Two million-year-old NA from northern Greenland pushed the genetic record back 1 million years, to a time when the Arctic region was 50-65 degrees warmer and home to abundant wildlife – including mastodon, lemmings and geese.
According to researchers from the University of Cambridge and the University of Copenhagen, Greenland’s northern peninsula – now a polar desert – once contained boreal forests of poplar and birch that teemed with wildlife.
“A new chapter covering an additional 1 million years of history has finally opened and for the first time we can directly see the DNA of a past ecosystem this far back in time,” said researcher Professor Eske Willerslev, adding: “DNA can degrade quickly, but we’ve shown that under the right conditions, we can now go further back in time than anyone would dare to imagine.”
Willerslev added that similar techniques could one day be used to uncover information about early humans and their ancestors.
Willerslev and his colleagues worked for 16 years on the project, which resulted in the sequencing and identification of the DNA of 41 samples found hidden in clay and quartz. The ancient DNA samples were found buried deep in the Kap København Formation, a sediment deposit nearly 100 meters thick that accumulated over 20,000 years. The sediment, hidden at the mouth of a fjord in the Arctic Ocean at the northernmost point of Greenland, was eventually preserved in ice or permafrost and remained undisturbed by humans for 2 million years.
Extracting and analyzing the DNA was a painstaking process that involved assembling tiny fragments of genetic material, which first had to be separated from the clay and quartz sediment. Only the advent of a new generation of DNA sequencing techniques has enabled scientists to locate and assemble extremely small and damaged pieces of DNA by reference to extensive DNA libraries collected from present-day animals, plants and microorganisms.
Once they put the pieces together, a picture emerged of forests teeming with reindeer, rabbits, lemmings, and mastodons—the latter of which had previously only been found in North and Central America.
No carnivores were found, probably because they were fewer in number, but the researchers hypothesized that there were probably ancient sauro-toothed tigers, wolves or bears.
“The data suggest that more species can evolve and adapt to wildly changing temperatures than previously thought,” said Dr. Mikkel Pedersen, of the Lundbeck Foundation Center for Geogenetics at the University of Copenhagen and an author.
