We all want to 'age successfully' with as few health issues as possible. A new study suggests getting more than seven hours of sleep a night could go a long way to achieving that goal.

The study involved 3,306 participants aged 45 and over, whose sleep habits were recorded in 2011, 2013, and 2015, followed by a health check five years later. The data, analyzed by a team from Wenzhou Medical University in China, showed that those who bank at least seven hours of sleep a night tend to have significantly better health later in life.

"Successful aging was evaluated in 2020 and was defined as being free of major chronic diseases, no physical impairment, high cognitive function, good mental health, and active engagement with life," write the researchers in their published paper.

By the end of the study period, only 455 individuals (13.8 percent) checked all of the successful aging criteria boxes. Of those, 307 (around two thirds) were consistently getting more than seven hours of sleep a night.

The participants were split into five groups based on their sleeping habits across the four years: long stable (8-9 hours of sleep regularly), normal stable (7-8 hours regularly), decreasing (from an average of over 8 to fewer than 6), increasing (from an average of fewer than 6 to over 8), and short stable (5-6 hours regularly).

Chances of successful aging was significantly greater among the long stable and normal stable groups (17.1 percent and 18.1 percent respectively) compared to those in the decreasing (9.9 percent), increasing (10.6 percent), and short stable (8.8 percent) groups.

"Relative to participants with the normal stable sleep duration trajectory, those with the low stable and increasing trajectory had 36 percent and 52 percent lower odds of successful aging, respectively," write the researchers.

"Participants with decreasing trajectories also exhibited lower odds, though this was not statistically significant, likely due to sample size limitations."

The team accounted for factors including weight, alcohol consumption, and sex in their analysis, though the nature of the study can't confirm a direct cause-and-effect link.

What it does offer is more evidence of the importance of consistent, extended sleep.

Previous research has also highlighted seven hours a night as a potential sweet spot for sleep and aging well. We also know there are links between sleep and protection against a wide range of physical and mental health issues.

China, where the research was carried out, has one of the fastest aging populations on the planet – but it's very much a global issue. As the world gets older, we need to ensure it stays healthy as well.

"These findings underscore that chronic sleep deprivation, as well as the patterns of increasing and decreasing sleep duration, are not mere age-related changes," write the researchers.

"Rather, they emerge as pivotal indicators of obstacles in the pursuit of successful aging."

The research has been published in BMC Public Health.

Just five minutes of exercise a day could be enough to noticeably shift blood pressure in a downward direction, new research has found.

High blood pressure is classified as having a reading of 140 millimeters of mercury (mmHg) or higher when blood is being pumped through the arteries – known as systolic pressure – and 90 mmHg or greater when the heart is diastolic, or at rest.

Just a few minutes of activity that gets your heart rate up, such as cycling or climbing stairs, was estimated to lower systolic blood pressure by 0.68 mmHg and diastolic blood pressure by 0.54 mmHg, the data showed.

Also known as hypertension, the condition carries an increased risk of serious health problems, including heart attacks and kidney damage.

"The good news is that whatever your physical ability, it doesn't take long to have a positive effect on blood pressure," says first author and epidemiologist Jo Blodgett from University College London.

"What's unique about our exercise variable is that it includes all exercise-like activities, from climbing the stairs to a short cycling errand, many of which can be integrated into daily routines."

The study was based on a week of activity data and blood pressure readings collected using wearable devices on 14,761 participants.

Daily activity was split into six types: sleep, sedentary behavior, slow walking, fast walking, standing, and vigorous exercise. These daily patterns were then referenced against blood pressure, with several other potential influences (including age and sex) factored in.

The researchers then calculated some 'what if' scenarios – how changing those habits could change blood pressure. For example, a 2 mmHg improvement in SBP was estimated if exercise replaced 21 minutes of sedentary time or 21 minutes of fast walking a day.

"For those who don't do a lot of exercise, walking did still have some positive benefits for blood pressure," says Blodgett. "But if you want to change your blood pressure, putting more demand on the cardiovascular system through exercise will have the greatest effect."

As an observational study involving multiple variables, no direct causal link can be drawn. Nevertheless, as the team analyzed data from a large group of people, there's a strong indication that just a small amount of exercise could affect blood pressure (which other studies have suggested too).

Given the relatively small amount of time needed, and the variety of straightforward exercises that make a difference, the international team behind the research hopes these findings can help the 1.28 billion adults worldwide with hypertension.

"The finding that doing as little as five extra minutes of exercise per day could be associated with measurably lower blood pressure readings emphasizes how powerful short bouts of higher intensity movement could be for blood pressure management," says joint senior author Emmanuel Stamatakis, a professor of physical activity and population health at the University of Sydney.

The research has been published in Circulation.

But as a new study by researchers from the Chinese Academy of Sciences and Reichman University in Israel warns, artificial intelligence may also be inadvertently imitating another, less noble hallmark of modern humanity: trashing the environment.

Fueled by the surging popularity of generative AI systems that include chatbots like ChatGPT and other content-creation systems, we could end up with between 1.2 million and 5 million metric tons of additional electronic waste by the end of this decade.

The new study focuses particularly on large language models (LLMs), a type of AI program that can interpret and produce human language, along with performing related tasks.

Trained on vast datasets of text, LLMs identify statistical relationships underlying the rules and patterns of language and apply them to generate similar content, enabling uncanny capabilities like answering questions, producing images, or writing text.

In addition to its many benefits, however, generative AI has raised a host of philosophical and practical questions for society – from concerns about AI taking our jobs to fears of it being misused by humans, deceiving us, or even becoming self-aware and rebellious.

And as the new study highlights, generative AI is also beginning to raise alarms about the daunting amount of extra e-waste the technology is expected to indirectly generate.

Generative AI is reliant on prompt technological improvements, including to hardware infrastructure as well as to chips. The upgrades needed to keep pace with the technology's growth could compound existing e-waste issues, they note, depending on the implementation of waste-reduction measures.

"LLMs demand considerable computational resources for training and inference, which require extensive computing hardware and infrastructure," the study's authors write. "This necessity raises critical sustainability issues, including the energy consumption and carbon footprint associated with these operations."

Previous research has largely focused on the energy use and associated carbon emissions from AI models, the researchers note, paying relatively little attention to the physical materials involved in the models' life cycle, or the waste stream of electronic equipment left in their wake.

Led by Peng Wang, an expert in resource management with the Chinese Academy of Sciences' Key Lab of Urban Environment and Health, the study's authors calculated a forecast of possible e-waste quantities created by generative AI between 2020 and 2030.

The researchers envisioned four scenarios, each with a different degree of production and use of generative AI systems, from an aggressive, widespread-use scenario to a conservative, more constrained scenario.

Under the more aggressive scenario, total e-waste creation due to generative AI could grow as high as 5 million metric tons between 2023 and 2030, with annual e-waste potentially reaching 2.5 million metric tons by decade's end. That's more or less the equivalent of every person on the planet discarding a smart phone.

The high-usage scenario also forecast that AI's extra e-waste would include 1.5 million metric tons of printed circuit boards and 500,000 metric tons of batteries, which can contain hazardous materials like lead, mercury, and chromium.

Just last year, a mere 2.6 thousand tons of electronics was discarded from AI-devoted technology. Considering the total amount of e-waste from technology in general is expected to rise by around a third to a whopping 82 million tonnes by 2030, it's clear AI is compounding an already serious problem.

By examining these different scenarios, Peng and his colleagues draw attention to an important point: Generative AI doesn't necessarily have to impose such an excessive e-waste burden.

The researchers note the International Energy Agency and many tech companies advocate for circular economy strategies to address e-waste.

According to the new study, the most effective strategies are lifespan extension and model reuse, which entail extending the longevity of existing infrastructure and reusing key materials and modules in the remanufacturing process.

Implementing circular economy strategies like these could reduce the e-waste burden from generative AI by up to 86 percent, the researchers report.

The study was published in Nature Computational Science.

We finally know what brought light to the dark and formless void of the early Universe.

According to data from the Hubble and James Webb Space Telescopes, the origins of the free-flying photons in the early cosmic dawn were small dwarf galaxies that flared to life, clearing the fog of murky hydrogen that filled intergalactic space. A new paper about the research was published in February.

"This discovery unveils the crucial role played by ultra-faint galaxies in the early Universe's evolution," said astrophysicist Iryna Chemerynska of the Institut d'Astrophysique de Paris.

"They produce ionizing photons that transform neutral hydrogen into ionized plasma during cosmic reionization. It highlights the importance of understanding low-mass galaxies in shaping the Universe's history."

At the beginning of the Universe, within minutes of the Big Bang, space was filled with a hot, dense fog of ionized plasma. What little light there was wouldn't have penetrated this fog; photons would simply have scattered off the free electrons floating around, effectively making the Universe dark.

As the Universe cooled, after about 300,000 years, protons and electrons began to come together to form neutral hydrogen (and a little bit of helium) gas.

Most wavelengths of light could penetrate this neutral medium, but there was very little in the way of light sources to produce it. But from this hydrogen and helium, the first stars were born.

Those first stars delivered radiation that was strong enough to peel electrons away from their nuclei and reionize the gas. By this point, however, the Universe had expanded so much that the gas was diffuse, and could not prevent light from shining out.

By about 1 billion years after the Big Bang, the end of the period known as the cosmic dawn, the Universe was entirely reionized. Ta-da! The lights were on.

But because there's so much murk in the cosmic dawn, and because it's so dim and far away across time and space, we've had trouble seeing what's there.

Scientists thought that the sources responsible for most of the clearing must have been powerful – huge black holes whose accretion produces blazing light, for example, and large galaxies in the throes of star formation (baby stars produce a lot of UV light).

JWST was designed, in part, to peer into the cosmic dawn and try to see what lurks therein. It's been very successful, revealing all sorts of surprises about this crucial time in the formation of our Universe. Surprisingly, the telescope's observations now suggest that dwarf galaxies are the key player in reionization.

An international team led by astrophysicist Hakim Atek of the Institut d'Astrophysique de Paris turned to JWST data on a galaxy cluster called Abell 2744, backed up by data from Hubble.

Abell 2744 is so dense that space-time warps around it, forming a cosmic lens; any distant light traveling to us through that space-time becomes magnified. This allowed the researchers to see tiny dwarf galaxies close to the cosmic dawn.

Then, they used JWST to obtain detailed spectra of these tiny galaxies. Their analysis revealed that, not only are these dwarf galaxies the most abundant galaxy type in the early Universe, they are far brighter than expected.

In fact, the team's research shows that dwarf galaxies outnumber large galaxies by 100 to 1, and their collective output is four times the ionizing radiation usually assumed for larger galaxies.

"These cosmic powerhouses collectively emit more than enough energy to get the job done," Atek said.

"Despite their tiny size, these low-mass galaxies are prolific producers of energetic radiation, and their abundance during this period is so substantial that their collective influence can transform the entire state of the Universe."

It's the best evidence yet for the force behind reionization, but there's more work to be done. The researchers looked at one small patch of the sky; they need to make sure that their sample isn't just an anomalous cluster of dwarf galaxies, but is a representative sample of the entire population in the cosmic dawn.

They intend to study more cosmic lens regions of the sky to obtain a wider sample of early galactic populations. But just on this one sample, the results are incredibly exciting. Scientists have been chasing answers on reionization for as long we've known about it. We're on the brink of finally blowing away the fog.

"We have now entered uncharted territory with the JWST," said astrophysicist Themiya Nanayakkara of Swinburne University of Technology in Australia.

"This work opens up more exciting questions that we need to answer in our efforts to chart the evolutionary history of our beginnings."

The research has been published in Nature.

A version of this article was originally published in March 2024.

The devastation of Pompeii by the eruption of Vesuvius in 79 CE is one of the best-recorded disasters in human history. The ash and pumice that rained down preserved traces of the dying where they fell, leaving us to guess the identities and relationships of the people left frozen in time.

But we humans are imperfect. We navigate the world with perceptions and biases that cloud our observations, no matter how we try to remain objective. A new analysis of DNA retrieved from the victims of Pompeii reveals our assumptions about them were wrong – a discovery that is giving us insight into the bustling life of Pompeii, before a volcano snuffed it out.

"The scientific data we provide do not always align with common assumptions," says geneticist David Reich of Harvard University.

"For instance, one notable example is the discovery that an adult wearing a golden bracelet and holding a child, traditionally interpreted as a mother and child, were an unrelated adult male and child. Similarly, a pair of individuals thought to be sisters, or mother and daughter, were found to include at least one genetic male. These findings challenge traditional gender and familial assumptions."

The volcanic material dumped on Pompeii when Vesuvius exploded acted as a sort of flash fossilization process. It fell on and around the dead and dying, then set in place. When the bodies succumbed to time and decay, they left hollow impressions behind ash.

The ruins were rediscovered in the 19th century; in the 1870s, plaster was poured into the hollows to create casts of the bodies that had created them. But the shapes of the bodies weren't the only thing preserved. The bones left behind were also sealed into the plaster.

The archaeologists who made the casts in the 19th century couldn't have foreseen the emergence of future technology; nevertheless, their work would prove invaluable more than 150 years later. That's because the casts give us context for details preserved in the genetic makeup of the victims, which in turn helps us understand life in Pompeii and Roman-era Italy.

The analysis, led by forensic archaeologist Elena Pilli of the University of Florence in Italy, was conducted on fragmentary skeletal remains from 14 plaster casts, selected from 86 casts that are currently undergoing restoration. This is no easy task, anthropologist Alissa Mittnik of Harvard University and the Max Planck Institute for Evolutionary Anthropology in Germany told ScienceAlert.

"Both the extreme heat during the volcanic eruption and the plaster casting process could be detrimental for long-term DNA preservation. In genetic analyses, we usually try to target skeletal elements that are known to preserve DNA exceptionally well, such as the inner ear portion of the skull or teeth," she explained.

"In this study, we had to be less selective, as we were only able to take samples from the parts of the skeletons that were exposed in damaged casts that were undergoing restoration. The difficulty of obtaining ancient DNA under these circumstances is evident in the fact that only six of 14 sampled individuals provided us with genetic data."

But those six individuals were sufficient to provide a significant challenge to what we thought we knew about the victims of Pompeii.

The casts are excellent, but not perfect, and details can be a little hard to gauge, just by eye, so archaeologists relied on other clues. The ostentatious golden bracelet worn by the person embracing a child was thought to be women's jewelry. The tender affection with which each pair embraced was interpreted as feminine. Both of these assumptions, it turns out, were incorrect.

At the House of the Golden Bracelet, four individuals interpreted as parents and their two children were not genetically related to each other. At least one individual in the embracing pair was a man – and likely the other was, too.

The findings hint at a much deeper, more complex society than we had imagined for Pompeii.

"I had encountered the conventional narratives surrounding some of these groups of victims before studying them scientifically and they seemed plausible to me, therefore I was quite surprised to see that the genetic results uncovered that there is more to these people's stories than 'what meets the eye'," Mittnik told ScienceAlert.

"The findings make us reconsider simplistic interpretations of gender and family dynamics in Roman society that might not reflect modern western intuitions."

The analyses also revealed a greater genetic diversity in Pompeii than was suspected. The individuals studied were mainly descended from relatively recent immigrants from the eastern Mediterranean and Near East, rather than the people who had lived in the local region for centuries.

This is similar to diversity seen more broadly across the Roman region of western Italy, reflecting early forays into globalization, facilitated by strengthening trade across the Roman Empire.

And this is just six individuals in a city of thousands. It's a staggering result. Not only does it give us a new glimpse into the lives of people who lived thousands of years ago, it's a sobering reminder to try and check our biases at the door if we want to conduct an accurate study of human history.

"While our findings allow us to challenge some of the traditional narratives, we must be careful not to repeat the same mistake," Mittnik told ScienceAlert. "Instead, our results emphasize the importance of integrating various lines of evidence and of not superimposing modern assumptions onto ancient contexts."

The research has been published in Current Biology.

It seems like Roald Dahl may have been onto something after all: if you hurt a plant, it screams.

Well, sort of. Not in the same way you or I might scream. Rather, they emit popping or clicking noises in ultrasonic frequencies outside the range of human hearing that increase when the plant becomes stressed.

This, according to a study published in 2023, could be one of the ways in which plants communicate their distress to the world around them.

"Even in a quiet field, there are actually sounds that we don't hear, and those sounds carry information. There are animals that can hear these sounds, so there is the possibility that a lot of acoustic interaction is occurring," said evolutionary biologist Lilach Hadany of Tel Aviv University in Israel.

"Plants interact with insects and other animals all the time, and many of these organisms use sound for communication, so it would be very suboptimal for plants to not use sound at all."

Plants under stress aren't as passive as you might think. They undergo some pretty dramatic changes, one of the most detectable of which (to us humans, at least) is the release of some pretty powerful aromas. They can also alter their color and shape.

These changes can signal danger to other plants nearby, which in response boost their own defenses; or attract animals to deal with the pests that may be harming the plant.

However, whether plants emit other kinds of signals – such as sounds – has not been fully explored. A few years ago, Hadany and her colleagues found that plants can detect sound. The logical next question to ask was whether they can produce it, too.

To find out, they recorded tomato and tobacco plants in a number of conditions. First, they recorded unstressed plants, to get a baseline. Then they recorded plants that were dehydrated, and plants that had had their stems cut. These recordings took place first in a soundproofed acoustic chamber, then in a normal greenhouse environment.

Then, they trained a machine learning algorithm to differentiate between the sound produced by unstressed plants, cut plants, and dehydrated plants.

The sounds plants emit are like popping or clicking noises in a frequency far too high-pitched for humans to make out, detectable within a radius of over a meter (3.3 feet). Unstressed plants don't make much noise at all; they just hang out, quietly doing their plant thing.

By contrast, stressed plants are much noisier, emitting an average up to around 40 clicks per hour depending on the species. And plants deprived of water have a noticeable sound profile. They start clicking more before they show visible signs of dehydrating, escalating as the plant grows more parched, before subsiding as the plant withers away.

The algorithm was able to distinguish between these sounds, as well as the species of plant that emitted them. And it's not just tomato and tobacco plants. The team tested a variety of plants, and found that sound production appears to be a pretty common plant activity. Wheat, corn, grape, cactus, and henbit were all recorded making noise.

But there are still a few unknowns. For example, it's not clear how the sounds are being produced. In previous research, dehydrated plants have been found to experience cavitation, a process whereby air bubbles in the stem form, expand and collapse. This, in human knuckle-cracking, produces an audible pop; something similar could be going on with plants.

We don't know yet if other distress conditions can induce sound, either. Pathogens, attack, UV exposure, temperature extremes, and other adverse conditions could also induce the plants to start popping away like bubble wrap.

It's also not clear whether sound production is an adaptive development in plants, or if it is just something that happens. The team showed, however, that an algorithm can learn to identify and distinguish between plant sounds. It's certainly possible that other organisms could have done the same.

In addition, these organisms could have learned to respond to the noise of distressed plants in various ways.

"For example, a moth that intends to lay eggs on a plant or an animal that intends to eat a plant could use the sounds to help guide their decision," Hadany said.

For us humans, the implications are pretty clear; we could tune into the distress calls of thirsty plants and water them before it becomes an issue.

But whether or not other plants are sensing and responding is unknown. Previous research works have shown that plants can increase their drought tolerance in response to sound, so it's certainly plausible. And this is where the team is pointing the next stage of their research.

"Now that we know that plants do emit sounds, the next question is – 'who might be listening?'" Hadany said.

"We are currently investigating the responses of other organisms, both animals and plants, to these sounds, and we're also exploring our ability to identify and interpret the sounds in completely natural environments."

The research was published in Cell.

An earlier version of this article was published in March 2023.

The amount of sugar in the diets of babies and toddlers could predict their chances of developing type 2 diabetes and high blood pressure later in life.

Researchers from the University of Southern California, the University of California, Berkeley, and McGill University in Canada used a UK research database to investigate the long-term effects of sugar intake in our earliest years.

Collating data on 60,183 people born between 1951 and 1956, the team assessed the relationship between health and wartime sugar rationing; a restriction that ended in the UK in 1953, giving the team a very useful before-and-after boundary for comparison.

From January 1940 to 1953, the average British adult was limited to 41 grams of sugar a day, with no sugar allowed for children under the age of two. Once the restrictions were eased, sugar consumption rose sharply again.

"Studying the long-term effects of added sugar on health is challenging because it is hard to find situations where people are as-if randomly exposed to different nutritional environments early in life and follow them for 50 to 60 years," says University of Southern California economist Tadeja Gracner.

"The end of rationing provided us with a novel natural experiment to overcome these problems."

According to the data, children subjected to sugar rationing during the first 1,000 days of their lives – starting before they're born – had on average a 35 percent lower risk of developing type 2 diabetes as adults, and a 20 percent lower risk of developing hypertension.

Even in cases where rationing lifted while babies were still in the womb, there was a noticeably lower risk, accounting for up to a third of the risk reduction overall. What's more, when health conditions did appear, their onset was more likely to be delayed among those whose sugar intake had been restricted early in life.

"What's fascinating is that sugar levels allowed during rationing mirror today's guidelines," says economist Claire Boone, from McGill University.

"Our study suggests that if parents followed these recommendations, it could lead to significant health benefits for their children."

As striking as the results are, they're not enough to prove direct cause and effect. Though the researchers accounted for a number of potentially influential factors, Brits experienced a variety of cultural changes from the 1950s, not just their sugar intake.

Nevertheless, this is strong evidence that sugar early in life – and even before birth – is hugely influential. Next, the researchers want to study any possible links between sugar and other diseases, such as cancer.

"Sugar early in life is the new tobacco, and we should treat it as such by holding food companies accountable to reformulate baby foods with healthier options," says Paul Gertler, an economist from the University of California, Berkeley.

"We should also tax and regulate the marketing of sugary foods targeted at kids."

The research has been published in Science.

If you've ever thought to yourself, "Gee I sure would like to see some vampire bats on treadmills," then do we have the science for you. That's exactly what a team of scientists has done, and it's not because little Vladi needed to get his chiropteran steps in.

Rather, the new research reveals how vampire bats (Desmodus rotundus) make the most out of their primary food source – the blood they slurp from the mammals on which they feed.

Fascinatingly, the results show an aptitude for the metabolism of the amino acids in the blood they eat. And, moreover, it doesn't take them long to do so. A vampire bat can gallop merrily along, fuelled by a meal of blood consumed only minutes before.

This makes the vampire bat a very unusual animal indeed, since most vertebrates rely primarily on the metabolism of carbohydrates and lipids for energy. But the ability does appear elsewhere in the animal kingdom – in invertebrate animals, such as blood-feeding Tsetse flies.

It's well established that, among mammals, low-intensity aerobic exercise is predominantly fueled by lipids. As the exercise intensity increases, so too does the reliance on carbohydrates as fuel. These fuel sources are oxidized to generate adenosine triphosphate (ATP), the molecule that provides energy to living cells.

How exactly a vampire bat generates ATP from their extremely protein-rich diet was unclear. But physiologists Giulia Rossi of the University of Toronto and Kenneth Welch of McMaster University in Canada realized they could make use of a trait of vampire bats to find out.

Unlike other bat species, vampire bats are very good at running along the ground. So, they figured they could put bats in treadmills that measure their oxygen intake and carbon dioxide output to measure their metabolism as they exercise at different intensities. And, with the bats living temporarily in the lab, the researchers could control their food intake to determine how that metabolism was working.

They caught 24 wild adult vampire bats in Belize, and divided them into groups. One group of nine bats was fed cow's blood enriched with leucine, an essential amino acid (one that mammals can't synthesize) that helps build and repair muscles in humans. A second group of 12 bats was fed cow's blood enriched with glycine, a non-essential amino acid that helps build collagen and acts as a neurotransmitter.

By swapping the ordinary carbons in the amino acids for a relatively unique isotope, they could track what happened to the element as the compounds broke down in the bats' bodies.

The remaining group was fed cow's blood that was not enhanced with amino acids, to provide a baseline for the CO₂ production of an exercising bat.

After feeding, each bat was popped on the treadmill, custom-built for this research. There were three exercise intensities; 10 meters (33 feet) per minute, 20 meters per minute, and 30 meters per minute. The treadmill gradually increased to each target speed, and the bat's breath recorded as it scampered along the conveyor belt. At top speed, there were even little airborne hops.

Once the bats had been put through their paces, the researchers analyzed the rate at which oxygen was consumed, and carbon dioxide produced, the ratio of which is routinely used as an indicator of metabolic fuel use.

The isotopes revealed the production of CO₂ from the metabolization of amino acids was almost immediately present in the breath of bats on the treadmill. This suggests that the animals were rapidly and efficiently making use of their recent protein meals, unlike insects such as mosquitoes which take longer to metabolize the amino acids in the blood on which they feed.

Interestingly, the bats fed the enriched blood showed no discrimination between essential and non-essential amino acids. Their little bodies made the most of the resources provided, whatever those resources were.

"Our findings suggest that major enhancement of flux through these and related metabolic pathways have evolved in vampire bats as an adaptation to make efficient use of those fuels ingested in abundance (i.e. blood proteins and amino acids)," the researchers write, "marking a striking example of convergent evolution among both vertebrate and invertebrate obligate blood-feeding animals."

No bats were harmed in the making of this research. They may, however, have been a little more in shape upon their release back into the wild.

The research has been published in Biology Letters.

Medications like Ozempic and Wegovy are famous for their weight loss benefits, but some scientists want to know more about how these drugs impact muscle loss.

In a new commentary for The Lancet, an international team warns there is not enough research on how muscles are affected by GLP-1 receptor agonists.

The authors acknowledge that GLP-1 agonists have "shown substantial benefits" for many people around the world. Initial studies find the medications, which were first approved to treat type 2 diabetes, can also make it easier to lose weight.

Even those who don't lose weight show improved kidney health and heart health, reducing their risk of stroke or cardiac arrest.

Despite all the good news, the scientists are concerned by preliminary results on GLP-1 agonists, which show slightly higher rates of non-fat tissue loss compared to weight loss from non-pharmacological means.

The loss of fat-free tissue may not be fully representative of muscle loss, nor is a loss of muscle mass necessarily a bad thing for strength or movement. But dietician Carla Prado, biomedical researchers Stuart Phillips and Steven Heymsfield, and nutritionist Cristina Gonzalez say we can't know for sure without further evidence.

"At the time of writing, there are no data to establish whether treatment with GLP-1 receptor agonists is associated with physical frailty or [a loss of muscle mass]," the team writes.

"These effects would require long-term studies, which are not yet available, and the studies conducted to date were not designed to answer these questions."

While initial studies suggest strength is not impacted by the weight loss associated with GLP-1 agonists, the authors note that strength "is only one aspect of muscles' importance."

Beyond movement, they explain, muscles play crucial roles in our body's metabolism, our immune function, and in our response to stress and trauma.

Besides all of that, muscle mass also helps the body take up glucose in response to insulin.

The researchers worry that muscle loss could be further exacerbating risk factors associated with GLP-1 agonists in some patients, such as metabolic dysfunction, inflammation, poor dietary intake, and low physical activity.

Given the risks, the authors conclude that "these highly effective medications should be used strategically. This strategy can be accomplished with concurrent nutrition and exercise interventions."

Studies have shown that after weight loss, a decrease in skeletal muscle mass can be partly mediated through increased protein intake or exercise. By some estimates, resistance exercise can actually attenuate losses in fat-free mass by 50 to 95 percent.

Such results add weight to the idea that exercise programs and nutritional advice should be prescribed alongside GLP-1 agonists for the best results.

Typically, once a person stops taking these appetite-suppressing medications, they regain about two-thirds of their lost weight in a year. In a recent clinical trial, however, those who partook in supervised exercise programs did better at maintaining their weight loss.

"Additionally," the team writes, "ongoing studies are exploring ways to prevent or mitigate muscle loss with drugs… which could offer solutions for preserving muscle mass in individuals undergoing weight loss treatments."

The potential for muscle loss doesn't mean patients should stop taking GLP-1 agonists, but given how important muscles are for human health, the researchers argue we need to know more.

The commentary was published in The Lancet: Diabetes & Endocrinology.

One bizarre marine creature has taken this approach to dire situations quite literally, regressing its physical adult body to a juvenile stage once the stress of starvation or injury has subsided.

Until now, the immortal jellyfish (Turritopsis dohrnii) was the only species thought to be able to wind back the clock on jelly-puberty like this, but now it's joined by Mnemiopsis leidyi, better known as the sea walnut or the warty comb jelly.

We already knew comb jellies were pretty special: Their regeneration abilities are unmatched, they can fuse together to survive major injuries, they only form a butthole when they actually need it, and with total disregard for the usual rules of biology, they can reproduce sexually in their so-called larval stage.

Previous studies had also observed M. leidyi reducing its size and body mass considerably during starvation as a way of surviving leaner times, but experiments ruled out reverse-aging under these conditions.

Marine biologist Joan Soto-Angel, from the University of Bergen in Norway, was confused when an adult sea walnut he was keeping in a laboratory tank, with its plump gelatinous lobes that define adulthood in this species, suddenly disappeared. In its place pulsed a larva, more walnut-shell-shaped than any adult of its kind.

He sensed the existing research might not be the full story, and so in collaboration with Michael Sars Center colleague, Pawel Burkhardt, set out to check whether this jelly had somehow pressed rewind on aging.

They kept 65 healthy adult comb jellies isolated in tanks, all of which had completely reabsorbed the tentacles of their youth, another defining feature of their maturity.

All were starved for 15 days, and then fed once a week with a small amount of rotifers, a much leaner diet than usual, and as expected, began to quickly shrink.

When their adult lobes began to 'reabsorb' into their diminishing bodies, feeding was resumed every second day. And Soto-Angel knew he was onto something.

Fifteen of these jellies also had lobes surgically removed at the start of the experiment, adding a further stressor that the previous experiments hadn't captured.

"Over several weeks, they not only reshaped their morphological features, but also had a completely different feeding behavior, typical of a cydippid larva," Soto-Angel says.

"Witnessing how they slowly transition to a typical cydippid larva, as if they were going back in time, was simply fascinating."

The experiment showed the jellyfish could revert to a youthful form when stressed only by starvation, but this was far less common than in the lobectomy group: Only seven of the 50 starved jellies fully reverted, while six out of the fifteen injured animals were the jelly equivalent of '17 again'.

This also means many of the juvenile jellies in experiments and records might not have been as youthful as they seemed.

"It will be interesting to reveal the molecular mechanism driving reverse development, and what happens to the animal's nerve net during this process," says collaborator Pawel Burkhardt, who is leading investigations into the evolutionary origins of neurons.

"The fact that we have found a new species that uses this peculiar 'time-travel machine' raises fascinating questions about how spread this capacity is across the animal tree of life," Soto-Angel says.

This research was published in Proceedings of the National Academy of Sciences.