Discovery of two-million-year-old DNA doubles previous age record and opens up new era, says University of Cambridge scientist

DNA that is two million years old has been identified for the first time – and it is twice the age of any previously discovered.

The startling find opens a new chapter in our understanding of evolution and presents “endless” possibilities for scientists.

The microscopic fragments of environmental DNA were found in Ice Age sediment in northern Greenland and cutting-edge technology was used to confirm they are one million years older than the previous record for DNA, which had been sampled from a Siberian mammoth bone.

The researchers have used the DNA to map an ancient ecosystem that weathered extreme climate change and they hope their findings could help us predict the long-term impact of what is happening now.

It represents another triumph for Prof Eske Willerslev, a fellow of St John’s College at the University of Cambridge and director of the Lundbeck Foundation GeoGenetics Centre at the University of Copenhagen, who led the research with the geology expert Prof Kurt H Kjær, who is also based at the centre in Denmark. They found evidence of animals, plants and microorganisms including reindeer, hares, lemmings, birch and poplar trees.

Prof Willerslev said: “A new chapter spanning one million extra years of history has finally been opened and for the first time we can look directly at the DNA of a past ecosystem that far back in time.

“DNA can degrade quickly but we’ve shown that under the right circumstances, we can now go back further in time than anyone could have dared imagine.”

They even found that the Ice Age mammal Mastodo roamed as far as Greenland before it became extinct, overturning previous thinking that these elephant-like animals did not extend as far from their known origins of North and Central America.

Prof Kjær said: “The ancient DNA samples were found buried deep in sediment that had built up over 20,000 years. The sediment was eventually preserved in ice or permafrost and, crucially, not disturbed by humans for two million years.”

The results of the 41 usable samples found hidden in clay and quartz in this extraordinary time capsule have now published in Nature. The samples were incomplete and just a few millionths of a millimetre long.

They were taken from the København Formation, a sediment deposit that built up in a shallow bay to almost 100 metres thick in the mouth of a fjord in the Arctic Ocean, at Greenland’s northernmost point.

At the time, the climate in Greenland varied between Arctic and temperate – and was 10-17C warmer than the country is today.

It took painstaking detective work by 40 researchers from Denmark, the UK, France, Sweden, Norway, the USA and Germany to unlock the secrets of the DNA. First, they established that there was DNA hidden in the clay and quartz and then worked out if they could extract it. Eventually, they could and they were able to compare every single DNA fragment with extensive libraries of DNA from present-day animals, plants and microorganisms to build up a picture of the genetic information from trees, bushes, birds, animals and microorganisms.

While some DNA fragments were predecessors to present-day species and therefore simple to classify, others could only be linked at genus level. Some originated from species that are impossible to place in the DNA libraries of animals, plants and microorganisms alive today, meaning researchers will build up a picture of an unknown stage in evolution.

Prof Kjær said: “Expeditions are expensive and many of the samples were taken back in 2006 when the team were in Greenland for another project. They have been stored ever since. It wasn’t until a new generation of DNA extraction and sequencing equipment was developed that we’ve been able to locate and identify extremely small and damaged fragments of DNA in the sediment samples.”

Asst Prof Mikkel W Pedersen, co-first author on the paper and also based at the Lundbeck Foundation GeoGenetics Centre, said: “The data suggests that more species can evolve and adapt to wildly varying temperatures than previously thought. But, crucially, these results show they need time to do this. The speed of today’s global warming means organisms and species do not have that time so the climate emergency remains a huge threat to biodiversity and the world.”

The researchers also found DNA from microorganisms, including bacteria and fungi, which they are continuing to map. They plan a further research paper explaining the biological interaction between animals, plants and single-cell organisms in the former ecosystem.

It could be that lessons from the survival of two-million-year-old plant DNA could help us understand how endangered species could become more resistant to a warming climate.

Prof Kjær said: “It is possible that genetic engineering could mimic the strategy developed by plants and trees two million years ago to survive in a climate characterised by rising temperatures and prevent the extinction of some species, plants and trees. It could reveal how to attempt to counteract the devastating impact of global warming.”

The findings from the Kap København Formation in Greenland represent what the team says is a new age of DNA detection.

Prof Willerslev, who previously led a study showing climate change caused the extinction of woolly mammoths, said: “Now that we have successfully extracted ancient DNA from clay and quartz, it may be possible that clay may have preserved ancient DNA in warm, humid environments in sites found in Africa.

“If we can begin to explore ancient DNA in clay grains from Africa, we may be able to gather ground-breaking information about the origin of many different species – perhaps even new knowledge about the first humans and their ancestors – the possibilities are endless.”