagnoses says that a long list of symptoms is a red flag that the symptoms are not caused by a disease. This generalisation rather dangerously fails to account for the fact that a long list of symptoms is also a red flag for many autoimmune diseases.

Many autoimmune symptoms are also invisible, and there are no clear tests that will show how bad they are to the doctor. Some of the terms that patients find upsetting and dismissive when doctors talk or write about their symptoms include "vague" and "non-specific."

Doctors often write letters quickly due to health service constraints, sometimes unthinkingly using terms passed down from their seniors; letters that use terms like "patient claims" or "no objective evidence found of" can increase feelings of being disbelieved.

Empathetic listening

Our research suggests that more doctors need to think about autoimmunity as a diagnosis early on when faced with multiple varied symptoms that often don't seem to fit together. Above all, many diagnostic clues can be found by listening to and believing the people experiencing the symptoms.

Empathetic listening and support are also required to help misdiagnosed patients heal emotionally — they very rarely can just "move on" as one doctor advised. We should not underestimate the power of doctors saying "I believe you" to patients with multiple invisible symptoms, and "I am sorry for what has happened in the past" if they had a difficult road to diagnosis.

Most of the 50 doctors interviewed for the study reported that misdiagnoses were common in autoimmunity, but few had realised that the repercussions of these misdiagnoses were so severe and long lasting.

Reassuringly, almost all of them were saddened and motivated to improve their patients' experiences. Several explained that they thought they were being reassuring by telling patients that their symptoms were most likely to be psychological or stress-related and thought this would be preferable to patients worrying about having a disease.

Although many people experience mental health and psychosomatic symptoms, and doctors must consider them as a possible explanation, a clear lesson from our study is that psychosomatic (mis)diagnoses are rarely seen as reassuring to patients with autoimmune disease symptoms. Rather, they are usually deeply damaging with lifelong and life-changing repercussions.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.