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DNA bound to mineral particles successful past sediment reveals that northbound Greenland erstwhile had spruce forests populated by hares, reindeer and adjacent mastodons
Life 7 December 2022Illustration of the past Greenland ecosystem Beth Zaiken/bethzaiken.com
DNA from 2 cardinal years agone recovered from sediments successful Greenland is the oldest preserved DNA recovered to date, blowing past the erstwhile benchmark of 1 cardinal years acceptable successful 2021.
“The property of the DNA is doubly arsenic aged astir compared to what has been retrieved previously,” says Eske Willerslev astatine the University of Cambridge.
The DNA comes from a big of antithetic organisms, enabling Willerslev and his colleagues to reconstruct the ecosystem that existed successful bluish Greenland 2 cardinal years ago, astatine a clip erstwhile the clime was warmer than it is today. Today, the country is Arctic godforsaken and has fewer organisms, but backmost past it was a wood inhabited by hares, reindeer and possibly adjacent mastodons, elephant-like animals that erstwhile lived successful North America.
The find suggests that it volition beryllium imaginable to uncover DNA from overmuch much past clip periods than antecedently suspected. “I wouldn’t beryllium amazed if it turned retired that successful the northbound [the Arctic], we could spell doubly arsenic acold backmost successful time,” says Willerslev.
He and his squad obtained ancient DNA from the Kap København Formation, a bid of layers of sand, silt and mud much than 90 metres heavy successful total. These were laid down 2 cardinal years ago.
Eske Willerslev and a workfellow illustration sediments successful Greenland for biology DNA Courtesy of NOVA, HHMI Tangled Bank Studios & Handful of Films
The DNA didn’t travel from fossilised organisms, but was alternatively bound to mineral particles successful the sediment layers. This helped sphere the DNA, due to the fact that enzymes couldn’t get to it to interruption it down, says squad subordinate Karina Sand astatine the University of Copenhagen successful Denmark.
This environmental DNA came from the full scope of organisms surviving successful the area. The squad detected 102 genera of plants. Some inactive turn successful bluish Greenland today, similar the shrubs Dryas and Vaccinium. But others nary longer unrecorded there, similar spruce (Picea) trees, hawthorn (Crataegus) and Populus flowers. “It is, successful fact, a forest,” says Willerslev.
Fewer carnal taxon were identified, astir apt due to the fact that they ever marque up little of the biomass than plants, says Willerslev. Nevertheless, the DNA revealed Arctic hares (Lepus arcticus), rodents related to lemmings and muskrats, geese and reindeer.
There was besides DNA from an extinct elephant relative, which the squad tentatively identified arsenic a mastodon, not a mammoth. Mastodons lived in the Americas for respective cardinal years, but hadn’t antecedently been recovered successful Greenland. It isn’t known however mastodons mightiness person travelled to Greenland, but they whitethorn person crossed oversea ice.
If free-floating DNA tin past this agelong by binding to mineral particles successful acold conditions, it suggests determination is genuinely past DNA to beryllium found, says Laura Parducci astatine Sapienza University of Rome successful Italy, who wasn’t progressive successful the research.
The Kap København Formation existed aboriginal successful the Pleistocene Epoch, which began 2.58 cardinal years agone and ended 11,700 years ago. At the commencement of the Pleistocene, imperishable crystal covered the northbound rod for the archetypal clip successful millions of years, and it has remained frozen ever since. Furthermore, the Arctic was acold adjacent earlier the Pleistocene, truthful determination mightiness beryllium immoderate permafrost that is adjacent older – with DNA preserved successful it.
However, Antarctica froze implicit overmuch earlier, opening astir 35 cardinal years ago, says Parducci. “So perchance determination you tin spell overmuch deeper successful time.” However, “the diverseness of the plants and animals would beryllium acold less”, says Kurt Kjaer astatine the University of Copenhagen, 1 of the survey authors, due to the fact that Antarctica has been polar godforsaken for truthful long.
Journal reference: Nature, DOI: 10.1038/s41586-022-05453-y
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