In a study spanning meerkats in the Kalahari desert, coatis in Panama’s rainforest, and spotted hyenas in Kenya’s savanna, researchers have discovered that the daily actions of these animals show surprisingly similar patterns. Whether a meerkat scratches in the sand for scorpions or a coati rests in the canopy, a shared ordering of the behaviors persists across different landscapes, species, individuals, and types of behaviors. To the international team of fourteen authors, led by researchers at the Max Planck Institute of Animal Behavior, the findings are unexpected and — possibly — profound.

“We assumed there would be differences,” said Pranav Minasandra, a postdoctoral researcher at MPI-AB and lead author of the study in PNAS. After all, differences are apparent when comparing meerkats, coatis, and hyenas, which occupy dissimilar environments and ecological roles. “But we found common patterns in how animals switch between behaviors, regardless of what species and which individual. It’s as if their behavior was built on the same hidden algorithm.”

Uncovering underlying patterns

The hidden algorithm came to light in data that were collected from wild animals tagged with accelerometers — the same small sensors in phones and watches that track our activity. The species studied are all social mammals, but they differ in their ecology and behavior. Spotted hyenas are large carnivores, meerkats are small burrowing animals, and coatis are racoon-sized tree-dwellers. Accelerometers measure posture changes many times each second and the recordings can continue for several days. These high-resolution motion traces collected from animals were then classified using machine learning into behavioral states like lying, foraging, and walking. For instance, a meerkat might lie down for 10 minutes then briefly stand up to look around for 20 seconds before moving around to search for food for another few minutes.

“This approach allowed us to capture detailed behavioral sequences over days and even weeks from multiple individuals across three distinct species,” says Ariana Strandburg-Peshkin, group leader at MPI-AB and senior author on the study.

Across behaviors, individuals, and species, one common principle emerged: the longer an animal stays in one behavioral state, the less likely it is to change it in the next moment. “This was unexpected,” adds Minasandra.

Imagine a hyena walking continuously for 10 minutes. Most people would probably guess that the hyena would be more likely to stop over time, and the authors did too. “We originally thought the probability of switching behaviors would increase over time, as we assumed it would not be optimal to lock-in to any behavior.” Remarkably, this kind of lock-in, also called a decreasing hazard function, was consistent across all studied animals and species.

The authors further examined how current behavior predicts future actions — a concept they call “predictivity decay.” Predictivity decay reflects the increasing difficulty in predicting behavior the further we look into the future, primarily due to random, unpredictable variations. The shape of the decay graph conveys how decision-making systems across different timescales interact to generate animals’ behavioral sequences. “We found that the pattern of predictivity decay was remarkably consistent across all animals studied, implying a shared architecture beneath the surface.”

Why these patterns?

The study raises a big question: Why do such patterns occur? The authors propose two broad explanations.

First is positive feedback: the longer an animal remains in a state — say, lying down — the more likely that staying put is rewarded, whether because it’s warm, safe, or socially reinforced. Behavior becomes self-reinforcing.

The second possibility is multi-timescale decision-making. Instead of a single internal clock governing when to switch behaviors, animals may integrate cues from many processes — internal hunger, external threats, social context — each with its own tempo. The interplay of these overlapping signals could generate the observed patterns.

Future studies may explore whether these patterns hold in other animals beyond the three mammals in the study: non-social species, across developmental stages, or under different ecological pressures. There’s also the question of whether these long-time behaviors offer advantages — perhaps by optimizing attention, conserving energy, or enhancing group coordination.

Says co-author Meg Crofoot, Director of the Department for the Ecology of Animal Societies: “What this study suggests is that real animals, be they hunting, hiding, or resting, are guided by hidden structures that seem to echo across life’s branches.”

“Methane is a very potent greenhouse gas that we need to address urgently,” said co-author Xin (Lindsay) Lan, a climate scientist at CU Boulder’s Cooperative Institute for Research in Environmental Sciences (CIRES). “Our study suggests that a significant portion of the recent rise in atmospheric methane originates from natural sources driven by climate change. Our emission reduction efforts need to be more aggressive.”

Methane is the second most abundant human-produced greenhouse gas after carbon dioxide. But an equal amount of methane traps about 30 times more heat than CO₂ over a 100-year time frame. Methane has been responsible for roughly a quarter of the planet’s warming since the Industrial Revolution.

Lan has spent the past decade tracking methane concentrations in the atmosphere at Boulder’s Global Monitoring Laboratory at the National Oceanic and Atmospheric Administration (NOAA).

Lan and her colleagues at NOAA have observed a rapid increase in atmospheric methane levels in recent years. While previous studies have shown fossil fuel production accounts for 30% of global methane emissions, Lan and colleagues have noticed a steady increase in emissions from microbial sources since 2007.

These microbes, specifically a group known as archaea, produce methane as a byproduct of their metabolism in environments like wetlands, landfills and livestock’s digestive systems.

Together, microbial emissions contribute to nearly half of global methane emissions, but it remains unclear which specific sources are driving this increase.

“While long-term methane trends are important to investigate, we also need to look at seasonal variations to understand how individual sources are changing and how the natural mechanisms that remove methane from the atmosphere are evolving,” Lan said.

A vicious cycle

To get a clearer picture, Lan and her team analyzed seasonal fluctuations in atmospheric methane levels over the past four decades.

They found that methane’s seasonal amplitude — the difference between peak and lowest methane levels within a year — has been decreasing in northern high-latitude regions, including the Arctic.

Using computer models, the team showed that this trend since the 1980s is largely a result of increased methane emissions from wetlands. Increased precipitation in the Arctic has expanded the region’s wetlands by 25% during the warmer months. Rising temperatures have also been melting some of the perpetually frozen soil layer deep underground, known as permafrost, in summer.

The melted, waterlogged soils have provided ideal conditions for archaea to thrive, leading to higher methane emissions which in turn could accelerate warming further.

Scientists have long warned about such climate feedback loops, but the precise scale and speed of these effects remain uncertain. Lan said this new study added another piece of evidence that natural methane emissions have already been responding to a warming climate.

“This study, along with a few previous studies, has provided indirect evidence on potential climate feedback on methane emissions, which would be beyond our ability to control directly,” Lan said.

The sharp increase in atmospheric methane and its climate feedback effects since 2007 resemble the planet’s most dramatic warming events that brought past ice ages to an end, according to Lan’s previous research.

“Our hope is that by rapidly reducing emissions, we can avoid triggering more severe and abrupt climate feedback that could lead to catastrophic events,” she said.

Methane sponges

The team’s simulations also found a 10% increase in the levels of hydroxyl (OH) radical since 1984. These radicals are highly reactive molecules that can soak up and remove methane and other air pollutants.

Because these molecules stay in the air for less than a second before they react with other compounds, scientists cannot directly measure them globally. In the past, researchers had assumed the OH levels remained constant over the years when calculating atmospheric methane emissions, but this study suggested that assumption might be wrong.

“Our result showed that we’ve been underestimating how much methane the atmosphere has been removing, which means that there’s actually more methane being emitted than we previously estimated,” Lan said.

Understanding the specific source of emission is vital in designing climate mitigation policies. While microbial emissions are responsible for most of the methane growth, human-produced methane from burning fossil fuels remains an important contributor.

“We need to aggressively cut all greenhouse gas emissions from the sources we can control,” Lan said. She added that the world’s permafrost currently holds at least twice as much carbon as is currently in the atmosphere. If future warming causes widespread permafrost thaw and releases that carbon, it could trigger irreversible changes to the planet’s climate. “We need to address the feedback loop before reaching that tipping point.”

Humans perceive and navigate the world around us with the help of our five senses: sight, hearing, touch, taste and smell. And while scientists have long known that these different senses activate different parts of the brain, a new Yale-led study indicates that multiple senses all stimulate a critical region deep in the brain that controls consciousness.

The study, published May 15 in the journal NeuroImage, sheds new light on how sensory perception works in the brain and may fuel the development of therapies to treat disorders involving attention, arousal, and consciousness

In the study, a research team led by Yale’s Aya Khalaf focused on the workings of subcortical arousal systems, brain structure networks that play a crucial role in regulating sleep-wake states. Previous studies on patients with disorders of consciousness — such as coma or epilepsy — have confirmed the influence of these systems on states of consciousness.

But prior research has been largely limited to tracking individual senses. For the new study, researchers asked if stimuli from multiple senses share the same subcortical arousal networks. They also looked at how shifts in a subject’s attention might affect these networks.

For the study, researchers analyzed fMRI (functional magnetic resonance imaging) datasets collected from 1,561 healthy adult participants as they performed 11 different tasks using four senses: vision, audition, taste, and touch.

They made two important discoveries: that sensory input does make use of shared subcortical systems and, more surprisingly, that all input — regardless of which sense delivered the signal — stimulates activity in two deep brain regions, the midbrain reticular formation and the central thalamus, when a subject is sharply focused on the senses.

The key to stimulating the critical central brain regions, they found, were the sudden shifts in attention demanded by the tasks.

“We were expecting to find activity on shared networks, but when we saw all the senses light up the same central brain regions while a test subject was focusing, it was really astonishing,” said Khalaf, a postdoctoral associate in neurology at Yale School of Medicine and lead author of the study.

The discovery highlighted how key these central brain regions are in regulating not only disorders of consciousness, but also conditions that impact attention and focus, such as attention deficit hyperactivity disorder. This finding could lead to better targeted medications and brain stimulation techniques for patients.

“This has also given us insights into how things work normally in the brain,” said senior author Hal Blumenfeld, the Mark Loughridge and Michele Williams Professor of Neurology who is also a professor in neuroscience and neurosurgery and director of the Yale Clinical Neuroscience Imaging Center. “It’s really a step forward in our understanding of awareness and consciousness.”

Looking across senses, this is the first time researchers have seen a result like this, said Khalaf, who is also part of Blumenfeld’s lab.

“It tells us how important this brain region is and what it could mean in efforts to restore consciousness,” she said.

Other authors include Erick Lopez, a former undergraduate researcher in Blumenfeld’s lab, and collaborators from Harvard Medical School.

This research was supported in part by funding from the National Institutes of Health.