2.4 million year old DNA is the oldest ever recovered

DNA fragments recovered from an ice cap in northern Greenland represent the oldest DNA ever found, a group of Danish scientists report today (7 December) in Nature. The team dates the samples to around 2.4 million years ago, making the sequenced DNA almost twice the age of the Previously oldest DNAwhich was recovered from a Siberian mammoth bone.

“It’s a tour de force. Simply amazing, ”says Ross MacPhee, a paleontologist at the American Museum of Natural History who was not involved in the work. Science.

A combination of the site’s soil composition and falling temperatures from the Ice Age that began about 2.5 million years ago preserved the DNA, study co-author Karina Sand said. , geochemist at the Center for Geogenetics of the Lundbeck Foundation at the University of Copenhagen. Science. The trick to getting sequences from such ancient samples was revised extraction protocols, the outlet explains, which allowed the team to extract ancient DNA from quartz and clay in the sediments.

Ancient DNA fragments found in the ice sheet came from more than 135 different species, according to The New York Times. DNA fragments taken from the environment are known as environmental DNA or eDNA and are often used to monitor the presence and abundance of species in modern ecosystems. Danish scientists used the ancient fragments to do the same, analyzing DNA to determine what species were in the 2.4 million year old ecosystem.

See “Is global warming harming megafauna?”

Researchers have found DNA from traditional inhabitants of the Arctic such as reindeer, lemmings and Arctic hares. But to their surprise, they also found modern species that no longer exist in Greenland, and extinct species that wouldn’t normally be associated with the region. Among the modern species detected were poplars and birches as well as horseshoe crabs, none of which still live this far north. “No one would have predicted an ecosystem like this,” said Eske Willerslev, a paleogeneticist at the University of Cambridge who led the study. Science. “It is an ecosystem without analog at present.”

One of the most surprising discoveries is the discovery of DNA from an undocumented branch of mastodons, Love Dalén, a paleogeneticist from Stockholm University who was not involved in the research, tells the Time. Previously, he says, the mastodon DNA found closest to the Greenland site was located much further south in Canada and was much younger at just 75,000 years old.

See “Mastodons in motion”

“It’s 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, who has no participated in the research. Time.

The findings are further confirmation of the value of eDNA and the vast potential of ancient DNA to unlock new insights into the prehistoric world, Willerslev said. Science. MacPhee agrees, telling the magazine that it’s now “possible to see a future in which what we now call paleontology takes place in a molecular biology lab.”