Science

Ice Age Mammoth and Horse DNA Found in Soil Samples Left in Freezer

Researchers collect a soil sample in the Canadian Yukon.

Researchers collect a soil sample in the Canadian Yukon.
Photo: Tyler Murchie

Field work conducted about a decade ago is only now changing researchers’ understanding of the major mammal extinctions during the Ice Age. Analysis of DNA trapped in frozen soil samples reveals that attractive species such as woolly mammoths and wild horses in the Yukon survived longer than previously thought.

Soil samples were taken from the Klondike region in the Canadian Yukon in early 2010, but no work has been published on them. Unlike traditional DNA samples, which may be taken from the bones or hair of some organisms, soil (even ancient ones) contains environmental DNA, which is genetic material sequestered in the remains of microscopic animals that they leave as they travel through the environment.

Cold Klondike cores were later found in a McMaster University freezer by Tyler Murchie, an archaeologist specializing in ancient DNA at the university, who set out to re-investigate them. It was the work of Murchi and his team published Today in Nature Communications.

“I found it in the freezers while looking for a new project during my PhD,” Murchie, lead author of the new research paper, said in an email. “One of my responsibilities at the Ancient DNA Center is freezer maintenance, so I had a pretty good idea of ​​the cool stuff that might be out there waiting for someone to study.”

One of the mysteries the team sought to understand was the conditions under which the large North American species became extinct in the last Ice Age. Animals such as woolly mammoths, steppe bison, and wild horses have ranged across the continent for thousands of years, but the former two have disappeared from the planet. (Modern horses are directly related to Ice Age horses.)

The killing of animals is usually attributed to one of two things: a Climate warming Wiping out their food sources, or poaching by the human race. Recent Research He generally referred to the former.

Mammoths, horses, and saber-toothed cats in an artist's illustration.

An artist’s imagination of the Pleistocene ecosystem.
clarification: Julius Csutouni

“I think a combination of climatic, environmental and human pressures best explains the losses, but more research is needed to solve that problem that Quaternary scientists have been grappling with for about 270 years,” Murchi said.

In DNA found in ancient permafrost, the team found evidence that large mammal species weren’t doing well even before climate change. In other words, the abundance of DNA in the samples began to diminish before the climatic shifts. (The team used radiocarbon dating of plant materials in soil samples to determine their ages.) But the animals did not disappear quickly. Woolly Mammoth and North Americaa horse DNA remains in the samples Until recently 5,000 years ago, in the middle of the Holocene, About 8000 years later than the animals were thought to be extinct.

Rich data provides a unique window into Megafau’s population dynamicsHendrik Poinar, an evolutionary geneticist at McMaster University and lead author of the research paper, said at one university release.

It really is, but this information is disappearing. As the climate warms, This time at an alarming rate for human reasons, permafrost loses its permanence. Vast puddles appear in the northern reaches of the planet, causing swaths of land to collapse huge sewers. Thawing also threatens genetic information stored cold in the frozen ground. At the same time, though, the loss of permafrost has led to some startling discoveries as the preserved remains emerged from the ice, including Still a furry cave lion cub and 30,000 year old wolf head.

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