Scientists Discover Oldest DNA Ever, Revealing 2 Million-Year-Old Lost World

In a major breakthrough for genetic research, scientists have recovered what is by far the oldest DNA to date. The 2-million-year-old DNA reveals an unprecedented glimpse of a unique Ice Age ecosystem that existed long ago, while also offering an eerie preview of our own future in a warming world, reports a new study.

The discovery of this lost world is based on environmental eDNA (eDNA), a mishmash of genetic detritus that represents an entire habitat, extracted from Kap København Formation, a fossil bed that sits in a polar desert in Northern Greenland. The frozen landscape and mineral conditions at the site contributed to the unrivaled preservation of 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 meticulously worked to collect and analyze samples from Kap København. Now, the team unveils a “reconstructed ecosystem [that] has no modern analogue,” home to mastodons, reindeer, geese, horseshoe crabs, corals, and other lifeforms that lived around an open boreal forest that flourished when this part of Greenland was 11 to 19°C warmer than it is today, according to a study published on Wednesday in Nature.

“It was super exciting when we recovered the DNA of a very different ecosystem,” Willerslev said in a press briefing on Tuesday that included several other study co-authors. “Obviously, it's important that we can go much further back in time, but it's also the time we can go back to. This is a time where it was significantly warmer” and featured “a climate which is very similar to what we expect to face with global warming.”

“Therefore, of course it gives some kind of idea or impression of how nature can respond to increasing temperatures,” he continued. “The great surprise is that this ecosystem that we see is an ecosystem with no modern analogue. It's a mixture between Arctic and temperate species and you don’t see that anywhere today.” 

If you were to travel back in time to Kap København two million years ago, you might see mastodons ambling along a coast forested by poplar, birch, and thuja trees. Perhaps you’d spot a river flowing out to the sea, carrying tiny bits of genetic material shed by the plants and animals along its banks, such as reindeer, geese, and rodents. Gazing out toward the ocean, you might catch a glimpse of horseshoe crabs scuttling through corals on the seafloor, or algal blooms forming on the waves.

This tantalizing vision has one notable omission: Carnivores. While no traces of predators were found in the eDNA samples, Willerslev’s team suggested that this was simply because carnivore populations tend to be far smaller than herbivore populations, producing a sampling bias.

“We believe it's basically a numbers game,” Willerslev told Motherboard during the briefing. “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.” 

“I would say, though, that if we continued taking and sequencing samples, my prediction would be that then we would catch, at some point, some of the carnivores,” he continued. “But at this stage, I'm afraid to say we don't really know what was up there—probably something that ate mastodons and reindeers.”

Mikkel Pedersen, a geogeneticist at the University of Copenhagen who co-authored the study, speculated to Motherboard that bears, wolves, or even saber-toothed tigers might have been present in this ancient habitat, based on contemporary North American ecosystems. However, he emphasized that this is only conjecture, and there’s no hard evidence of any carnivores at Kap København at this point.

To that point, the researchers are eager to continue collecting and analyzing samples from the site in order to track down more of the bygone creatures that thrived there two million years ago. The team also expressed hope that other frozen landscapes might contain these hidden genetic portals into long-lost biomes. Indeed, Willerslev said that he would not be surprised to find eDNA that is twice as old as the samples from Kap København, potentially pushing the timeline of ancient DNA back to four million years.

This exploration of our past is also a window into our future, as climate change is likely to produce some of the same conditions that were experienced two million years ago. The mastodons, reindeer, and crabs of this northern ecosystem lived long before the rise of modern humans, but now, we live in a world that has been fundamentally altered by our own species, and its activities.

“Nature has already experienced climate change,” Willerslev concluded. “By going back into the past, of course, you had this roadmap of how [species] adapted” which “opens up a new possibility if you want to try to mitigate the impact of climate change.”