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NEWS 17 FEBRUARY 2021
Million-year-old mammoth genomes shatter record for oldest ancient DNA
Permafrost-preserved teeth, up to 1.6 million years old, identify a new kind of mammoth in Siberia.
Permafrost-preserved teeth, up to 1.6 million years old, identify a new kind of mammoth in Siberia.
www.nature.com
An illustration of the steppe mammoths that preceded the woolly mammoth
Ancient DNA retrieved from different mammoth species is illuminating a complex evolutionary picture.Credit: Beth Zaiken/Centre for Palaeogenetics
The million-year-old genome is here. Mammoth teeth preserved in eastern Siberian permafrost have produced the oldest ancient DNA on record, pushing the technology close to — but perhaps not past — its limits.
Genomic DNA extracted from a trio of tooth specimens excavated in the 1970s has identified a new kind of mammoth that gave rise to a later North American species. The findings were published in Nature on 17 February1.
“I love the paper. I’ve been waiting for that paper for, what, eight years now,” says Ludovic Orlando, an ancient-DNA specialist at the Centre for Anthropobiology and Genomics of Toulouse in France, who co-led a 2013 effort that sequenced the previous oldest ancient DNA — a genome from a 560,000-to-780,000-year-old horse leg bone2. “I’m pleased to lose this record, because it was a heavy one,” he says.
Researchers had suspected that ancient DNA could survive beyond one million years, if the right sample could be found. Once an organism dies, its chromosomes shatter into pieces that get shorter over time. Eventually, the DNA strands become so small that — even if they can be extracted — they lose their information content.
Orlando’s team found that fragments as short as 25 DNA letters in their horse bone, from the Canadian Yukon Territory, could still be interpreted. They estimated that million-year-old remains preserved in the constant cold of permafrost — which slows DNA fragmentation — should also contain DNA fragments of that length. “My only doubt: does such a sample exist?” Orlando says.