Scientists have identified DNA from animals, plants, and microbes from Greenland sediment dating back about 2 million years – the oldest on record by far – revealing an amazing lost world.
DNA fragments were found in a variety of animals, including mastodons, reindeer, hares, lemmings, and geese, as well as plants, including poplar, birch, and thuja trees, and microorganisms.
The samples were discovered in 2006, but previous DNA detection efforts were unsuccessful. Methods for extracting ancient DNA have since improved, allowing a breakthrough.
The majority of our knowledge about prehistoric organisms comes from studying fossils, but there is a limit to what these can reveal. That is where ancient DNA comes in handy.
Washington: Scientists have identified DNA from animals, plants, and microbes dating back about 2 million years from sediment dug up around the mouth of an Arctic Ocean fjord at Greenland’s northernmost point, revealing an amazing lost world at this remote frontier.
On Wednesday, researchers announced the discovery of DNA fragments from a variety of animals, including mastodons, reindeer, hares, lemmings, and geese, as well as plants such as poplar, birch, and thuja trees, and microorganisms such as bacteria and fungi. DNA is the self-replicating material in living organisms that carries genetic information – a kind of life blueprint.
The mastodon was an elephant relative that roamed North and Central America until its extinction around 10,000 years ago, along with many other large Ice Age mammals. The discovery demonstrates that it had a broader range than previously thought.
“The mastodon took me by surprise. It has never been discovered on Greenland before. “The greatest surprise was this unique ecosystem of Arctic and temperate species mixed together with no modern analogue,” said Eske Willerslev, director of the Lundbeck Foundation GeoGenetics Centre and lead author of the Nature study.
“I don’t think anyone would have predicted Greenland having such a diversity of plants and animals 2 million years ago, at a time when the climate was very similar to what we expect to see in a few years due to global warming,” Willerslev, who is affiliated with the Universities of Cambridge and Copenhagen, added.
Though ancient DNA is highly perishable, the study demonstrated that under the right conditions – in this case, permafrost – it can survive for much longer than previously thought. Willerslev stated that he would not be surprised to find DNA dating back at least 4 million years.
41 organic-rich sand samples were collected from five sites on the Peary Land peninsula that juts into the Arctic Ocean, and the researchers extracted and analysed the DNA from these samples. From the clay and quartz in the silt, microscopic DNA pieces were taken out. Over a hundred different species of animals and plants were identified.
The samples were discovered in 2006, but previous DNA detection efforts failed. Methods for extracting ancient DNA have since improved, allowing for a breakthrough.
“We believe it is because the DNA bound itself to mineral particles that it was able to survive beyond what was previously thought possible.” Willerslev claims that the bond “slows the rate of spontaneous chemical degradation.”
According to Willerslev, the fragmentary DNA cannot be used to resurrect extinct species, as in the Jurassic Park books and films, but it may reveal secrets about how plants can become more resistant to climate change.
The DNA remnants “cannot be used for cloning,” Willerslev said, “but they can be used to genetically modify living organisms such as plants to become more adapted to a warmer climate.”
Previous DNA was extracted from the molar of a mammoth, an elephant relative, in northeastern Siberia up to 1.2 million years ago, which was also preserved in permafrost conditions. In comparison, our species, Homo sapiens, evolved around 300,000 years ago.
The majority of our knowledge of prehistoric organisms comes from studying fossils, but there are limitations to what they can reveal, particularly in terms of genetic relationships and traits. This is where ancient DNA comes in handy.
The majority of modern Greenland is covered by ice, with ice-free areas along the coast. The study area is classified as a polar desert. According to study first author Kurt Kjaer of the University of Copenhagen, Greenland’s average temperatures were 20-30° F (11-17° C) higher 2 million years ago.
The presence of marine species such as horseshoe crab and green algae among the DNA detected demonstrated the warmer climate, according to the researchers.
The DNA has revealed this ancient ecosystem in great detail, with an open boreal forest teeming with animals and featuring trees, shrubs, and smaller plants. According to study co-author Mikkel Pedersen of the University of Copenhagen, the large predators present may have included wolves, bears, and sabre-toothed cats.
According to study co-author Nicolaj Larsen of the University of Copenhagen, the researchers are looking for even older DNA in northern Canada.
“I believe you can find such long-term DNA survival in many places around the world,” Willerslev said. “It’s just getting out there and trying.”
(Reuters)
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