- Rebecca Morel
- Science Editor, BBC
The oldest-ever DNA sequence has revealed what the Arctic was like two million years ago, when the region had higher temperatures.
Today this area in northern Greenland is considered a polar desert, but genetic material extracted from the soil reveals a rich variety of plants and animals.
Scientists found genetic traces of an elephant-like mastodon, reindeer, geese that roamed among the birch and poplar trees, and marine life, including horseshoe crabs and algae.
Publication of the research in the journal nature.
Professor Esk Willerslev, who conducted the study and is a researcher at the University of Copenhagen and the University of Cambridge, noted that This mixture of arctic and temperate species that lived together has no modern equivalent.
The research was conducted in an area called the Kap København Formation, which is located in the far north of Greenland.
Until now, it was difficult to go back in time and understand what this region was like two million years ago.
Fossils of animals from this period are extremely rare in the studied area.
“In fact, in Kapp Copenhaven, the only animals that have been discovered through macrofossils are the hare’s tooth and the dung beetle. So people had no idea what kind of animals were there at that time,” explained Professor Willerslev.
Instead, the researchers turned to Environmental DNA studyeDNA in English. It is genetic material shed from plants and animals, for example from skin cells or droppings, and accumulates in their environment.
It is a technique widely used in preservation today. For example, DNA in a drop of ocean water can reveal which organisms lived in that environment, even if individual animals could not be seen.
In Greenland, the team used ancient soil samples to look back in time and study the biology of the early Ice Age.
Scientists have found a forest ecosystem, where arctic shrubs, grasses, ferns and mosses grow among the trees.
In addition to finding DNA from creatures such as rodents, reindeer, and geese, The discovery of mastodon DNA was a surprise. Willerslev told the BBC that no one had ever found elephant-like creatures in Greenland.
Two million years ago, northern Greenland was much warmer than it is now. Average annual temperatures were between 11 and 19 degrees Celsius higher than today.
What this work really tells us is that Plasticity of living organismsIn terms of where they can live and which plants or animals can live together, it’s much larger than we thought.”
Extracting DNA from soil and sequencing it wasn’t easy: it took the team years to find the best technology to do it. Scientists even thought that it would not be possible for genetic material to survive for so long..
“I wrote an article in 2005 where I said I thought DNA wouldn’t live for more than a million years, and here we are with DNA that’s two million years old,” Willerslev told the BBC.
The researcher believes that a chemical reaction between DNA and soil is slower than the decomposition of genetic material.
“DNA is made of electrically charged particles, and many of the minerals that we see in the Earth also have an electrical charge. So the DNA will basically bind to solid minerals, and when that happens, it will automatically slow down the rate of decomposition,” he said.
If more environmental DNA is found at other sites, studying it could change the way we look at the ancient world.
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