The discovery of the world’s oldest DNA, dating back two million years, could reveal how to fight global warming, scientists have said.
Opening what has been hailed as a “revolutionary” new chapter in evolutionary history, microscopic fragments have been discovered buried deep in sediments that had accumulated over more than 20,000 years in northern Greenland.
It allowed DNA to survive despite extreme climate change and broke the previous record – samples taken from a Siberian mammoth bone – by a million years.
The newly discovered samples, incomplete and a few millionths of a millimeter long, come from a period when Greenland’s climate varied between arctic and temperate and was 10-17°C warmer than today.
They were found in the Kobenhavn Formation, a sediment deposit almost 100 meters thick nestled in the mouth of a fjord in the Arctic Ocean.
Scientists have found evidence of plants, microorganisms and animals – including lemmings, reindeer, hares and the elephant-like mastodon (the Ice Age mammal, not the social media platform).
Professor Eske Willerslev, who led the team, said: “DNA can degrade quickly, but we have shown that under the right circumstances we can now go back further in time than anyone would have dared. to imagine.”
How were the secrets of DNA discovered?
Forty-one of the Ice Age samples discovered were usable for scientists’ research.
They had to be detached from the clay and quartz in which they were buried, having been preserved by ice or permafrost and – importantly – undisturbed by humans.
Detective work by dozens of researchers spanning Denmark, the UK, the US, France, Sweden, Norway and Germany eventually led to the samples being compared with extensive DNA libraries from current organizations.
This is how they were able to find evidence of predecessors of species we know today, building a picture of a previously unknown stage in the evolution of many species that still exist.
Some samples had been taken in 2006 during a previous expedition, but only new equipment developed over the years allowed the DNA to be extracted.
Could the findings help save species from climate change?
The survival of DNA through changing environmental conditions is the most striking feature of the discovery.
Assistant Professor Mikkel W Pedersen said there is “no current equivalent” for the historical ecosystem whose DNA can be traced back.
He added: “At first glance, the climate appears to have been similar to the climate we expect on our planet in the future due to global warming.”
Professor Pedersen continued: “The data suggests that more species can evolve and adapt to wildly variable temperatures than previously thought.
“But, above all, these results show that they need time to do so.
“The speed of global warming today means that organisms and species don’t have that time, so the climate emergency remains a huge threat to biodiversity and the world.”
‘The possibilities are limitless’
Professor Kurt H Kjaer, a geology expert at the University of Copenhagen, said genetic engineering could be the key to mimicking the strategy that allowed plants and trees two million years ago to survive in the middle. of rising temperatures.
“That’s one of the reasons why this scientific breakthrough is so important – because it could reveal how to try to counter the devastating impact of global warming,” he added.
The next step could be to explore potentially rich deposits of ancient DNA in hot, humid environments.
Professor Willerslev described the possibilities as “endless”.
“If we can start exploring the ancient DNA of clay grains from Africa, we may be able to gather groundbreaking information about the origin of many different species,” he said.
“Maybe even new insights into early humans and their ancestors.”
The results were published in the journal Nature.
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