While northern Greenland may be a polar desert today, two million years ago it hosted a diverse range of plant and animal life.
Using the oldest DNA ever analyzed, a team of scientists discovered that a number of animals, including mastodons, reindeer, geese and hares, used to live in the area, as well as a range of tree species. “No one would have predicted an ecosystem like this. Some species you find further south in Greenland, but a number you don’t find in the Arctic at all,” says Eske Willerslev, a paleogeneticist at the University of Cambridge and a co-author of the study, to Science’s Richard Stone. “It’s an ecosystem with no analog in the present day.”
“It’s a tour de force. Simply astounding,” Ross MacPhee, a paleontologist at the American Museum of Natural History who did not contribute to the research, says of the work to Science.
In 2006, the researchers visited northern Greenland’s Kap Kobenhavn Formation. The scientists gathered frozen dirt from the 100 meter-thick sediment deposit, writes Nature News’ Ewen Callaway, that they hoped would contain information about the region’s history, per National Geographic’s Alejandra Borunda. The team would comb through the samples for environmental DNA (eDNA)– DNA organisms leave in the environment by secreting it as waste or shedding it as skin or hair, for example.
But tools available ten years ago weren’t advanced enough to analyze the DNA, according to National Geographic. As DNA ages, it breaks into miniscule bits that are hard to study, per Maddie Burakoff of the Associated Press (AP). The team tried to read the DNA, but “we failed and failed and failed,” Willerslev tells Science.
Technology eventually caught up with the scientists’ aspirations, as co-author Karina Sand, a geochemist at the University of Copenhagen in Denmark, and colleagues learned to free DNA stuck to minerals in the sediment. In the end, the researchers discovered more than 100 types of plants and nine types of animals that lived in the region at the time, per the Washington Post's Kasha Patel. Beyond evidence of reindeer, geese and one mastodon, they also found signs of marine species, including horseshoe crabs and green algae. In this era of the island's geologic history, temperatures were around 18 to 31 degrees Fahrenheit warmer than they are in Greenland today.
“I wouldn’t have, in a million years, expected to find mastodons in northern Greenland,” Love Dalen, a paleogeneticist at Stockholm University in Sweden who didn’t contribute to the research, tells the AP. The plants included shrubs and birch trees that still live in Greenland today, but also poplar, spruce and yew trees that are only found further south.
“It feels almost magical to be able to infer such a complete picture of an ancient ecosystem from tiny fragments of preserved DNA,” Beth Shapiro, an evolutionary biologist at the University of California, Santa Cruz who did not contribute to the work, told National Geographic via email.The findings also show the benefits of eDNA. “You really get a broader picture of the ecosystem at a particular time,” Benjamin Vernot, an ancient DNA researcher at the Max Planck Institute for Evolutionary Anthropology in Germany who did not contribute to the study, tells the AP. “You don’t have to go and find this piece of wood to study this plant, and this bone to study this mammoth.”