They've got to get out there and eat as much as they can of everything
In the permafrost of Canada's Yukon, the humble burrows of arctic ground squirrels have yielded something extraordinary: a genetic archive spanning nearly 700,000 years, preserved by ice and the industrious hoarding habits of creatures that slept through history. Researchers at McMaster University, sifting through ancient feces and frozen debris, recovered DNA from woolly mammoths, wolves, horses, and hundreds of plant species — a reminder that nature's most faithful record-keepers are rarely the ones we expect. The discovery invites us to reconsider where the past hides, and how much of life's story remains locked in the cold, waiting for the right question to unlock it.
- A team hunting for squirrel microbiome data stumbled instead onto one of the richest ancient DNA archives ever found, spanning nearly a million years of biological history.
- The sheer diversity of recovered genetic material — six woolly mammoth genomes across different eras, plus wolves, bison, horses, a cheetah, and hundreds of plants — has upended assumptions about where ancient DNA can be found and preserved.
- Permafrost-sealed burrows acted as accidental time capsules, with the squirrels' own hoarding and hibernation behavior doing the preservation work that no laboratory could have engineered.
- The data is being made publicly available, feeding directly into de-extinction efforts like Colossal's woolly mammoth project, though scientists caution that a resurrected animal may be more engineered approximation than true revival.
- A follow-up study promising to reframe the woolly mammoth's evolutionary history is already in the pipeline, suggesting this frozen archive has not yet given up all its secrets.
In the frozen ground of Canada's Yukon, scientists have uncovered a genetic archive spanning nearly 700,000 years — and it came from an unlikely source: the preserved feces of arctic ground squirrels, sealed inside their burrows since the last ice age. The discovery, led by paleogenomics researcher Tyler Murchie at McMaster University, contains DNA from woolly mammoths, wolves, bison, horses, a cheetah, and hundreds of plant species. Murchie acknowledged that excavating ancient squirrel droppings lacks the romance of unearthing a mammoth tusk, yet the volume and diversity of what his team found suggests that feces represents a profoundly overlooked window into Earth's distant past.
The squirrels proved to be nature's perfect archivists, though not by design. During their brief four-month active season, they frantically pack their burrows with everything they can find — seeds, bones, fur, scraps — before hibernating. Over millennia, rising permafrost sealed some burrows entirely, creating perfectly preserved time capsules. In one case, a squirrel was found frozen mid-sleep, having never awakened from its final hibernation.
What began as a microbiome study became something far larger. Using computational methods to reconstruct fragmented DNA, the team assembled 18 mitochondrial genomes, including sequences from six woolly mammoths across different eras — a rare chance to trace how an extinct species evolved over hundreds of thousands of years. The data will be made publicly available, offering a resource for de-extinction projects like Colossal's woolly mammoth initiative, though skeptics note that any resurrected animal would likely resemble a genetically modified Asian elephant more than a true mammoth.
Published in Nature Communications, the research also points toward a forthcoming study on mammoth evolutionary history that Murchie described only as "super cool." For now, the discovery stands as a quiet testament to the idea that the most profound scientific insights often emerge from the most unexpected places.
In the frozen ground of Canada's Yukon territory, scientists have stumbled onto an archive of life that spans nearly a million years—and it came from an unlikely source: the feces of arctic ground squirrels sealed inside their burrows since the last ice age.
The discovery, announced this week by researchers at McMaster University, contains genetic material stretching back between 3,000 and 700,000 years. Among the DNA fragments recovered are samples from woolly mammoths, wolves, bison, horses, a cheetah, and hundreds of plant species. Tyler Murchie, the paleogenomics researcher who led the study, acknowledged that excavating ancient squirrel droppings might lack the romance of unearthing a mammoth tusk. Yet what his team found inside those burrows—the sheer volume and diversity of preserved genetic information—suggests that feces represents an overlooked window into Earth's distant past.
The squirrels themselves turned out to be nature's perfect archivists, though not by design. Arctic ground squirrels spend only about four months each year awake, hibernating through the rest. During their brief active season, they frantically gather everything they can find—nuts, seeds, leaves, bones, fur, and scraps—and pack it into their burrows for the long sleep ahead. Over millennia, rising permafrost sealed some of these burrows completely, transforming them into perfectly preserved time capsules. Murchie described finding one squirrel frozen in its burrow, having gone to sleep one season and never awakened, preserved until a paleontologist discovered it thousands of years later.
The research team had initially set out simply to study the squirrels' microbiome. Instead, they encountered what Murchie called a "really surprising biodiversity of organisms." Using computational methods to stitch together fragmented DNA like puzzle pieces, the scientists reconstructed 18 mitochondrial genomes, including genetic sequences from six woolly mammoths that lived in different eras. This genetic material now offers researchers a rare opportunity to trace how these extinct species evolved across hundreds of thousands of years.
The findings have immediate relevance for de-extinction efforts. Colossal, a U.S. company, has publicly committed to resurrecting the woolly mammoth, which vanished roughly 4,000 years ago. Murchie's team plans to make their genetic data publicly available for such projects. However, he noted that Colossal already possesses extensive DNA sequences from multiple organisms, so the new material represents only a modest addition to their existing archive. Skeptics have questioned whether any resurrected animal would truly be a mammoth at all, arguing it would more closely resemble an Asian elephant with genetic modifications designed to mimic mammoth traits.
The research, published in Nature Communications, opens a second avenue of investigation. Murchie hinted at an upcoming study that will use the recovered DNA to illuminate the woolly mammoth's evolutionary history, though he declined to elaborate beyond calling it "super cool." For now, the discovery stands as a reminder that the most profound scientific insights sometimes emerge from the most unexpected places—in this case, from the preserved waste of small rodents that survived the ice age by sleeping through most of it.
Notable Quotes
They've got to get out there and eat as much as they can of everything— Tyler Murchie, McMaster University paleogenomics researcher, explaining why squirrels are ideal subjects for this research
I can't believe that we were able to get these insights from squirrel feces— Tyler Murchie
The Hearth Conversation Another angle on the story
So you're telling me scientists found DNA from extinct animals in squirrel poop. How does that even work?
The squirrels weren't just leaving droppings—they were packing their burrows with everything they could find during their four months awake each year. Bones, fur, plant material, all of it. When permafrost sealed those burrows, it created a frozen time capsule that preserved everything inside, including the DNA.
And this DNA is how old?
Between 3,000 and 700,000 years old. The oldest material gives us a window into ecosystems that existed during the ice age itself.
Why squirrels specifically? Why not just dig up mammoth bones?
Because squirrels are natural collectors. They gather indiscriminately—they're not selective. So their burrows contain a cross-section of what was living around them. You get mammoths, yes, but also wolves, bison, horses, plants. It's a biodiversity snapshot.
The de-extinction angle—does this actually help bring mammoths back?
It provides genetic reference material, but the researchers are careful not to oversell it. The company trying to resurrect mammoths already has extensive DNA. This is useful, but it's not the breakthrough that makes it suddenly possible.
What surprised the scientists most?
That they found this at all. They went in expecting to study the squirrels' own microbiome. Instead they discovered an entire archive of ancient life, preserved by accident through hibernation and permafrost.