Scientists describe a window into evolution before the tree of life

Oberlin College

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All life on Earth shares a common ancestor that lived roughly four billion years ago. This so-called “last universal common ancestor” represents the most ancient organism that researchers can study.

Previous research on the last universal common ancestor has found that all the characteristics we see in organisms today, like having a cell membrane and a DNA genome, were already present by the time of this ancestor. So, if we want to understand how these foundational characteristics of life first emerged, then we need to be able to study evolutionary history prior to the last universal common ancestor.

In a new article published in the journal Cell Genomics, scientists Aaron Goldman (Oberlin College), Greg Fournier (MIT), and Betül Kaçar (University of Wisconsin-Madison) describe a method to do just that. “While the last universal common ancestor is the most ancient organism we can study with evolutionary methods,” said Goldman, “some of the genes in its genome were much older.”  The authors describe a type of gene family known as a “universal paralog,” which provides evidence of evolutionary events that occurred before the last universal common ancestor.

A paralog is a gene family that has multiple members in the same genome. For example, in our own genome, we have eight versions of hemoglobin genes, which encode proteins that bind to oxygen and carry it through the blood. All of these paralog genes descended from an ancient globin gene that existed as a single copy about 800 million years ago. The paralogs were created by repeated duplications of that gene through DNA copying errors, with each copy then evolving its own distinct features over millions of years.

Universal paralogs are a rare, special type of paralog that have at least two copies in the genomes of all or nearly all organisms alive today. This broad presence indicates that the duplication of an original gene must have taken place before the last universal common ancestor, with multiple copies inherited by its descendants, all the way to the present day.

For this reason, the authors argue that universal paralogs provide an indispensable, but underutilized, target for understanding the earliest history of life on Earth, especially as tools for such research improve with the arrival of new AI-based techniques and AI-optimized hardware.

“While there are precious few universal paralogs that we know,” says Goldman, “they can give us a lot of information about what life was like before the time of the last universal common ancestor.” Fournier adds, “The history of these universal paralogs is the only information we will ever have about these earliest cellular lineages, and so we need to carefully extract as much knowledge as we can from them.”

In their article, Goldman, Fournier, and Kaçar, survey all known universal paralogs. These universal paralogs are all associated with the production of proteins or the movement of different molecules across cell membranes. These two features of the cell were therefore among the earliest characteristics of life to have evolved.

The authors also recommend deeper descriptions of the ancient ancestral genes themselves. For example, Goldman’s own lab at Oberlin studied a universal paralog family that is responsible for embedding enzymes and other proteins into cell membranes. Using common techniques of evolutionary biology and computational biology, they reconstructed the protein encoded by the original ancestor of this protein. They found that the simpler, ancient version of this protein was still able to perform functions like binding to the membrane and binding to the protein synthesis machinery, and could have assisted simple proteins in implanting themselves into an early cell membrane.

Ultimately, the authors hope that increasingly sophisticated computational tools will allow researchers to discover new universal paralog families and describe their ancient ancestors in greater detail. “By following universal paralogs,” says Kaçar, “we can connect the earliest steps of life on Earth to the tools of modern science. They provide us a chance to transform the deepest unknowns of evolution and biology into discoveries we can actually test”. They envision painting a more detailed picture of evolution prior to the last universal common ancestor, when life as we know it first emerged.

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Journal

Cell Genomics

DOI

10.1016/j.xgen.2026.101140 

Method of Research

Commentary/editorial

Subject of Research

Not applicable

Article Title

Universal Paralogs Provide a Window into Evolution before the Last Universal Common Ancestor

Article Publication Date

5-Feb-2026

 

Losing social connections can hurt wildlife populations

University of Colorado at Boulder

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Imagine an asteroid striking Earth and wiping out most of the human population. Even if some lucky people survived the impact, Homo sapiens might still face extinction, because the social networks humans rely on would collapse.

This dynamic also plays out in the wild.

Social interactions are essential for many animals, helping them to locate food, spot predators and raise offspring. Without such connections, individuals can struggle to survive.

In a new study, researchers at the University of Colorado Boulder challenge a long-held assumption that social connections matter most for “highly social species”, like humans and wolves. They show that much more common “loosely social species,” those that make temporary friends rather than living in stable groups, might be more vulnerable to extinction due to population declines that limit social interactions. Deer, squirrels, chickadees and a whole host of other animals, including invertebrates, all fall into this category.

The study was published in Trends in Ecology & Evolution.

“This finding comes at a moment when many wildlife populations are shrinking or fragmenting due to climate change, habitat loss and exploitation,” said senior author Michael Gil in the Department of Ecology and Evolutionary Biology in the College of Arts and Sciences. “We provide a new framework for predicting which species are most susceptible to collapse so we can better forecast risk.”

The extroverts

Nearly a century ago, American ecologist Warder Clyde Allee showed that animals often do better when they are in larger groups, a phenomenon known as an Allee effect. 

Studies have since linked larger group sizes to higher reproductive success and survival in many highly social animals, which are those that live in a fixed group. For example, meerkats with more group mates tend to have more offspring, and more of those offspring survive. 

Having more individuals in a group means the group members can get more help when needed, said Samantha Rothberg, the paper’s first author and a doctoral student in Gil’s lab in the Department of Ecology and Evolutionary Biology.  

“We can relate to that as humans, because we can benefit a lot from the information provided by individuals around us,” she added.  

While many explanations for Allee effects point to benefits from social interactions, research to date has failed to show that social behavior, or the loss of it, can tip a species’ chances of survival.

For example, in African wild dogs, larger packs often have more pups per animal. But when wild dog populations decline across the region, the remaining dogs form new social groups, allowing group sizes and overall survival rates to remain unchanged. 

Confused by the inconsistency, Rothberg, Gil and Ella Henry, another doctoral student in Gil’s lab, reviewed decades of ecological theory, models and case studies on social interactions and survival. 

What they found suggested that ecologists might have been looking at the wrong animals.

The introverts 

For decades, ecologists assumed that if social interactions are driving Allee effects, it would be the most pronounced in highly social species like meerkats and wild dogs. But those animals, Gil said, appear to have a built-in buffer against the loss of social interactions.

“It’s intuitive that we think the more social a species is, the more vulnerable it is to losing those interactions,” Gil said. But it turns out, highly social animals can actively compensate. 

Much like extroverted humans who have no trouble making friends when they move to a new city, wild dogs seek out new members to restore their group size when they lose members of their pack.  

Loosely social animals, by contrast, are more like introverted people. They make friends, but they don’t always have to hang out with them. These species don’t go out of their way to replace lost companions to maintain their social interactions. As a result, when their populations decline, they lose social benefits from experiencing fewer interactions.  

“When you remove individuals, you're not just removing those individuals from the population, you're also removing the benefits that they conferred on surviving individuals. That creates a feedback loop,” Rothberg said.

A driver of collapse

Gil said the study highlights a glaring possibility that more species are susceptible to population collapse than previously thought. 

According to the World Wildlife Fund, global wildlife populations have declined by at least 73% in the past 50 years. Many scientists have declared this period the “sixth mass extinction,” with human resource extraction wiping out species hundreds of times faster than they would otherwise disappear. 

“I’m looking out my window right now, and there are a couple of birds sitting on branches. They’re being social. But those moment-to-moment interactions are easy to take for granted. We now realize that, in aggregate, they can determine whether a population survives or collapses,” Gil said.
 

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Journal

Trends in Ecology & Evolution

DOI

10.1016/j.tree.2025.11.005 

 

Wolf reduction boosts caribou survival—but only in rugged terrain

More accessible landscapes see no improvement as other predators fill the gap

University of British Columbia

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image: 

Camera Trap Image of Female Caribou and Calf

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Credit: Cole Burton, UBC Forestry & Environmental Stewardship

Reducing wolves to protect endangered caribou doesn't always deliver the expected results—and the shape of the land may be the deciding factor.

That’s according to research led by doctoral student Tazarve Gharajehdaghipour and professor Dr. Cole Burton in UBC's faculty of forestry and environmental stewardship, which examined newborn caribou survival in Itcha Ilgachuz Park in west-central B.C.

Using GPS collars to track animals, the team found that B.C. wolf removals boosted calf survival in steep, mountainous terrain, but made no difference in flatter terrain.

"This study is a note of caution," said Dr. Burton. "Different herds face different conditions. Wolf control may not be reducing calf mortality as effectively as we once thought."

How land and predators affect calf survival

The key factor is which predators can catch calves at different ages. Bears and wolverines hunt newborn calves in the first two weeks, but can’t catch older, more mobile calves. Wolves, by contrast, can catch the older, faster calves.

In rugged areas, this makes a big difference. Bears and wolverines can kill newborns at high elevations, but by the time mother-calf pairs move down to valleys at around three weeks old, the calves are too fast to catch. At this stage, wolves become the main threat.

Before wolves were removed, most calf deaths occurred during this period. Removing wolves eliminated this later cause of death, boosting survival by 41 percentage points—because bears and wolverines cannot hunt the older calves effectively.

In more accessible areas, wolves can reach calving sites throughout the season, including early when calves are young and vulnerable. When wolves were removed, other predators, such as bears and wolverines, simply killed more of these young calves, so overall survival did not improve.

Tracking calves through mothers’ movements

This is the first study to use GPS collars to follow newborn mountain caribou survival. The research builds on tracking methods developed by co-author Dr. Marie Auger-Méthé, a UBC associate professor in the Institute for the Oceans and Fisheries and department of statistics.

They found clear patterns: mothers abruptly start moving less when giving birth to stay close to newborns, then gradually increase activity as calves get stronger, or quickly return to normal movement if a calf dies.

"This method lets us watch the critical first four weeks of life, when calves are most at risk. We also used camera traps to see when predators were on the calving grounds," said Gharajehdaghipour.

The caribou collar data, which this research paper is primarily based on, was collected by B.C. government biologists, and secured through open access. 

Conservation beyond predator control

The research also found that calf deaths before wolf reduction—likely caused by wolves—were linked to horseback and ATV trails and treed valleys. This suggests wolves use these areas to reach calves. Limiting trail development could help reduce wolf-caused deaths in places where wolf control isn’t used.

While B.C.'s wolf reduction program now covers 15 caribou herds, Dr. Burton emphasizes it’s critical to protect habitat.

"If wolf control is sometimes ineffective and diverts attention from habitat restoration, it's a real concern," he said. "Without recovering habitat, you'd have to keep controlling wolves indefinitely."

The researchers recommend that wildlife managers consider the landscape, predator communities, and habitat conditions before starting wolf control programs. They also encourage using GPS tracking and camera traps to better understand calf survival across B.C.

 

Camera Trap Image of Collared Female Caribou with Calf

Camera Trap Image of Caribou Calf

Credit

Cole Burton, UBC Forestry & Environmental Stewardship

Tazarve Gharajehdaghipour (IMAGE)

University of British Columbia

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Tazarve Gharajehdaghipour

Journal

The Journal of Wildlife Management

DOI

10.1002/jwmg.70143 

Method of Research

Observational study

Subject of Research

Animals

Article Title

Neonate mortality in mountain caribou: Patterns of predation during onset of a wolf reduction program