DNA from 2 million years in the past is the oldest ever recovered

DNA certain to mineral particles in historical sediment reveals that north Greenland as soon as had spruce forests populated by hares, reindeer and even mastodons

By Michael Marshall

DNA from 2 million years in the past recovered from sediments in Greenland is the oldest preserved DNA discovered thus far, blowing previous the earlier benchmark of 1 million years set in 2021.

“The age of the DNA is twice as old approximately compared to what has been retrieved previously,” says Eske Willerslev on the College of Cambridge.

The DNA comes from a number of various organisms, enabling Willerslev and his colleagues to reconstruct the ecosystem that existed in northern Greenland 2 million years in the past, at a time when the local weather was hotter than it’s right now. Right this moment, the world is Arctic desert and has few organisms, however again then it was a forest inhabited by hares, reindeer and maybe even mastodons, elephant-like animals that when lived in North America.

The discover means that will probably be potential to uncover DNA from rather more historical time intervals than beforehand suspected. “I wouldn’t be surprised if it turned out that in the north [the Arctic], we could go twice as far back in time,” says Willerslev.

He and his crew obtained historical DNA from the Kap København Formation, a collection of layers of sand, silt and dirt greater than 90 metres thick in complete. These have been laid down 2 million years in the past.

The DNA didn’t come from fossilised organisms, however was as an alternative certain to mineral particles within the sediment layers. This helped protect the DNA, as a result of enzymes couldn’t get to it to interrupt it down, says crew member Karina Sand on the College of Copenhagen in Denmark.

This environmental DNA got here from the entire vary of organisms dwelling within the space. The crew detected 102 genera of vegetation. Some nonetheless develop in northern Greenland right now, just like the shrubs Dryas and Vaccinium. However others now not dwell there, like spruce (Picea) timber, hawthorn (Crataegus) and Populus flowers. “It is, in fact, a forest,” says Willerslev.

Fewer animal species have been recognized, most likely as a result of they at all times make up much less of the biomass than vegetation, says Willerslev. Nonetheless, the DNA revealed Arctic hares (Lepus arcticus), rodents associated to lemmings and muskrats, geese and reindeer.

There was additionally DNA from an extinct elephant relative, which the crew tentatively recognized as a mastodon, not a mammoth. Mastodons lived within the Americas for a number of million years, however hadn’t beforehand been present in Greenland. It isn’t identified how mastodons might need travelled to Greenland, however they might have crossed sea ice.

If free-floating DNA can survive this lengthy by binding to mineral particles in chilly situations, it suggests there may be actually historical DNA to be discovered, says Laura Parducci at Sapienza College of Rome in Italy, who wasn’t concerned within the analysis.

The Kap København Formation existed early within the Pleistocene Epoch, which started 2.58 million years in the past and ended 11,700 years in the past. At first of the Pleistocene, everlasting ice lined the north pole for the primary time in thousands and thousands of years, and it has remained frozen ever since. Moreover, the Arctic was chilly even earlier than the Pleistocene, so there may be some permafrost that’s even older – with DNA preserved in it.

Nevertheless, Antarctica froze over a lot earlier, starting round 35 million years in the past, says Parducci. “So potentially there you can go much deeper in time.” Nevertheless, “the diversity of the plants and animals would be far less”, says Kurt Kjaer on the College of Copenhagen, one of many examine authors, as a result of Antarctica has been polar desert for therefore lengthy.

Journal reference: Nature, DOI: 10.1038/s41586-022-05453-y