Two million-year-old DNA from northern Greenland has revealed that the region was once home to mastodons, lemmings and geese, providing an unprecedented insight into how climate change can shape ecosystems.
Advances in ancient DNA analysis push the DNA record back 1 million years to a time when the Arctic region was 11-19°C warmer than today. The analysis reveals that the northern Greenland Peninsula, now a polar desert, once featured boreal forests of poplar and birch teeming with wildlife. The work offers clues as to how species might adapt, or be genetically modified, to survive the threat of rapid global warming.
Professor Eske Willerslev, from the University of Cambridge and the University of Copenhagen, said: “A new chapter spanning another 1 million years of history has finally opened, and for the first time we can look directly at the DNA from a past ecosystem long ago. time.”
The fragments are 1 million years older than the previous record of DNA collected from a Siberian mammoth bone. “DNA can degrade quickly, but we’ve shown that under the right circumstances, we can now go back in time beyond what anyone could have imagined,” said Willerslev.
In the future, similar techniques could be used to uncover new insights into early humans and their ancestors, he added.
Willerslev and his colleagues worked for 16 years on the project, which resulted in sequencing and identifying 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 in 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 gathering small fragments of genetic material that first had to be separated from the clay and quartz sediment. It was only the advent of a new generation of DNA sequencing techniques that allowed scientists to identify and assemble extremely small and damaged fragments of DNA, by referencing extensive DNA libraries collected from animals, plants and current microorganisms.
A picture emerged of forests populated by reindeer, hares, lemmings and mastodons, elephant-like Ice Age mammals previously found only in North and Central America.
The samples did not reveal any carnivores, probably because they were fewer in number, but scientists speculated that there could be ancient bears, wolves or saber-toothed tigers. “We don’t know what was in it, but probably something that ate mastodons and reindeer,” Willerslev said.
The authors say it is encouraging that these species were able to thrive this far north in a region that would still have been darkened for much of the winter, despite warmer temperatures.
“The data suggest that more species can evolve and adapt to highly variable temperatures than previously thought,” said Dr. Mikkel Pedersen of the Center for Geogenetics at the Lundbeck Foundation at the University of Copenhagen and co-first author.
However, the speed of current global warming means that many species will not have enough time to adapt, meaning that the climate emergency remains a major threat to biodiversity. Willerslev and his colleagues said studying ancient ecosystems could provide clues about how some species genetically adapted to a warmer climate.
“It is possible that genetic engineering could mimic the strategy developed by plants and trees 2 million years ago to survive in a climate characterized by rising temperatures and avoid the extinction of some species, plants and trees,” said Professor Kurt Kjærr of the University of Copenhagen and a co-author. “That’s one of the reasons why this scientific breakthrough is so significant because it could reveal how to try to counter the devastating impact of global warming.”
The findings are published in the journal Nature.