Teeth from mammals buried in the climate of Siberia for more than a million years have extracted the oldest DNA, according to a study published Wednesday, shining a genetic light in the past.
Researchers said the three samples, one around 800,000 years old and two more than a million years old, provide important insights into large Ice Age mammals, including the ancient tradition of the wool raspberry.
The genomes are far superior to the oldest DNA previously classified – a horse dating between 780,000 and 560,000 years ago.
“This DNA is very old. The specimens are a thousand times older than the rest of the Vikings, and even suggest the existence of humans and Neanderthals, ”said Love Dalen, professor of evolutionary genetics at the Center for Palaeogenetics. the Stockholm and senior author of the study published in the journal, Nature.
The mammals were first discovered in the 1970s in Siberia and kept at the Russian Academy of Sciences in Moscow.
Researchers first dated the samples geologically, in comparison to other species, such as small rats, which were known to be unique at certain times and found in the same sediment layers.
This suggested that two of the more than a million year old mammals were old steppe mammals.
The youngest of the trio is one of the earliest woolly mammals found yet.
DNA Jigsaw
Researchers would also extract genetic data from small powdered samples from each raspberry tooth, “much like a pinch of salt you would put on your dinner plate,” Dalen told a news release.
The woolly raspberry tusks emerge from the permafrost on the middle of Wrangel Island in northeastern Siberia. Examination of teeth from the animals has found the oldest DNA ever [Love Dalén via AFP]
Although it had decayed into very small fragments, scientists were able to order tens of millions of chemical pairs, which make up DNA strands and make age estimates from genetic information.
This suggested that the oldest mum, named Krestovka, is even older at about 1.65 million years old, and the second, Adycha, about 1.34 million years old and the Chukochya youngest 870,000 years old.
Dalen said the difference for the oldest raspberry could be a real breakthrough in the DNA extraction process, making the creature appear to be around 1.2 million years old. age, as suggested by the geological evidence.
But he said it was possible that the sample was indeed older and had melted out of the permafrost at one point and then gone out in a younger layer of sediment.
The DNA fragments were like a puzzle with millions of tiny bits, “a way, a way, a way smaller than you would get from high-quality modern DNA”, said lead author Tom van der Valk, of Science for Life, Uppsala University.
Using a genome from an African elephant, modern relatives of the mammal, as a plan for their algorithm, researchers were able to reconstruct parts of the mammoth genomes.
The study found that the oldest Krestovka raspberry represents a previously unknown genetic line, which researchers estimated to have fallen from other mammals about two million years ago and was an ancestor for those who settled North America.
The study also found the line from the million-year-old Adycha steppe mammal to Chukochya and other woolly mammals recently.
He found gene changes associated with life in the Arctic, such as hair loss, thermoregulation, fat deposits and cold tolerance in the oldest sample, indicating that mammals already had hair long before the woolly mammal appeared.
Ice Age Giants
Siberia has altered between the dry and cold conditions of the Ice Age and the warm, wet periods.
Now climate change is melting the permafrost and revealing more samples, Dalen said, although more rain could mean leftovers are washed away.
He said new technologies mean it may be possible to sort even older DNA from what is left in the permafrost, which dates back 2.6 million years.
Researchers want to look at creatures such as the ancestors of moose, muskox, wolves and lemmings, to shed light on the evolution of modern species.
“Genomics has been pushed into a deep era by Ice Age giants,” said Alfred Roca, a professor in the Department of Animal Sciences at the University of Illinois, in an opinion piece published in Nature.
“Maybe the little mammals around them will have a day.”