Thirteen frozen ground-squirrel pellets from Yukon yielded DNA that let researchers reconstruct ancient diets, habitats and squirrel lineages across roughly 700,000 to 17,000 years.
The oldest sample—nearly 700,000 years old—appears genetically distinct from modern Yukon squirrels and may represent a previously unknown species, pointing to a later population turnover.
Dietary DNA showed the squirrels ate widely, including grasses, willows, beetles and grasshoppers, plus traces from mammoths, bison, wolves and ancient horses—likely from scavenging or bone-chewing rather than hunting.
That omnivory turned the coprolites into ecosystem archives: the team reconstructed mitochondrial genomes from 24 animals, including 12 squirrels, two bison, three horses and six mammoths.
The pellets came from permafrost-preserved burrows exposed by Yukon gold mining, suggesting overlooked feces can capture richer Ice Age community snapshots than isolated bones alone.