How Brown Tree Snakes Became an Unstoppable Invasive Species

BY T. DINKI, U. AT BUFFALO, JULY 28, 2026

https://scitechdaily.com/how-brown-tree-snakes-became-an-unstoppable-invasive-species/

Brown tree snakes are an invasive species in Guam.

 Credit: Bjorn Lardner, United States Geological Survey

Biologists have long wondered how such a small number of individuals from the invasive species managed to colonize the island so successfully.

Few invasive animals have reshaped an ecosystem as dramatically as the brown tree snake, a species commonly used in textbooks to illustrate the damage biological invasions can cause.

Native to Australia and the South Pacific, the snake reached Guam sometime after World War II, possibly as a stowaway on cargo aircraft. It has since eliminated many native forest birds from parts of the island and causes hundreds of electrical outages each year by climbing utility poles. In some areas of the U.S. territory, populations reach as many as 30,000 snakes per square mile.

That extraordinary expansion has long puzzled biologists. Guam’s population apparently began with only a small number of snakes, so extensive inbreeding should have reduced their capacity to adapt and limited their growth.

Hidden DNA changes may explain success

The snakes may carry far more genetic variation than earlier methods could detect, according to a University at Buffalo-led study published on July 24, 2026, in Science Advances.

Researchers from UB and the U.S. Geological Survey (USGS) used advanced long-read sequencing to examine large sections of the brown tree snake genome. They uncovered thousands of structural variants, including duplicated, deleted, and rearranged stretches of DNA, many of them concentrated in genes connected to immunity and smell.

This overlooked variation may help explain how a population established by only a few individuals survived a severe genetic bottleneck and became so successful.

Brown tree snakes are skilled climbers and mostly active at night.

 Credit: USGS



“The brown tree snake is maybe not wildly diverse, but it has important sources of genetic diversity that have been underappreciated,” says the study’s corresponding author, Trevor Krabbenhoft, PhD, associate professor in the UB Department of Biological Sciences.

For agencies that have spent decades attempting to contain the snakes on Guam, the results may be discouraging. For conservation biologists, however, they suggest that endangered and inbred populations could retain more capacity to adapt than previously recognized.

“It’s possible that endangered species may have more flexibility in their genes than we realize,” says first author Christopher Osborne, PhD, a former PhD student in Krabbenhoft’s lab and now an aquatic biologist with State University of New York Oswego. “We’re now getting a better understanding of unappreciated sources of genetic diversity that may explain how some inbred species can still respond to their environment.”

Long reads expose missing variation

Traditional assessments of genetic diversity often focus on differences in individual DNA letters, such as changing an A to a G or a T to a C. Early sequencing technologies largely restricted researchers to finding these single-base-pair differences.

Long-read sequencing can examine much larger sections of DNA and detect structural variants affecting at least 50 base pairs at a time. Across the genome, these large changes involve nearly eight times more DNA than single base-pair variations.

“It’s like looking at portions of two books letter by letter with a magnifying glass and thinking they’re the same, but not realizing entire paragraphs have been moved around or duplicated. Older sequencing technology didn’t allow us to easily see that DNA in one individual might be in a completely different place on the chromosome than in another,” says Levi Gray, PhD, a postdoctoral researcher in Krabbenhoft’s lab. “How we define genetic diversity and how we actually measure it is shaped largely by the technology of the day.”

Gray had previously investigated Guam’s brown tree snake problem while working with the USGS. That connection gave the researchers access to DNA provided by the USGS Brown Treesnake Rapid Response Team (RRT), which works to prevent the species from spreading elsewhere in the U.S. and its territories.

Immunity and smell genes stand out

Analysis in Krabbenhoft’s laboratory identified more than 19,000 structural variants in the brown tree snake genome. Each marks a location where stretches of DNA differ through duplication, deletion, or rearrangement.

The variants were not spread evenly throughout the genome. Instead, they appeared especially often in genes related to immune function and olfaction, the sense of smell.

Brown tree snakes depend heavily on smell to find food, using their forked tongues to collect chemical signals from the air. The unusual diversity in their olfactory genes may help explain a behavioral difference between populations. In their native range, the snakes sometimes eat other snakes, but there is little evidence of this behavior on Guam.

“The snakes’ heightened sense of smell may allow them to recognize one another as something more like siblings — especially given the high levels of inbreeding — than as prey,” Gray says.

The variants’ origins remain unknown

Researchers still do not know whether these structural variants existed before brown tree snakes reached Guam or developed afterward. Large-scale genomic changes usually build up across many generations, although some research suggests that severe population bottlenecks can speed their formation.

“Is it possible some of this diversity emerged after the invasion? It is, but we would have to sequence snakes from the native populations to know for sure,” Gray says.

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Feeling a Presence, Seeing Visions, Déjà Vu? Huge Study Maps The 'Uncanny' Experiences We Rarely Talk About

06 August 2026, By M. IRVING

https://www.sciencealert.com/ever-experienced-something-you-cant-explain-detailed-study-investigates-how-people-deal-with-the-uncanny

(David Wall/Moment/Getty Images)

Have you ever heard a voice when you were completely alone? Or felt the presence of some unseen being?

You're not alone; around 60 percent of Americans believe they've had some kind of unexplainable experience.

But was it scary? Inspiring? Perhaps it invoked a new spirituality in you, or made you feel closer to a deceased loved one.

Or maybe it just sent you to the doctor for a brain scan.

Whatever happened, and however you responded to it, there isn't much research into how humans process weird events.

So, social psychologists at the D'Or Institute for Research and Education (IDOR) in Brazil set out to investigate just that, for a new paper published in PLOS One.

The team built on a previously developed questionnaire called the Inventory of Nonordinary Experiences (INOE), which asks participants whether they've ever experienced any of 38 spooky happenings and, if so, the context and aftermath of the event.

The researchers then gave their new 47-question quiz to 5,117 people in Brazil before conducting statistical analyses of the results.

The outcomes are as intriguing as you'd expect.

Out-of-body experiences were one of the 'nonordinary experiences' in the questionnaire. 

(sdominick/E+/Getty Images)



"Experiences like sensing a presence, having a vision, or feeling as though you are observing yourself from outside your own body are far more common in the general population than clinical diagnosis rates would suggest," says senior author Ronald Fischer, a psychologist at IDOR.

"We observed that most people in our sample of over 5,000 participants who report them are not unwell, and most describe them as neutral or positive – both at the time they occur and also when looking back and reflecting on that experience."

Things that constituted a 'nonordinary' event included sudden, overwhelming feelings like joy, awe, or fear; seeing visions; hearing voices; out-of-body experiences; a sense of diminished self; feeling the presence of the deceased or extraordinary forces; deja vu; extrasensory perception; near-death experiences; lucid dreams; or a sense of having lived past lives.

If participants responded that they had experienced any of these, they were then asked a few questions about the context of their experience. That included their mental state – such as whether they were awake and alert, dreaming, just falling asleep or waking up, or under the influence of drugs or alcohol – and where they were at the time.

The participants also had to answer how long the experience lasted, how often it happened to them, and the rough age they were when it occurred or started.

Next, they were asked who or what they felt was responsible, such as gods, angels, demons, spirits, or other entities; and why they might have been 'chosen' for the experience.

Many people reported feeling a 'presence'. 

(Catherine McQueen/Moment/Getty Images)



Finally, the participants were asked whether the experience had helped or hindered what they were doing at the time, how pleasant or uncomfortable the experience was, and what impact it had on their life afterward.

The results were intriguing.

More than 60 percent reported having their experiences while awake and alert, and almost 40 percent were alone at the time. About 36 percent said their experience lasted a few minutes, while 27 percent said it was very quick or almost instantaneous.

Roughly 19 percent couldn't keep track of time during the event.

The most common number of occurrences for a single person was, surprisingly, two to three times, with 38 percent of the respondents. Another 30 percent said the experience had happened just once.

Two-thirds said the experience occurred or began when they were adults, while more than 20 percent reported something strange during their adolescence.

Interestingly, when asked who they believed was responsible for their experience, 36 percent reported that they didn't believe that anyone caused it. A god or gods was the next highest, at 16 percent, while 11 percent attributed it to some kind of holy spirit.

Following a similar pattern, when participants were asked why it happened, 41 percent attributed it to random chance, while 28 percent said it was a 'sign' or a message.

Participants were fairly evenly split on whether their experiences were something that science could or eventually would be able to explain. But the scales were tipped ever-so-slightly towards the answer that 'no, something else is involved.'

Almost half of participants said that they felt joy or well-being during their experience, while less than a quarter experienced suffering or discomfort.

About half also reported that they felt positive or very positive effects on their lives afterward, while less than 15 percent reported negative effects.

"For many people, such experiences can be meaningful and lead to personal growth and insight," says Fischer.

"Highlighting these possible positive outcomes is important to help people make sense of them and help to normalize them."

The researchers say that these kinds of experiences are largely unstudied academically. But regardless of what's actually going on, understanding them in more detail could help support people who report strange things.

"Importantly, we hope our work can help to remove stigma by focusing on the diverse ways that people experience and make sense of them," says Fischer.

"However, we would also stress that if people feel that these experiences interfere with their daily activities, then they should talk to a professional or seek help from somebody that they trust."

The Life of Earth

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'Only One Conclusion': Radical Study Suggests Life on Earth Arose Twice

06 August 2026, By M. Irving

https://www.sciencealert.com/radical-study-suggests-life-on-earth-arose-from-non-living-matter-twice

(witsawat sananrum/iStock/Getty Images Plus)

The fact that you, or I, or any living creature, is here at all is a series of astonishing strokes of luck stretching back more than 4 billion years.

One of the biggest hurdles was the very first one: How did life emerge from a primordial soup of stuff that very much wasn't alive?

A radical new study, published in Science Advances, suggests that this unlikely threshold may actually have been crossed not once, but twice.

Two of the main lineages of life – bacteria and archaea – may have independently figured out the secrets of metabolism that upgraded them from non-living to living, according to the new study, which focused on the most rudimentary set of chemical reactions thought to enable this transformation.

"The surprise is that the enzymes that catalyze those reactions are not conserved across the evolutionary divide that separates bacteria and archaea," says William Martin, a biologist at Heinrich Heine University Düsseldorf in Germany.

"The new data leave only one conclusion. The bacterial and archaeal lineages made the transition to the free-living state independently. Only free-living cells are alive.

"Let's call it by name: we are looking at one origin of the genetic code, but two origins of life."

That's a huge claim to make, especially when defining what life even is can be surprisingly tricky.

https://www.youtube.com/watch?v=nNK3u8uVG7o

Generally speaking, life is considered matter that responds to its environment, takes in energy, grows, and reproduces itself.

That sounds like it should cover the basics, but even that broad a statement is imperfect. After all, viruses can do most of those, but aren't traditionally considered 'alive'.

One aspect of life that is universal – and which viruses lack – is metabolism, the collection of chemical reactions that organisms use to make molecules that are vital for their everyday functioning.

Enzymes are the workhorse proteins that act as catalysts for these reactions in organisms, but that raises a weird chicken-and-egg question.

Enzymes themselves are products of chemical reactions – so how did the first lifeforms begin metabolizing things, including making enzymes, without the help of other enzymes?

The answer, it seems, lies in their surroundings.

It's generally believed that the first life arose in extremely reactive environments, such as hydrothermal vents. Metals that naturally occur in these places could have been the first catalysts for metabolism, converting compounds like hydrogen gas, ammonia, and carbon dioxide into other useful molecules.

"Almost everything about the origin of metabolism is debated, including the roles of energy, genetics, autocatalysis, phosphate, cofactors, cyanide, CO2, and water," Martin and colleagues write in their paper.

"Yet on one aspect all will agree: the ~400-reaction network that converts H2, CO2, NH3, H2S and phosphate into amino acids, bases and cofactors cannot have arisen in an instant.

"Its emergence from spontaneous environmental reactions had to traverse intermediate states of assembly, which have previously been elusive."

The researchers investigated the protein structures of core metabolic enzymes in the genomes of bacteria and archaea, and developed a method and algorithm to order them in complexity. From there, they could determine which ones evolved in which order, and put together a rough timeline.

Starting compounds are shown at the left; they are converted by metabolism into the building blocks of life. The 420 enzymatic reactions are indicated as circles, and chemical metabolites as diamonds; lines connect reactions that share metabolites. Circles shown in magenta shading indicate reactions that could have been catalyzed by inorganic compounds in the environment where metabolism of the first cells arose. 

(HHU/Nadja Hoffmann)



"We found that the last universal ancestor of all cells, LUCA, possessed enzymes for only about half of the reactions of metabolism," says Martin.

"The other half was catalyzed by metals in the environment where LUCA arose."

The team found that there were likely four different phases in the development of catalysis (enzyme-driven reactions). The first relied solely on metals in the environment.

Once enough of the useful molecules built up, the not-quite-living-yet proto-cells (which included LUCA) could start developing their own enzymes that performed some of the functions of those metal catalysts.

Over time, later proto-cells developed more and more enzymes, reducing their dependency on external metals, until they no longer needed them at all. Only at that point would they be considered 'free-living cells'.

Importantly, the researchers say, this didn't occur until after bacteria and archaea had separated. These two branches figured out their own ways to tackle the same problems.

"We can see cases where the ancestors of bacteria and archaea independently evolved structurally distinct enzymes to catalyze the same essential metabolic reaction," says Natalia Mrnjavac, a biologist at Heinrich Heine University Düsseldorf.

"Such parallel inventions could have paved the way to the independent emergence of free-living bacteria and archaea."

The study may also plug another gap in our understanding of the origins of life.

A molecule called ATP is now a vital energy source to fuel metabolism – but it's also made by enzymes, and wasn't available in prebiotic chemistry. The researchers say they identified an alternative.

"When we react phosphite, a form of phosphorus that naturally occurs in hydrothermal vents, with organic compounds, we get metabolic phosphorylation reactions overnight in water," says Manon Schlikker, a molecular evolutionary scientist at Heinrich Heine University Düsseldorf.

"Phosphite and palladium replace ATP and enzymes; it's amazing, and it makes early evolution a lot easier to grasp."

Yet critical to chemical reactions is the medium in which they occur, and scientists still don't have a clear idea about that. Was it water, or a sticky goo?

If the findings are backed up with further research, it seems that the tree of life, as we picture it, may need an update. We tend to think of LUCA as the 'trunk' of the tree, with all the other lifeforms, past and present, branching off from there.

But perhaps there were two completely separate trunks, which first diverged at the roots, before they were even technically alive.

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Drug-Resistant Bacteria May Be Jumping Between Pets And Humans, Scientists Warn

26 July 2026, By F. MacDonald

https://www.sciencealert.com/drug-resistant-superbugs-may-be-jumping-between-pets-and-humans-scientists-warn

(Clouds Hill Imaging Ltd./Getty Images)



In 2022, a batch of chicken and duck embryos that died before hatching arrived at a veterinary lab in China for testing.

Buried in their brain tissue, researchers found Acinetobacter baumannii – a pathogen labelled 'Priority 1′ by the World Health Organization'. It's best known for tearing through hospital ICUs due to its resistance to even last-resort antibiotics.

It's also more recently starting to become recognized as being zoonotic: capable of moving between animals and people.

It's long been thought that livestock may play a role in spreading drug resistance in superbugs.

But, interestingly, the specific strains of bacteria isolated from the poultry weren't actually resistant to much of anything.

https://www.youtube.com/watch?v=PcYOc-LxZzs

When comparing this genetic data to that found in humans and companion animals such as cats and dogs, the researchers from Nanjing Agricultural University, Wuhu Institute of Technology, and Nanjing University of Chinese Medicine in China found that the real concern turned up somewhere closer to home.

Researchers pulled together genetic data on 509 A. baumannii samples collected from animals in 17 countries, spanning 33 species – everything from white storks in Poland (which, oddly, make up a vast proportion of the animal samples on record) to cats, dogs, and horses in veterinary clinics across Europe.

Combined with thousands of human clinical samples from the same regions, plus the new poultry data, the picture that emerged wasn't reassuring for pet owners.

"A. baumannii isolated from animals can be divided into two groups: a high antimicrobial resistance (AMR) group dominated by hosts such as horses, cats, and dogs and a low AMR group dominated by hosts such as livestock, poultry, and wildlife," the researchers, led by Xiangkuan Zheng at Nanjing Agricultural University, wrote in the journal Applied and Environmental Microbiology.

(NickyLloyd/E+/Getty Images)



Using a classification system that groups related A. baumannii strains into "international clones" – the same lineages behind hospital outbreaks worldwide – the team found that several of these clones, including one called ST25, turned up again and again in companion animals.

ST25 alone was found in nine different animal species, mostly cats, dogs, and horses.

Bacteria from cats, dogs, and horses turned out to be genetically almost indistinguishable from strains infecting people in hospitals nearby, with genome similarity scores above 99 percent, and in some cases over 99.5 percent.

Livestock, poultry, and wild animals, by contrast, carried strains that were far more distant relatives – typically just 97 to 98 percent similar to the human strains.

"Our study suggests that A. baumannii has a higher potential of intertransmission between companion animals and humans compared to livestock, poultry, and wildlife," write the researchers. "This elevated potential may be related to the close contact of companion animals with humans."

Cats and dogs even carried resistance genes that livestock never should. Isolates from companion animals turned up two genes that make bacteria resistant to carbapenems – the antibiotics doctors reach for when nothing else works, and which are off-limits in livestock farming altogether. Those same resistance genes turned up in precisely zero of the livestock, poultry, or wildlife samples.

None of this means your dog or cat has given you a hospital infection, or ever will.

Let's be clear: there's no direct evidence here of the bacterium actually jumping from a specific pet to a specific person, just a genetic paper trail suggesting the opportunity is there, and has been for a while.

Last year, the American Society for Microbiology (AMR) published an article exploring the emerging link between antibiotic-resistant bacteria in pets and humans – which specifically flagged the need for more species specific pathogen sampling to help further understand the picture moving forward.

While this latest study gives us more important clues, there's still a long way to go.

What happens next is more sampling – of paws, feathers, hooves, and the humans standing next to them – to work out how often, and how easily, this hospital regular slips between species.

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Humans and Mice May Process Smells in Very Similar Ways

By K. Samuelson, Northwestern U., August 4, 2026

https://scitechdaily.com/humans-and-mice-may-process-smells-in-very-similar-ways/

A mouse appears to sniff a flower. 

Credit: Michael Lynch

Every deliberate sniff may activate a brain system that has survived millions of years of evolution.

A mouse searching for food may sniff several times each second. A person checking whether a cantaloupe is ripe usually leans in for one slow, deliberate breath.

Those behaviors look completely different, but new research suggests the brain may treat them in much the same way.

Two complementary Northwestern University studies found that mice can perform a single intentional sniff, while humans use brain rhythms that closely resemble those seen in rapidly sniffing rodents. Together, the findings suggest mammals share an ancient neural system for gathering information through smell, even when their breathing patterns and behavior differ dramatically.

The studies were published together in Science Advances.

“The true similarity is this single sniff, but it’s not just a sniff,” said corresponding author John M. Barrett, research assistant professor of neuroscience at Northwestern University Feinberg School of Medicine. “Mice even move their hands while sniffing, which shows it’s volitional; they’re doing it on purpose.”

Co-corresponding study authors John Bartlett (center) and Mang Gao (right) and study co-author Rita Fischer (left) discuss the study in the lab of Gordon Shepherd on Northwestern University’s Chicago campus.

 Credit: Olivia Dimmer, Northwestern University



Different Sniffs, Same Brain Process

Smell begins with breathing, but it is not a passive sense. Animals actively control when and how they inhale, changing the flow of odor molecules into the nose and shaping the information sent to the brain.

Rodents are especially known for rapid sniffing. Humans breathe much more slowly, which raised a long-standing question: How can both species identify odors with similar speed and precision when their sampling rates are so different?

The Northwestern teams approached that puzzle from opposite directions. One group studied how mice coordinate breathing and movement while examining food. The other recorded activity directly from the human olfactory bulb, the brain structure that receives the earliest neural signals from the nose.

Their results converged on the same conclusion. Humans and mice appear to rely on a shared timing system for processing smells.
Why Sniffing Could Reveal Disease

That similarity matters because changes in sniffing have been associated with autism, Alzheimer’s disease, and Parkinson’s disease. Understanding how healthy smell circuits operate could help researchers recognize when those systems begin to break down.

“Knowing we have this evolutionarily conserved set of mechanisms helps us understand how mammalian brains work, which could ultimately help us understand how they fail in pathology,” said first author Andrew Sheriff. “It helps us know how the brain works so we know how to fix it when it doesn’t work.”

A study participant looks at a computer screen in the lab of Christina Zelano on Northwestern University’s Chicago campus.

 Credit: Kristin Samuelson, Northwestern University



The mouse study began with a small behavior that was easy to overlook. When mice handled food, they sometimes paused and lifted it toward their noses before eating. Rather than continuing their usual rapid sniffing, they appeared to take one carefully timed breath.

Researchers in the laboratory of Gordon M. G. Shepherd in the Department of Neuroscience at Northwestern University Feinberg School of Medicine worked with collaborators at the University of Pennsylvania and the University of Florida College of Medicine to investigate.

Led by Mang Gao and Barrett, the team created a robotic multi-camera system that followed freely moving mice as they searched for food and ate. The researchers tracked breathing along with movements of the animals’ heads and forepaws.

Breathing and Movement Work Together

The recordings showed that the mice timed one sniff to the exact moment food reached the nose. Their breathing, head position, and hand movements came together as a coordinated action.

This was not the same as the repetitive sniffing mice use while searching. It looked more like a quick inspection, similar to the way a person may raise food to the nose before deciding whether to take a bite.

The mice sniffed more strongly when handling less appealing food. However, odor alone did not trigger the behavior. When researchers disrupted the animals’ sense of smell, the mice continued performing the single food sniff. The behavior stopped only when the scientists silenced the motor cortex, a brain region involved in voluntary movement.

Corresponding author Andrew Sheriff adjusts a study participant’s EEG cap ahead of recording electrophysiological signals on a multi-contact electrode. 

Credit: Olivia Dimmer, Northwestern University



“This means when mice sniff food, they’re not doing it as a reflexive response to an odor, but rather as a proactive act of deliberate sensory sampling,” said Gao, a postdoctoral scholar in the Shepherd lab. “It turns out the mice choose to perform these quick ‘smell checks,’ which is characteristic of a lot of human olfactory behavior, rather than being passively triggered to sniff.”

The study is the first to document this intentional, non-reflexive sniffing behavior in rodents during natural foraging.

How Humans Process Odors So Quickly

The second study examined the problem from the human side. Researchers in Christina Zelano’s laboratory in the Department of Neurology at Feinberg, working with Dr. Bruce Tan in the Department of Otolaryngology at Feinberg, wanted to understand how people can recognize smells quickly despite inhaling far more slowly than rodents.

“We wanted to understand how we can identify odors as fast as rodents do even though we sniff over 10 times slower,” said Sheriff, a postdoctoral scholar in Zelano’s lab. “By recording directly from the human olfactory bulb using a novel technique, we were able to find rhythms of odor processing that closely resemble those of rodents, suggesting conserved time windows for olfaction across species.”

Using a minimally invasive, high-precision method developed in the Zelano lab, the team measured activity in the olfactory bulbs of healthy volunteers as they took one intentional breath. That single inhalation triggered low-frequency brain waves known as theta oscillations (2–8 Hz). The rhythm matched the same frequency range at which rodents repeatedly sniff.

One Breath, Multiple Brain Cycles

This means the human brain does not need to match each theta cycle with a separate breath. Instead, one slow inhalation can activate several internal processing cycles, allowing odor information to be divided and organized rapidly within a single sniff. The theta rhythm also helped structure faster bursts of neural activity associated with analyzing the smell itself.

In rodents, breathing and theta activity are so closely synchronized that they are difficult to separate. Human breathing is slower, making it possible to see that the brain rhythm can continue independently of the physical sniff.

“The implications of our findings are significant,” said co-author Qiaohan Yang, a graduate student in Northwestern University Interdepartmental Neuroscience. “In rodents, sniffing and theta are so tightly fused that the two are nearly indistinguishable. In humans, the slower sniff rate pulls them apart, revealing the theta oscillation as a distinct, independently generated rhythm that a single deliberate inhalation is sufficient to engage.”

Smell Is an Active Decision

The studies add to a broader understanding of perception as something the brain actively constructs.

A sniff is not simply air entering the nose. Its timing can be coordinated with movement, attention, expectation, and decision-making. Mice appear to choose when to perform a focused smell check, while the human brain uses one breath to create a rapid internal sequence for analyzing odor.

The difference between species may therefore lie less in the basic machinery than in how each animal uses it. Mice run the shared system through rapid breathing cycles. Humans compress similar neural timing into a slower inhalation. Both strategies allow the brain to collect information quickly enough to guide the next action, whether that means eating a crumb, rejecting spoiled food, or deciding that a piece of fruit is ready.

Together, the studies suggest that evolution did not invent a completely new olfactory system for humans. It retained the same core design and adjusted how that design operates within a very different pattern of breathing and behavior.

The Life of Earth

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There's One Predator That Terrifies Bears And Mountain Lions Alike

05 August 2026, By M. Starr

https://www.sciencealert.com/theres-one-predator-that-terrifies-bears-and-mountain-lions-alike

(Cris Cantón/Moment/Getty Images)

The wilds of North America can be a hazardous place.

It's there that some of the most intimidating predators make their home – black and brown bears that could eviscerate a person with one swipe of a mighty paw, and mountain lions that stalk almost silently on padded feet.

Many hikers will gird themselves against the possibility of an attack from one of these feared beasts – but, as two new papers explain, there's an animal out there that even the most formidable predators will try to avoid.

Us.

In fact, attacks by these animals are so uncommon that, in North America, people are far more likely to be struck by lightning.

The research suggests one reason why: bears and mountain lions go to remarkable lengths to stay away from humans whenever they can.

"These discoveries change the narrative about human-carnivore conflict," writes Yale University ecologist Oswald Schmitz in a Current Biology dispatch tying together two studies, one on bears and the other on mountain lions.

Mountain lions rarely attack humans.

 (Kathleen Reeder Wildlife Photography/Moment/Getty Images)

In North America, brown, or grizzly, bears (Ursus arctos) attack, on average, around 11.4 humans per year.

Mountain lions (Puma concolor) attack just 4 to 6 people per year, and the rate of black bear (Ursus americanus) attacks is unknown, but just 63 human fatalities due to black bear attacks were documented between 1900 and 2009.

By contrast, between the US and Canada, around 580 people are struck by lightning every year.

Looking purely at the numbers, lightning strikes outnumber brown bear attacks by roughly 50 to 1 (although, of course, the actual risk depends on other factors such as where you live and how much time you spend in bear-filled woods).

So why are these attacks so rare?

The answer, according to the two studies, is that these animals don't simply react to humans showing up. Instead, they actively change their behaviors to avoid us.

In a study led by wildlife biologist Philip Manlick of the USDA Forest Service, researchers studied black and brown bears feeding along salmon streams in southeast Alaska.

Motion-triggered speakers played recordings of either gull calls, off-road vehicles, or human voices whenever a bear approached. Cameras recorded what happened next.

The bears were twice as likely to beat a hasty retreat when they heard vehicle sounds compared to the gull sounds.

https://www.youtube.com/watch?v=sKL9HDh3M34

They were almost 10 times more likely to flee from the sound of human voices.

This has implications far beyond bear-human interactions.

Bears take the salmon they catch into nearby forests, leaving behind decaying remnants that help fertilize the ecosystem. Disrupting that nutrient transport has knock-on effects on other ecosystem processes.

Top left: A cinnamon-colored black bear and her cub flee after hearing human voices. Top right: Brown bears on alert after hearing engines from an off-highway vehicle. Bottom left: A bald eagle eats a freshly caught meal from the nearby stream, ignoring the control sounds of gull calls. Bottom right: A black bear continues to eat a salmon, ignoring the gull calls at a control site. 

(Forest Service photos)

The mountain lion paper, led by environmental scientist John Morgan of the University of California, Santa Cruz, told a similar tale.

The researchers analyzed 6 years of GPS data collected from 36 tagged wild mountain lions in the Santa Cruz Mountains. They mapped this data against data from the GPS fitness-tracking app Strava, which showed where and when people were hiking, biking, and using trails.

The mountain lions didn't just respond to the presence of humans. Rather, they seemed to anticipate where and when human activity was likely to be heavy, and proactively avoided those places at those times.

https://www.youtube.com/watch?v=t7CtjkZFTQs

Even when mountain lions lived in areas with lots of human activity, though, they were not more likely to attack. Any higher attack rates in those areas were better explained simply by more frequent encounters between people and mountain lions.

Taken together, the two studies suggest that the animals take actions that indicate they perceive humans as a significant threat.

Bears abandon their feeding opportunities. Mountain lions plan their movements around predictable human routines.

They're already doing a lot of the heavy lifting that prevents dangerous encounters with our own species.

For our end of the bargain, the mountain lion study suggests, we can try to avoid forcing them into situations where their avoidance strategies fail.

The popular image of the relationship between humans and carnivorous predators is that the predator is the aggressor, and the human is the helpless prey that stands to lose the most from an encounter.

In reality, Schmitz argues, humans have not just the power but the responsibility to do all that we can to keep those animals safe.

"By being cognizant of how they shape the landscape of fear experienced by carnivores and their prey species," he writes, "humans can proactively adjust their behavior and spatial use of landscapes in ways that can transform the human-carnivore relationship from one of conflict to one of coexistence and thereby rebalance the attendant cascading effects that human fear effects have on wildlife communities and ecosystems."

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New Research Questions Decades of Low-Fat Dairy Advice

By B. Zou, U. of Toronto, August 3, 2026

https://scitechdaily.com/new-research-questions-decades-of-low-fat-dairy-advice/

Full-fat dairy may have a more nuanced effect on the body than nutrition labels imply. Researchers found no meaningful adverse changes after regular consumption and observed several unexpected nutritional and cardiovascular signals. 

Credit: Shutterstock

Researchers found that people can consume three daily servings of full-fat dairy without adversely affecting body weight, body composition, energy metabolism, or blood lipid levels.

For years, people scanning the dairy aisle have often been steered toward skim milk and reduced-fat products, largely because full-fat dairy contains saturated fat. Yet the health effects of dairy may depend on more than the amount of fat listed on the label.

Research led by University of Toronto scientist Harvey Anderson found that adults could consume three servings of full-fat dairy each day without harmful changes in body weight, body composition, energy metabolism or blood lipid levels. The results were published in the Journal of Nutrition.

Testing full-fat dairy directly

To examine the effects under controlled conditions, Anderson and his colleagues recruited 74 adults with overweight or obesity and randomly placed them into one of three dietary groups. One group followed a low-dairy, calorie-restriction diet. A second consumed three daily servings of dairy while keeping calorie intake energy-neutral, meaning participants ate roughly the amount of energy their bodies used. A third group also consumed three daily servings but did not face calorie limits. All participants were encouraged to follow Canada’s food guide.

Harvey Anderson.

 Credit: Harvey Anderson


 
This design allowed the researchers to separate the effects of dairy from those of calorie restriction. After 12 weeks, participants consuming three servings of dairy showed no meaningful differences in weight gain, body composition or cholesterol compared with those eating the low-dairy diet.

The higher dairy groups also recorded lower blood pressure and consumed more calcium, protein and vitamin D, nutrients that support functions such as bone maintenance, muscle health and immune activity.

“Those who had three servings of dairy didn’t have adverse levels of blood cholesterol or lipids or evidence of insulin resistance,” says Anderson, a professor of nutritional sciences in U of T’s Temerty Faculty of Medicine.

Insulin resistance occurs when the body’s cells stop responding properly to insulin, the hormone that helps move sugar from the bloodstream into cells for energy. Over time, that reduced response can increase the risk of type 2 diabetes.

Guidelines face conflicting evidence

Nutrition guidelines in Canada and many other countries have long favored fat-free or low-fat dairy. The reasoning is that reducing saturated fat may help prevent high cholesterol and lower cardiovascular disease risk.

Human research, however, has not consistently shown that eating full-fat dairy leads to worse health outcomes, Anderson says. Some investigations have even identified possible protective effects. Those include recent work led by Kozeta Miliku, an assistant professor at Temerty Medicine.

The apparent contradiction may come from viewing saturated fat in isolation rather than considering the food that contains it. Anderson and other researchers point to the dairy matrix hypothesis, which proposes that a food’s physical structure changes how its nutrients are broken down, absorbed and used.

In practical terms, dairy is not simply a collection of separate nutrients. Its proteins, fats, minerals and other components are packaged together, and that arrangement may influence how quickly they reach the body and what effects they produce.

“With dairy products, it’s got two proteins – casein and whey – that are bound together with fat and with nutrients mixed in,” Anderson says, adding that it’s this unique and complex physical structure that is responsible for the slow and steady delivery of nutrients from dairy products, and that expands their health impacts to more than just the sum of the isolated nutrients.

Whole foods reshape nutrition advice

The findings may be particularly useful for older adults, Anderson notes. As people age, their overall energy needs often decline even though they still require adequate protein, calcium, vitamin D and other nutrients.

That creates a practical challenge. Older adults may need to obtain more nutrition from fewer calories. Dairy products offer a familiar source of concentrated energy and nutrients, Anderson says, and the study found no evidence that including them increased the risk of diabetes or other chronic diseases.

The results also support a broader shift in nutrition research. Instead of judging foods mainly by a single component, such as saturated fat, researchers and policymakers may need to consider how nutrients behave when consumed together in a whole food.

Faced with constantly changing trends in food and nutrition and sometimes conflicting messaging around diet, Anderson’s advice is straightforward: “Keep it simple, eat a variety of foods and not too much of anything.”

The Life of Earth

https://chuckincardinal.blogspot.com/

Ecosystems of Rock-Eating Fungus And Tardigrades Found Thriving Deep Within a Gas Shale

03 August 2026, By J. Cockerill

https://www.sciencealert.com/scientists-discover-entire-ecosystem-hundreds-of-feet-below-earths-surface-at-depths-thought-inhospitable-to-life

Researchers have cultured hundreds of fungal strains from water samples pumped out of gas wells.

  (Quinn Moon, University of Michigan)



Just about every corner of Earth we look at seems to hold signs of life.

Now, scientists have discovered evidence of a whole community of complex organisms – fungi, worms, and even tardigrades – that call the Antrim Shale home.

That's pretty surprising, given the Antrim Shale is an ancient deposit of organic-rich mud some 350 million years old that now serves as one of the United States' largest gas fields.

But when scientists got to look for DNA in the water being pumped up from wells dug 247 to 556 meters (810 to 1,824 feet) deep into the ground, they found an astonishing diversity of life.

Organic-rich rocks and water deep within the Antrim Shale teem with life. They are packed with fungi and other tiny organisms.

 (John Megahan/University of Michigan)

"Energy companies dig these wells and pump massive amounts of water out and strip the methane from the water," ecologist Quinn Moon, lead author of the study, told ScienceAlert.

Moon, who is based at the University of Michigan, worked with a team of mycologists and earth scientists to get a picture of the organisms that might be living in this seemingly inhospitable environment.

"We filtered huge quantities of water and extracted DNA from those filters. We also put the water onto nutrient media to grow the actual fungi," Moon explained.

"Many deep environments, including the Antrim Shale, have extensively been shown to contain bacteria and archaea."

That had him wondering what else might be living down there.

An astonishingly complex and lively ecosystem emerged.

"Our findings challenge the common assumption that fungal regulation of organic matter decomposition is constrained to surface ecosystems," Moon and his colleagues write in their scientific paper, which was recently published in The ISME Journal.

Within these water samples, they identified 689 likely species of fungi from snippets of their genetic material, and managed to grow 205 strains in the lab for better identification.

Thirteen of those fungal strains are thought to be entirely new to science.

One of the dominant classes of fungi was Agaricomycetes, which are probably the best-known kind of fungi because they're the ones that produce mushrooms, though it's unclear whether they'd actually be capable of producing the parasol-like caps so far below ground.

The researchers isolated and grew more than 200 kinds of fungi from the deep subsurface to better understand how fungi survive in extreme environments, how underground ecosystems function, and what happens to carbon stored in Earth's crust. (Ronan Montgomery-Taylor/University of Michigan)



But the metabolisms of this kind of fungi – along with the other dominant class Moon and team discovered, Dothideomycetes – may explain their success in the shale.

On the surface, both of these kinds of fungi are known to break down lignin and cellulose for energy. These are substances that other organisms struggle to digest.

"These fungi make a living by eating some of the carbon forms most difficult to break down," Moon told ScienceAlert.
 
"I think the explanation is, and this aligns with other data from the surface, that these wood decay mushrooms have the most extensive arsenal of enzymes that they use down there to break down lignin and cellulose in the shale (or compounds similar to lignin and cellulose)."

Research is ongoing to screen the fungi's ability to break down coal, shale, oil, plastic and other difficult substrates. (Quinn Moon, University of Michigan)



Fungi made up about one-sixth of the biomass in the water samples, with a relative abundance comparable to what is found in the open ocean and Antarctic soils: about 250 fungal cells in each drop of water.

Alongside these fungi, the scientists found genetic traces of rotifers (microscopic 'wheel animals' you might've seen in pond water), segmented worms, tardigrades, and roundworms.

They even found evidence of intracellular parasites such as Ichthyosporea, which infects animals, and Rozellomycota, which parasitize other fungi.

It wasn't possible for the researchers to get a clear sense of the oxygen levels available to these creatures, so it's still unclear exactly how they're surviving down there.

As they note in their paper, the process of pumping water to the surface can introduce dissolved oxygen to samples that may not actually be available all the way down.

Previous studies have found the Antrim Shale hosts many species of archaea that produce methane, which is a sign this subterranean environment is pretty low on oxygen.

Others suggest that even without a supply of oxygen from the surface, some microbes may be capable of actually producing large amounts of oxygen without the help of light.

The researchers used a stain to count the number of fungi cells within each sample taken from Earth's subsurface.

 (Quinn Moon/University of Michigan)



But based on oxygen and hydrogen isotopes in the water, and the salinity gradient across sample sites, the team believes this underground community has been enjoying relatively stable geochemical conditions ever since the Late Pleistocene.

Much of the water hauled up in this study had not seen the light of day for 11,000 years, Moon said.

The microbes' ancestors were probably first introduced to these deep subsurface environments when Late Pleistocene ice caps melted, and the water seeped into the shale's pores and cracks.

So not only are these fungi living their lives at unfathomable depths; they have probably been isolated there for millennia, adapting to a set of evolutionary pressures entirely different from their aboveground counterparts.

And, as humans so often do, we started disturbing them before we even realized they exist.

"These may be biodiversity hotspots, but are also hotspots for anthropogenic destruction," Moon told ScienceAlert.

"These deposits have so many wells dug into them, many injected with biocides, without us ever considering if these habitats have new species and how we can preserve them."

The researchers also point out that fungi – so often overlooked – really need to be incorporated into models of carbon cycling and sequestration in the subsurface.

About 90 percent of Earth's organic carbon is stored in the deep subsurface, so it's a pretty significant part of the equation when it comes to balancing our climate.

If these fungi, bacteria, and other organisms are actively using these deep rocks, that carbon may not be quite so 'sequestered' as we imagine.

"If there are many organisms that can eat it, those gases can rapidly be released to the atmosphere," Moon said.

The Life of Earth

https://chuckincardinal.blogspot.com/

This Tiny Organ Plays a Far More Profound Role in Human Longevity Than We Realized, Study Finds

04 August 2026, By P. Dockrill

https://www.sciencealert.com/this-organ-plays-a-far-more-profound-role-in-human-longevity-than-we-realized-study-finds

(janulla/Getty Images)

A small organ located in the upper chest has been plagued by an identity crisis for decades now.

The thymus, which plays a crucial role in early life in helping to develop children's immune systems, is known to decay and shrink with age, leading to it often being considered a relatively useless or defunct organ in adults.

But research is showing this maligned "immune cell graveyard" doesn't actually lose its purpose when we grow up, as many had thought.

In fact, recent research published in Nature suggests the thymus could have a persistent and profound impact on health and longevity throughout people's lifetimes, helping the body counter disease risk, including cancer.

"We suspected the adult thymus might still matter, but we were surprised," oncologist Hugo Aerts from Harvard University, director of the Artificial Intelligence in Medicine (AIM) Program at Mass General Brigham, told ScienceAlert.

"We did not expect these differences to be so strongly and consistently associated with longevity, cancer incidence, cardiovascular disease, and cancer therapy response across multiple large, independent cohorts. That suggested the adult thymus is far more important than previously appreciated."

In their study, Aerts and his team analyzed health data from over 27,000 people, collected in two separate cohorts, the Framingham Heart Study (FHS) and the National Lung Screening Trial (NLST).

https://www.youtube.com/watch?v=W67LzQF6YqQ

In each study, people had taken part in computed tomography (CT) scans, which measured the size, shape, and composition of their thymus.

This data was fed into a deep learning system that was able to quantify the health of their thymus, based on these differing characteristics.

The AI could then generate a thymic health score – a kind of proxy for how functional the thymus was in adulthood – classifying each person as having either low, average, or high thymic health.

Follow-up data from each cohort showed that thymic health was linked with dramatically altered health outcomes in the years following the CT scans.

After adjusting for age, sex, smoking, and comorbidities, the researchers found that participants in the NLST with high thymic health had a roughly 50 percent lower relative risk of death by 12 years later, when compared with individuals with low thymic health from the study.

Similarly, people with high thymic health were about 36 percent less likely to develop lung cancer, and about 50 percent less likely to die from lung cancer compared to the low thymic health group.

Illustrations of three representative examples of individuals with high, average, or low thymic health. The thymus bed is outlined in orange.

 (Bernatz et al., Nature, 2026)



Cardiovascular disease also showed considerable relative risk reductions, with high thymic health corresponding to 63 percent lower risk of cardiovascular death in the NLST, and up to 92 percent lower risk in the FHS, compared to those with low thymic health.

The findings warrant replication in future research, and only show correlations in the data; they can't definitively prove that having a healthier thymus leads to these gains in health.

But the results still go a long way to suggesting that we need to update our understanding of how the thymus may be contributing to adult health and lifespan.

"These findings change how we think about the immune system in medicine," Aerts told ScienceAlert.

"Our work suggests that thymic health is a fundamental component of that immune fitness and that it can now be measured using routine medical imaging. This opens the possibility of identifying patients who are most likely to benefit from certain therapies, tailoring treatments to preserve immune health, and developing new strategies to maintain immune function as we age."

In a separate but related Nature study led by Aerts and published alongside the first paper in March, the researchers found that thymic health was also linked to immunotherapy responses across several types of cancer, including lung cancer, melanoma, breast cancer, and others.

One takeaway is that the thymus might not only be an unappreciated factor boosting people's health and longevity – it could also help us develop and target new kinds of treatments.

"The first turning point came when we discovered that patients with healthier thymuses responded much better to immunotherapy and survived longer," Aerts said.

"That finding was surprising because the thymus has long been considered largely irrelevant in adults. Initially, we wondered whether this was something unique to cancer treatment.

"But as we expanded the research into large population cohorts, we found that thymic health was also strongly associated with overall survival, cancer risk, cardiovascular disease, and other major health outcomes. At that point, it became clear that we weren't just discovering a new cancer biomarker, we were uncovering a much broader measure of adult immune health."

But what is it about the thymus that may have such a marked influence on people's health in adult life?

We don't know for sure, but the new findings echo a landmark study published in 2023, which discovered that people who had their thymus surgically removed faced an increased risk of death from any cause in the five years following their operation.

In contrast to the established view that the importance of the thymus diminishes with age, those findings supported "a role for the thymus contributing to new T-cell production in adulthood and to the maintenance of adult human health," the research team – led by Harvard University oncologist David Scadden – wrote in their paper.

The newer research arrives at a similar conclusion, suggesting that just because the thymus may shrink with age, that doesn't mean its gradual disappearance is a harmless vanishing act.

Aerts' team found that several lifestyle and health factors were linked to having poorer thymic health, including smoking, obesity, and chronic inflammation.

Putting it all together, it's suggestive of a two-way relationship.

A healthier thymus appears to help protect the body by producing better immune function through adulthood, but also inflammation, harmful habits, and disease can in turn hurt the organ, which may then proceed to weaken and shrink as people get older.

Those developments, once considered inevitable and normal, could instead be actionable – and longer, healthier lives may hang in the balance.

"I'm excited because this is more than the discovery of a new biomarker," Aerts said.

"It suggests that we've overlooked a major aspect of human biology for decades. If these findings continue to be confirmed, preserving and measuring immune health could become a new principle of medicine, much like we currently monitor heart or kidney function.

"The thymus may be one of the first organs that allows us to do that in a practical way."

The Life of Earth

https://chuckincardinal.blogspot.com/

'Natural Protection From Asthma And Allergies': Scientists Isolate Bacteria Behind The Immune System Farm Effect

02 August 2026, By J. Cockerill

https://www.sciencealert.com/natural-protection-from-asthma-and-allergies-scientists-isolate-bacteria-behind-the-immune-system-farm-effect

(Teerasak1988/iStock/Getty Images Plus)

For decades, scientists have theorized that kids actually need to get a bit dirty for their immune systems to develop fully.

It's known as the 'hygiene hypothesis'. And, as childhood rates of allergies, asthma, and hay fever rose drastically in industrialized Western nations, scientists noticed the same did not go for children raised on farms.

"Girls and boys who grow up on farms and are exposed to a wider variety of microbes have the problem far less often," says epidemiologist Markus Ege, of LMU University Hospital and the Institute of Asthma and Allergy Prevention at Helmholtz Munich in Germany.

That phenomenon is known as 'the farm effect'.

Now, Ege and his colleagues have found exactly which bacterial species mediate the farm effect in rural European children. This discovery goes some way towards verifying the hygiene hypothesis once and for all.

https://www.youtube.com/watch?v=n6jVWm7gsIU

Referring to the hygiene hypothesis, Ege says, "this kind of research can only show more or less convincing correlations."

"But with our new study, we can make a much stronger case," he continues, "because we can identify the individual links in the proposed causal chain: the bacteria, the relevant microbial metabolic products, and the human receptors."

Allergies, asthma, hay fever, and eczema: all of these conditions arise when the body's immune system unleashes an exaggerated immune response to harmless triggers.

If the hygiene hypothesis really has legs, scientists should be able to find specific microbes that, when humans are exposed to them, somehow give our immune systems the challenge they need to develop a more appropriate response, reducing the incidence of immune conditions.

In the new study, the researchers pointed the finger at nine suspect bacteria species.

"We identified a small number of bacteria, which we can now pinpoint down to the species level, such as Romboutsia timonensis and Glutamicibacter arilaitensis," explains bioinformatician Giulia Pagani, of Helmholtz Munich.

"These gram-positive bacteria together mediate two-thirds of the entire farm effect for asthma protection and half of the effect for hay fever and atopic eczema."

Cows could be your immune system's best friends. 

(Fly View Productions/E+/Getty Images)



The researchers discovered these species in dust samples collected from the mattresses of 1,018 rural South German schoolchildren, and the cow shed air at the farms of 47 of the kids.

The nine bacteria linked to the farm effect made up 6 percent of the relative abundance of microbes in mattress dust, but 25 percent in the cow shed samples.

Kids who were exposed to these microbes, and especially those who lived on farms, were much less likely to develop childhood asthma, in a classic example of the observed farm effect.

These microbes originate from the guts of cows, and then wind up in their poop, which may be how they become suspended in the air in cow sheds.

Farm kids spend time around cows, inhale the microbes, and, as their presence in mattress samples suggests, bring the microbes back into their homes where moderate exposure may continue.

That moderation is an important factor here, given the bacteria produce metabolites known to activate a receptor known as AhR, which triggers immune signaling and gene expression.

"High levels of AhR activation are detrimental, whereas moderate levels, as they may occur by inhalation of bacterial metabolites in cow sheds, are beneficial," the team writes.

When activated, AhR induces a strong anti-inflammatory response which may help prevent the development of asthma and allergies.

Scientists will need to conduct further experiments to determine the exact mechanisms by which these bacteria mediate the farm effect, since an observational study like this doesn't show that level of detail, and can't prove cause.

But the chain of events, from cow to bacteria to air to child's immune system, is finally coming into focus.

"Taken together, this analysis describes a strong and consistent association between specific environmental exposures and natural protection from asthma and allergies," the authors write.

"Broken down to a molecular level, these results may advance understanding of the mechanisms of asthma and allergy protection. Ultimately, this may foster the development of effective and well-tolerable prevention strategies for the most common chronic conditions in childhood."

The Life of Earth

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