Field work conducted about a decade ago is changing researchers’ understanding of the extinction of large mammals during the Ice Age. Analysis of DNA trapped in frozen soil samples reveals that charismatic species such as woolly mammoths and wild Yukon horses survived longer than previously thought.
Soil samples were taken from the Klondike region in Yukon, Canada in early 2010, but no work has been published on them. Unlike traditional DNA samples, which can be taken from the bones or hair of an organism, soil (even the oldest) contains environmental DNA, which is genetic material trapped in the microscopic debris animals leave behind as they move through the environment.
The Klondike ice cores were later found in a refrigerator at McMaster University by Tyler Murchie, an archaeologist specializing in ancient DNA at the university, who set out to re-investigate them. The work of Murchi and her team is general ayer en Nature Communications.
“I found it in freezers while looking for a new project during my PhD,” Murchie, lead author of the new 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 tried to understand was the conditions under which the great North American species became extinct in the last Ice Age. Animals such as woolly mammoths, bison and wild horses roamed the continent for thousands of years, but the first two disappeared from the planet. (Modern horses are directly related to Ice Age horses.)
Lo que mató a los animales generalmente se atribuye a una de dos cosas: un Clima Kaleido That wiped out their food sources or poaching by mankind. The Recent Research They generally aim for the former.
“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.
The team found in ancient permafrost DNA evidence that large mammal species were not doing well even before climate change. In other words, the abundance of DNA in the samples began to decline long before climatic changes. (The team used radiocarbon dating of plant materials in soil samples to determine their ages.) But the animals did not disappear quickly. Woolly mammoths and North American horse DNA remained in samples until only 5,000 years ago, in the mid-Holocene, about 8,000 years after the animals were believed to be extinct.
“The data provide a unique window into the dynamics of megafauna and differentiate discussion of their extinction through more precise reconstructions of past ecosystems,” said Hendrik Poinar, an evolutionary geneticist at McMaster University and lead author of the research paper. release academic.
In fact it is, but this information is disappearing. As the climate warms, this time at an alarming rate for human causes, permafrost is losing its permanence. Large puddles appear in the northern reaches of the planet, causing swaths of land to collapse Huge basins. The thaw also threatens genetic information that was stored cold in the frozen ground. However, at the same time, the loss of permafrost has led to some startling discoveries as the preserved remnants of ice have appeared, including Cave lion cub Still hairy and 30,000 year old wolf head.
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