Scientists have recovered the oldest DNA sample to date, making a major breakthrough in genetic research. 2-million-year-old DNA offers an unprecedented look at a unique Ice Age ecosystem and offers a glimpse into our own future in a warming world, new research suggests.
This discovery is based on environmental DNA (eDNA), a mixture of genetic material that represents an entire environment for life. It is obtained from the Kap København Formation, a fossil layer located in the polar desert in Northern Greenland. The frozen landscape and mineral conditions at the site helped preserve this genetic material, which is a full million years older than the next oldest DNA found in a mammoth tooth.
Since 2006, researchers led by Eske Willerslev, an evolutionary geneticist at the University of Cambridge, have been painstakingly collecting and analyzing samples from Kap København. Now the team presents a “reconstructed ecosystem that has no modern counterpart.” It was home to mastodons, reindeer, geese, horseshoe crabs, corals and other life forms that lived around an open boreal forest that thrived when this part of Greenland was 11-19C warmer than today, according to the study, published in the Nature journal.
There is one notable omission from this study: predators. Although no traces of predators were found in the eDNA samples, Willerslev’s team suggested that this was simply because predator populations tend to be much smaller than herbivore populations, leading to a sampling bias.
“We believe it’s basically a numbers game,” Willerslev said. “The environmental DNA is really reflecting the biomass of the organisms. The more biomass you have, the more DNA is left in the surroundings. Therefore, obviously plants are more common than herbivores, and herbivores are more common than carnivores, so that’s probably the reason why we’re not capturing the carnivores.”
Mikkel Pedersen, a geogeneticist at the University of Copenhagen who co-authored the study, suggests that bears, wolves or even saber-toothed tigers might have existed in this ancient habitat, based on modern North American ecosystems. However, he emphasized that this is only speculation, and there is currently no solid evidence of any predators at Kap København.
So the researchers are eager to continue collecting and analyzing samples from the site to track down more extinct creatures that lived there two million years ago. Willerslev said he would not be surprised to find eDNA that is twice as old as the Kap København samples, potentially pushing the ancient DNA timeline back four million years.
This study of our past is also a window into our future, as climate change is likely to produce some of the same conditions that existed two million years ago. The mastodons, reindeer and crabs of this northern ecosystem lived long before modern man, but we now live in a world that has been fundamentally changed by our own species and its activities.