A two-million-year-old DNA sample could provide a “groundbreaking” understanding of the world’s ancient ecosystems and how the environment may change as a result of the climate crisis.
The new sample, made up of microscopic fragments of environmental DNA, was found in Ice Age sediments in northern Greenland and is a million years older than the previous DNA record, which came from a Siberian mammoth bone.
The ancient DNA has already been used to map some of the components of a two-million-year-old ecosystem “that has withstood extreme climate change,” said the research team led by academics from Cambridge and Stockholm University.
They also believe the findings could help predict the long-term environmental toll of today’s global warming.
‘A new chapter covering a million more years of history has finally been opened and for the first time we can look directly at the DNA of a past ecosystem so far back in time,’ said St John’s College Fellow Professor Eske Willerslev , Cambridge, and who also works at Stockholm University.
“DNA can degrade rapidly, but we’ve shown that under the right circumstances, we can now go back in time further than anyone could have imagined.”
His colleague at Stockholm University’s Lundbeck Foundation GeoGenetics Centre, geology expert Professor Kurt Kjær, said the samples had been well protected from any human impact over the past two million years.
He said: ‘The ancient DNA samples were found buried deep in sediments that had accumulated over 20,000 years.
“The sediment was eventually preserved in ice or permafrost and importantly, it hasn’t been disturbed by humans for two million years.”
The researchers said the pieces of DNA they examined were incomplete samples, a few millionths of a millimeter long.
They were taken from an almost 100-meter-thick deposit of sediment known as the København Formation, which sits at the mouth of a fjord in the Arctic Ocean at the northernmost point of Greenland. Two million years ago the climate in Greenland ranged between arctic and temperate and was between 10 and 17°C warmer than Greenland is today. The sediment has built up meter by meter in a shallow bay.
The team said they also discovered evidence of microorganisms, animals and plants including reindeer, hares, lemmings, birches and poplars.
They also found that the mastodon, an elephant-like mammal from the Ice Age, roamed as far away as Greenland before going extinct thereafter. The mastodon’s range was previously thought not to extend as far north as northern Greenland from its known origins in North and Central America.
In order to carry out a comprehensive evaluation of the DNA fragments, 40 researchers from Denmark, the United Kingdom, France, Sweden, Norway, the United States and Germany worked on the samples.
“The process was painstaking,” the researchers said.
When they found the DNA, the researchers compared each individual piece of DNA with vast libraries of samples collected from today’s animals, plants and microorganisms.
“A DNA picture of trees, bushes, birds, animals and microorganisms began to emerge” from the world two million years ago.
They said some of the DNA fragments were easy to classify as ancestors of today’s species, while others could only be related at the genus level, and some came from species that are impossible to place in DNA libraries of still living animals, plants and microorganisms. in the 21st century.
The two-million-year-old samples have also helped academics build a picture of a previously unknown stage in the evolution of DNA from a number of species still existing today.
Professor Kjær said: ‘It was only when a new generation of DNA extraction and sequencing equipment was developed that we were able to locate and identify extremely small and damaged DNA fragments in the sediment samples. It meant we were finally able to map a two-million-year-old ecosystem.”
Assistant Professor Mikkel W Pedersen, co-first author of the paper and also based at the Lundbeck Foundation GeoGenetics Centre, said: ‘The Kap København ecosystem, which has no current equivalent, existed at considerably higher temperatures than the ones we have today – and why, 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.
“One of the key factors here is the extent to which species will be able to adapt to changing conditions resulting from a significant increase in temperature. The data suggests that more species may be evolving and adapting to wildly variable temperatures than previously thought. But most importantly, these results show that they need time to do it. The speed of today’s global warming means that organisms and species don’t have that time, so the climate emergency remains a huge threat to biodiversity and the world: extinction is on the horizon for some species, including plants and trees .
The research team said they believe some of the ‘tricks’ of discovered two-million-year-old plant DNA could be used to help make some endangered species more resilient to climate warming.
Professor Kjær said: ‘It is possible that genetic engineering could mimic the strategy plants and trees developed two million years ago to survive in a climate of rising temperatures and prevent the extinction of some species, plants and trees. . This is one of the reasons this scientific advance is so significant because it could reveal how we try to counteract the devastating impact of global warming.”
The Kap København clay findings could now open up a whole new period in DNA detection if scientists target similar geological formations.
Professor Willerslev explained: ‘DNA generally survives best in cold, dry conditions such as those prevailing during most of the period since the material was deposited at Kap København. Now that we have successfully extracted ancient DNA from clay and quartz, it is possible that the clay preserved ancient DNA in hot, humid environments at sites found in Africa.
“If we could start exploring the ancient DNA in clay grains from Africa, we might be able to glean groundbreaking information about the origin of many different species – perhaps even new knowledge about early humans and their ancestors – the possibilities are endless. “
The research is published in the journal Nature.