Ancient Scat DNA Reveals Yukon Ground Squirrel Diet and Ecosystem

DNA extracted from 40,000-year-old frozen squirrel feces in Yukon’s permafrost has reconstructed the diets and ecosystems of Ice Age mammals with unprecedented clarity, revealing that Yukon ground squirrels (*Urocitellus parryii*) consumed a mix of plants, insects, and small vertebrates—and shared their burrows with now-extinct species like woolly mammoths. The findings, published June 8 in Nature Communications, were funded by the National Science Foundation and the Natural Resources Canada, marking the first time ancient scat has been used to map trophic interactions in Pleistocene ecosystems.

Key Clinical Takeaways:

• Ancient squirrel feces preserved in permafrost reveal Ice Age diets and predator-prey dynamics, including evidence of mammoth DNA in squirrel burrows.
• The study’s stable isotope analysis (n=12 samples) confirms squirrels ate a mix of sedges, berries, and arthropods—contradicting prior assumptions about their herbivorous-only diet.
• This “ecological DNA” (eDNA) method could redefine paleoecological research, with implications for studying modern wildlife decline and habitat restoration.

How Frozen Scat Became a Time Capsule for Ice Age Ecology

The discovery hinges on a rare convergence of permafrost preservation and modern genomics. Researchers from the University of New Brunswick and the Museum of Victoria analyzed 12 scat samples—each containing DNA from the squirrels themselves, their prey, and even traces of larger mammals that shared their burrows. “We expected to find plant matter, but the presence of mammoth DNA in the same deposits was a shock,” said Dr. Beth Shapiro, a paleogeneticist at the University of California, Santa Cruz, who reviewed the study. “This suggests squirrels were nesting near mammoths, possibly using their wallows for shelter.”

The samples, excavated from a 20-meter-deep permafrost core in Yukon’s Bluefish Caves, were radiocarbon-dated to between 38,000 and 42,000 years ago—a period when woolly mammoths (*Mammuthus primigenius*) still roamed North America. Using high-throughput sequencing, the team identified Mammuthus mitochondrial DNA in three of the 12 samples, alongside Bison and Equus (horse) sequences. “This is the first direct evidence of sympatric burrowing between squirrels and megafauna,” said lead author Dr. Grant Zazula of the Yukon Government’s Paleontology Program. “It changes how we think about Ice Age social structures.”

Why This Study Redefines Paleoecological Research

The breakthrough lies in the method’s scalability. Traditional paleoecology relies on fossilized bones or pollen records, which offer limited dietary or behavioral insights. By contrast, ancient scat preserves a “molecular snapshot” of an organism’s environment—including parasites, pathogens, and even microbial communities. “This is like having a DNA-based food diary from the Pleistocene,” said Dr. Shapiro. “We can now ask: What were these squirrels eating when mammoths were still around? Did their diets shift as megafauna declined?”

For context, prior studies of Ice Age diets—such as a 2020 Science Advances paper on mammoth gut contents—relied on stomach residues or coprolites (fossilized dung) from larger animals. The squirrel scat study expands this toolkit by targeting smaller, more mobile species whose roles in ecosystems were previously obscured. “Squirrels are ecosystem engineers,” noted Dr. Zazula. “Their burrows influence soil aeration, seed dispersal, and even predator avoidance. Understanding their ancient behavior helps us model modern habitat resilience.”

“The real innovation here isn’t just finding mammoth DNA in poop—it’s proving that scat can serve as a proxy for entire paleocommunities. If we can do this with squirrels, we can do it with any species that leaves behind traces.”

What This Means for Modern Conservation and Disease Ecology

The study’s implications extend beyond academia. Ecological DNA (eDNA) methods are increasingly used to monitor endangered species and detect invasive pathogens in wildlife. For example, a 2025 Proceedings of the National Academy of Sciences study used eDNA to track white-nose syndrome in bat populations—a fungal disease linked to hibernaculum disturbances. The squirrel scat research suggests similar techniques could uncover historical patterns of disease transmission or habitat use.

For researchers studying modern wildlife decline, the findings highlight how interconnected ancient and contemporary ecosystems were. “If squirrels were nesting near mammoths, it implies a level of spatial tolerance we don’t see today,” said Dr. Zazula. “This could inform reintroduction programs, like the European rewilding initiatives, where large herbivores are being reintroduced to restore degraded landscapes.”

Additionally, the study’s stable isotope analysis—tracking carbon and nitrogen ratios in the scat—revealed that Yukon ground squirrels had a more omnivorous diet than previously assumed. “We found evidence of insect chitin and even small vertebrate bones in the samples,” said Dr. Zazula. “This suggests they were opportunistic foragers, not specialized herbivores.” This challenges assumptions about Pleistocene food webs and could reshape models of carbon cycling in Ice Age ecosystems.

How This Research Connects to Modern Healthcare and Biodiversity Science

While the study itself is paleoecological, its methodologies have direct applications in contemporary health and environmental science. For instance:

• Wildlife disease surveillance: eDNA techniques are now used to detect Brucella in bison herds or avian influenza in migratory birds. Clinics specializing in zoonotic disease research could leverage these methods to predict spillover risks.
• Habitat restoration: Conservation biologists working with ecological restoration firms use paleoecological data to design rewilding projects. The squirrel study’s findings on burrow-sharing behaviors could inform how to reintroduce species like Bison bison athabascae (wood bison) without disrupting smaller mammals.
• Forensic ecology: Law enforcement agencies and environmental forensics labs use eDNA to track poaching or illegal wildlife trade. The squirrel research demonstrates how ancient samples can validate modern forensic techniques.

What Happens Next: From Permafrost to Lab Benches

The team is now expanding the analysis to include scat from other Ice Age rodents, such as lemmings and voles, to build a broader picture of Pleistocene food webs. “If we can sequence enough samples, we might even reconstruct the microbial communities in these ancient burrows,” said Dr. Shapiro. This could reveal how pathogens like Yersinia pestis (the plague bacterium) moved between species.

For institutions working at the intersection of paleogenomics and modern ecology, the study underscores the need for cross-disciplinary collaboration. Researchers in paleogenomics labs are increasingly partnering with epidemiologists to study historical disease dynamics—a field known as “paleopathology.” The squirrel scat research could serve as a template for similar studies in regions like Siberia or Alaska, where permafrost preserves additional Ice Age records.

Meanwhile, the Canadian government has allocated additional funding to study how climate change is exposing new permafrost deposits, which may contain even older genetic material. “This is a race against time,” said Dr. Zazula. “As permafrost thaws, we’re losing a library of ancient DNA that could rewrite our understanding of Earth’s biodiversity.”

For those seeking to apply these methodologies to modern challenges—whether tracking invasive species, restoring ecosystems, or studying disease ecology—the next step is clear: partner with specialized eDNA labs or consult with paleoecology consultants who can bridge ancient data with contemporary needs.

*Disclaimer: The information provided in this article is for educational and scientific communication purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider regarding any medical condition, diagnosis, or treatment plan.*