Ancient squirrel feces offer ‘time capsule’ of environment thousands of years ago
DNA from 700,000-year-old squirrel feces in the Yukon reveals the diet and environment of the Pleistocene epoch. According to researcher Tyler Murchie in Nature Communications, these organic samples identify a landscape of grasses and herbs inhabited by woolly mammoths, extinct bison, and horses.
How does ancient squirrel DNA reveal Ice Age ecosystems?
Researchers use “palaeogenomics” to extract genetic material from frozen droppings, which Tyler Murchie of the Hakai Institute describes as “little frozen time capsules.” Unlike dinosaur coprolites, which undergo mineral replacement, these samples remained organic because they were preserved in permafrost.
Murchie noted that the DNA resisted degradation despite the presence of digestive microbes. Once fluid is added to release the material, the organic nature of the scat becomes apparent—including a smell Murchie described as “overwhelming.”
What animals lived in the Klondike region 700,000 years ago?
The study, published Tuesday in Nature Communications, identified a diverse array of animal DNA within the pellets. Beyond the squirrels themselves, the genetic records show the presence of lemmings, pikas, caribou, snowshoe hares, and either wolves or coyotes.
The data suggests a scavenger diet. Murchie stated the squirrels likely fed on the carcasses of woolly mammoths, as well as extinct species of horse and bison. This points to a Pleistocene landscape dominated by flowering herbs and grasses, with very few trees and some woody vegetation.
For more on how ancient DNA is sequenced, visit the Nature Communications archive.
Why is the Yukon’s permafrost better for dating than Siberia’s?
Precise dating is often the hardest part of palaeogenomics. Murchie explained that the ancient squirrel burrows in the Yukon are preserved in layers of volcanic ash. This geological marker allows scientists to establish more exact age estimates than those possible at similar sites in Siberia.
This precision helps researchers map out exactly when certain species disappeared or migrated as the climate shifted. It transforms a general estimate into a concrete timeline of biological change.
What can these findings tell us about modern climate change?
The goal is to understand “interglacial periods”—stretches of time between ice ages when the earth warmed. Murchie is specifically focused on the last interglacial period, approximately 115,000 years ago, when temperatures were higher than they are today.
By comparing that period to the current epoch (the Holocene), researchers hope to determine if human-caused climate change has permanently broken the natural glacial-interglacial cycle. Murchie warned that the melting permafrost is currently destroying the very samples that provide these insights.
Frequently Asked Questions
How old are the squirrel droppings?
The samples date from between 17,000 and 700,000 years ago.
Why was the DNA still preserved?
The samples were frozen perpetually in permafrost and protected within burrows, preventing the usual organic decay.
What did the Ice Age squirrels eat?
Their diet included plants and the scavenged remains of woolly mammoths, extinct horses, and extinct bison.
Who led the research?
Tyler Murchie of the Hakai Institute served as the lead author of the study.
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