Today, northern Greenland is an arctic wasteland. But genetic data mined from the soil has revealed a rich array of plants and animals that once made life in the region very different.
Scientists have found genetic traces of marine life, including elephant-like mammoths, caribou and geese, horseshoe crabs and algae roaming among birches and aspens.
The research was published in the journal Nature.
Professor Eske Willerslev, from the University of Copenhagen and the University of Cambridge, who led the research, said this blend, in which arctic and temperate species coexist side by side, has no analogues in modern times.
SAMPLES COLLECTED FROM A DELETED ENVIRONMENT IN GREENLAND
The research was conducted in an area called the Kap København Formation in the northernmost part of Greenland.
So far it has been difficult to rewind time and understand what this region was like two million years ago. Animal fossils from this period are extremely rare here.
prof. “In fact, at Kap København, the only animals ever discovered through macro-sized fossils are the hare and the dung beetle. So people had no idea what kind of fauna there was at the time,” Willerslev said.
Instead, the team turned to environmental DNA (or eDNA). This means genetic material that is shed by plants and animals, such as skin cells or faeces, and accumulates in their environment.
This technique is now widely used in the protection of the natural environment. For example, examining DNA found in a drop of seawater can reveal all the creatures that lived in a part of the ocean, even if individual animals cannot be seen.
In Greenland, the team used ancient soil samples to examine the biology of the early ice age at the time.
They found a forest ecosystem filled with early Ice Age shrubs, grasses, ferns, and moss growing among the trees.
The discovery of DNA from living things such as rodents, reindeer and geese, as well as the discovery of DNA from mammoths, came as a surprise.
prof. Willerslev told the BBC that no one had ever found elephant-like animals in Greenland before.
Two million years ago, northern Greenland was much warmer than it is now. Mean annual temperatures were about 11-19°C higher.
prof. “What it really tells us is that the resilience of biological organisms — where they can live or which plants and animals can coexist — is much greater than we thought,” Willerslev said.
Extracting and sequencing DNA from the ground was not easy, and it took the team years to find the best technique to use. They also thought it might not be possible for genetic material to survive that long.
prof. “I wrote an article in 2005 and said in it that I didn’t think DNA could live longer than a million years, and here we have DNA that’s two million years old,” Willerslev said.
Think a chemical reaction between the DNA and the soil slows down the degradation.
“DNA is made up of electrically charged molecules, and many of the minerals we see in soil are also electrically charged. So DNA basically holds on to solid minerals, and when it does, it slows down the rate of spontaneous degradation.”
If more intact environmental DNA is found in other settlements, the discovery could change our view of centuries ago.
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