A historic discovery that opens a new chapter for paleogenetics. Two-million-year-old DNA, the oldest ever extracted, has been unearthed from Ice Age sediments in Greenland, scientists said Wednesday. “DNA can survive for 2 million years, which is twice as old as previously found DNA,” says Mikkel Winther Pedersen, one of the study’s lead authors. 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 have been so well preserved because frozen and found in surfaces that have been little exploited, continues the lecturer at the University of Copenhagen.
Work started in 2006
“Rivers (carried) minerals and organic matter into the marine environment, where these terrestrial sediments were deposited. And then, at some point, about 2 million years ago, this underwater land mass was lifted up and became part of northern Greenland,” adds Mikkel Winther Pedersen. 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 lot of different plant species. We found 102 different plant taxa,” notes Mikkel 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”.
“A Pandora’s Box”
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 we’re about to open,” says Karina Sand, who leads the group. of geobiology at the University of Copenhagen and participated in the study.
For Mikkel 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 pushes 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.