Orange ave Media Services, published on Sunday, December 11, 2022 at 07:00
The various DNA fragments discovered from ice age sediments in Greenland are the oldest ever extracted. They are a million years older than the previous record of DNA taken from a Siberian mammoth bone.
This is a major discovery for paleogenetics: DNA two million years old has been discovered in Greenland, scientists announced this week, explaining that it was the oldest ever extracted.
“DNA can survive for 2 million years, which is twice as old as previously found DNA”explains to AFP Mikkel Winther Pedersen, one of the main authors of the study published in the scientific journal Nature.
Identified in sediments, the different DNA fragments come “from the northernmost part of Greenland, called Cape Copenhagen, and (are) from an environment that we do not see anywhere on Earth today”, says- he.
They were so well preserved because frozen and found in areas that have been little exploited, continues the lecturer at the University of Copenhagen.
“Rivers (carried) minerals and organic matter into the marine environment, where these land sediments were deposited. And then, at some point, about 2 million years ago, this land mass beneath the water was uplifted and became part of North Greenland,” he says.
Mastodons, reindeer and hares
Cape Copenhagen is today an arctic desert. Different types of deposits, including excellently preserved fossils of plants and insects, had already been discovered there. The researchers had not sought to establish the DNA of the elements found and very little information existed on the possible presence of animals.
The work of the researchers, 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 with a large number of different plant species. We found 102 different plant taxa”, notes Mr. Winther Pedersen. According to him, the presence of mastodon is particularly notable because it had never before been noted so far north. Researchers are therefore reflecting on the adaptability of species because two million years ago Greenland – “green earth” in Danish – experienced temperatures 11 to 17 degrees higher than those of today but in these latitudes, the sun does not set in the summer months nor does it rise in the winter.
“We do not see this association of species anywhere else on Earth today,” said the specialist in paleo-ecology. This “makes you think about the plasticity of species: how species are actually able to adapt to a climate, to different types of climates, might be different from what we previously thought.”
“We break the barrier of what we thought we could achieve”
It was thanks to innovative technology that the researchers discovered that the 41 fragments studied are a million years older than the previous record of DNA taken from a Siberian mammoth bone. It was necessary to determine if DNA was hidden in the clay and the quartz and then that it was possible to detach it from the sediment to examine it.
The method used “provides a fundamental understanding of why minerals or sediments can preserve DNA… It’s a Pandora’s box that we are about to open”, explains Karina Sand, who directs the geobiology group at the University of Copenhagen and participated in the study.
For Mr. Winther Pedersen, with this discovery, “we are breaking the barrier of what we thought we could achieve in terms of genetic studies”. “It was long thought that a million years was the limit of DNA survival, but today we are double that. And obviously that drives us to look for sites”, he adds. “There are several different sites around the world that have geological deposits that go back that far. And even further back in time,” says the researcher.