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Two million-year-old DNA found in Greenland

Published on Sunday, December 11, 2022 at 07:00

Various DNA fragments found in Ice Age sediments in Greenland are the oldest ever extracted. They are a million years older than the previous record of DNA extracted from a Siberian mammoth bone.

It’s a major discovery for paleogenetics: Two million-year-old DNA has been found in Greenland, scientists announced this week, making it the oldest ever sampled.

“DNA can survive for 2 million years, twice as old as previously discovered DNA”explains AFP Mikkel Winther Pedersen, one of the lead authors of the study published in the journal Science Nature.

The different DNA fragments identified in the sediments “come from the northern tip of Greenland, called Cape Copenhagen, and from an environment that we don’t see anywhere on Earth today,” he says.

They are very well preserved because they are frozen and found in areas that have not been heavily exploited, the University of Copenhagen lecturer continues.

“The rivers (accepted) the minerals and organic matter in the marine environment, and these land deposits were deposited. Then, at some point, about 2 million years ago, this land beneath the water was uplifted and became part of northern Greenland.” He says.

Mastodons, Reindeer and Rabbits

Cape Copenhagen today is an arctic desert. A wide variety of deposits have already been discovered there, including the best-preserved fossils of plants and insects. The researchers did not try to establish the DNA of the discovered elements and there was very little information about the existence of animals.

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The researchers’ work, which began in 2006, has made it possible to paint a portrait of the region 2 million years ago. “We had this forest environment with mastodons, reindeer and hares and a huge number of different plant species. We saw 102 different plant species,” said Mr. Winter Pedersen notes. According to him, the presence of the mastodon is particularly significant, as it has never been noted so far north. At these latitudes, the sun never sets during the summer months, as two million years ago Greenland — Danish for “green land” — experienced temperatures 11 to 17 degrees warmer than today. It rises in winter.

“Nowhere else on Earth today do we see the connection of these species,” said the paleo-ecologist. It “makes us think about species plasticity: how species actually adapt to a climate, to different types of climates, may be different than we previously thought.”

“We break the barrier of what we think we can achieve”

Thanks to innovative technology, the researchers discovered that the 41 fragments examined were millions of years older than the previous record of DNA extracted from Siberian mammoth bones. It is important to determine if the DNA is hidden in the clay and quartz so that it can then be separated from the sediment for analysis.

The method used “provides a fundamental understanding of why minerals or sediments can protect DNA… It’s a Pandora’s box we’re about to open,” explains Karina Sand, who led the geology group at the University of Copenhagen and participated in the study. .

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Mr. For Winter Pedersen, with this discovery, “we are breaking the barrier of what we thought we could achieve in terms of genetic studies”. “One million years was long thought to be the limit for DNA survival, but today we’re doubling that. And that drives us to look for bases.”, he adds. “There are many different sites around the world that have geological deposits that go back a long way. And even further back in time,” the researcher says.