“Oldest Known DNA Paints Picture of a Once-Lush Arctic: In Greenland’s Permafrost, Scientists Discovered Two-Million-Year-Old Genetic Material from Scores of Plant and Animal Species, including Mastodons, Geese, Lemmings and Ants”, 2022-12-07 (; backlinks):
…the samples, described on Wednesday in the journal Nature, came from more than 135 different species. Together, they show that a region just 600 miles from the North Pole was once covered by a forest of poplar and birch trees inhabited by mastodons. The forests were also home to caribou and Arctic hares. And the warm coastal waters were filled with horseshoe crabs, a species that today cannot be found any farther north of Maine.
Independent experts hailed the study as a major advance. “It feels almost magical to be able to infer such a complete picture of an ancient ecosystem from tiny fragments of preserved DNA”, said Beth Shapiro, a paleogeneticist at the University of California, Santa Cruz. “I think it’s going to blow people’s minds”, said Andrew Christ, a geoscientist at the University of Vermont who studies the ancient Arctic. “It certainly did so for me.”
The discovery came after two decades of scientific gambles and frustrating setback.
…The researchers dug up permafrost and brought it back to Copenhagen to search for DNA. They failed to find any. In later years, Dr. Willerslev and his colleagues had more success when they examined younger sediments and bones from other parts of the world. They discovered a wealth of ancient human DNA that has helped reshape our understanding of our species’ history. Along the way, the researchers tweaked their methods for extracting DNA from ancient samples and upgraded the machines they used to sequence it. As they became better at fishing for genes, they would take out more of the Kap Kobenhavn samples for another shot.
But for years they failed, again and again. From time to time they were tantalized by what looked like short bits of DNA, which are called ‘reads’. The researchers couldn’t rule out the possibility that bits of young DNA in Greenland, or even in their lab, had contaminated the reads. Finally, after a major upgrade in their technology, they found DNA in the samples in 2017. The permafrost turned out to be loaded with genetic material. Before long they had collected millions of DNA fragments. “It was a breakthrough”, Dr. Willerslev said. “It was going from nothing or very little that you don’t know is real, to suddenly: It’s there.”
…The researchers were surprised by some of the species they found. Caribou live today in Greenland, as they do across much of the Arctic. But until now, their fossil record suggested they evolved a million years ago. Their DNA now doubles their evolutionary history.
Love Dalén, a paleogeneticist from Stockholm University who last year discovered mammoth DNA in Siberia that was 1.2 million years old, marveled that mastodons turned up in Greenland. “What the hell are they doing up there?” he asked. Dr. Dalén noted that the nearest known mastodon fossils were 75,000-year-old remains in Nova Scotia—which are far younger than the Greenland DNA, and much farther south than Kap Kobenhavn. “You can’t go much further north on dry land”, he said.
…The scientists are also interested in how the DNA fragments managed to survive so long and defy expectations. Their research indicates that the DNA molecules can cling to minerals of feldspar and clay, which protect them from further damage. Based on that discovery, the researchers are developing new methods that they hope will let them pull even more DNA out of ancient sediments. Dr. Kjaer and his colleagues are scouting 4-million-year-old sites in Canada with the hope of breaking their own record. Dr. Dalén said they might succeed. But the damage that both he and the Danish researchers are finding in the oldest DNA suggests to him that it will be impossible to find ancient genetic material older than about 5 million years. “This in no way suggests that there will be any DNA coming out of dinosaur-aged fossils”, he said.