Ancient DNA from Squirrel Poop Reveals Ice Age Ecosystem
A groundbreaking study published in Nature Communications has uncovered a treasure trove of ancient environmental DNA (aeDNA) from frozen ground squirrel feces, offering a remarkably detailed snapshot of life in the Arctic thousands of years ago.
"These droppings preserve more detailed genetic snapshots of ancient Beringia than bones or surrounding permafrost."
The DNA, extracted from coprolites (frozen feces) of Arctic ground squirrels (Urocitellus parryii) in Canada's Yukon territory, dates back between 3,000 and 700,000 years. The material was preserved in sealed burrows, offering a unique time capsule of the ancient ecosystem.
Key Genetic Discoveries
Researchers reconstructed over 18 mitochondrial genomes from the samples. The identified animal species paint a picture of a vibrant Ice Age landscape:
- Woolly mammoths (six genomes from different time periods)
- Horses
- Steppe bison
- Grey wolves
- A big cat (identified as either a cougar or an American cheetah)
- Hares, lemmings, birds, and other ground squirrels
In addition to animal life, the team recovered plant DNA from grasses, sedges, willow, buttercups, and over 200 other plant groups, representing the ancient mammoth steppe ecosystem that once dominated the region.
What the Squirrels Ate
The analysis reveals that ancient Arctic ground squirrels were opportunistic omnivores. While they primarily ate vegetation, they also consumed meat. This behavior is consistent with modern Arctic ground squirrels, which occasionally eat insects, carrion, and meat—particularly around hibernation.
A 700,000-Year-Old Mystery
The research also uncovered a previously unknown lineage of Arctic ground squirrel dating back 700,000 years. Relatives of this lineage now live only in western Siberia—not in the Yukon, suggesting major shifts in species distribution over time.
Preservation and Scientific Significance
Arctic ground squirrels line their burrows with food and debris during the summer. When these burrows become sealed and frozen by permafrost, the contents—including fecal matter—are remarkably well preserved.
Lead author Tyler Murchie, a paleogenomics researcher at McMaster University, noted that these droppings provide more detailed genetic snapshots than bones or surrounding permafrost.
Data Access and Future Research
The genetic data will be made publicly available. Murchie indicated this would include access for Colossal, a company working on woolly mammoth de-extinction, though he noted the company already possesses extensive genomic data.
McMaster University and the Hakai Institute were awarded $2.3 million for a separate study investigating how landscapes recovered from past climatic shifts, with the goal of predicting ecosystem responses to current warming. The research team is also conducting a separate analysis of what the DNA reveals about woolly mammoth evolution.
The research was conducted with permission from the Tr'ondëk Hwëch'in First Nation and involved scientists from McMaster University, the Hakai Institute, and the University of Alberta.