News – AU – The world’s oldest DNA sequenced from mammoths that are millions of years old

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In this undated photo, a volunteer is working on the excavation site of a mammoth carcass in Siberia near Lake Kara (Alexei Tikhonov / Pitulko et al / Science via AP)

Teeth of mammoths buried in Siberian permafrost for more than a million years have produced the world’s oldest DNA ever sequenced and pointed the genetic searchlight into the deep past, according to a study published Wednesday

Researchers said the three specimens, one around 800000 years old and two over a million years old, provide vital insight into the vast Ice Age mammals, including the ancient legacy of the woolly mammoth

The genomes far surpass the oldest previously sequenced DNA – a horse that was found before 780000 to 560000 years ago

“This DNA is incredibly old. The samples are a thousand times older than the remains of the Vikings and even date before humans and Neanderthals even existed,” said Love Dalen, professor of evolutionary genetics at the Center for Paleogenetics in Stockholm, lead author of the study published in Nature / p>

The mammoths were originally discovered in Siberia in the 1970s and held at the Russian Academy of Sciences in Moscow

Researchers first geologically dated the specimens by comparing them to other species, such as small rodents, which are known to be unique for certain periods of time and to reside in the same sedimentary layers

This suggested that two of the mammals were ancient steppe mammoths that were more than a million years old

They also extracted genetic data from tiny powder samples from each mammoth tooth, “essentially like a pinch of salt you would put on your plate,” Dalen told a news conference

While it had broken into very small fragments, scientists were able to sequence the tens of millions of chemical base pairs that make up the strands of DNA and make age estimates based on genetic information

This suggests that the oldest mammoth, named Krestovka, is even older at around 1.65 million years old, while the second, Adycha, is around 1.34 million years old, and the youngest Chukochya is 870000 years old

Dalen said the discrepancy for the oldest mammoth could be an underestimate in the DNA dating process, meaning the creature was likely around 1.2 million years old, as evidenced by the geological evidence

But he said it was possible that the sample was actually older and thawed out of the permafrost at one point and then wedged itself in a younger layer of sediment

The DNA fragments were like a puzzle with millions of tiny pieces, “much, much, much smaller than you would expect from modern high-quality DNA,” said lead author Tom van der Valk of the Science for Life Laboratory at Uppsala University

Using a genome of an African elephant, a modern relative of the mammoth, as a blueprint for their algorithm, researchers were able to reconstruct parts of the mammoth genome

The study found that the older Krestovka mammoth represented a previously unrecognized genetic lineage that researchers estimated to be different from other mammoths about two million years ago and ancestor of those who colonized North America

The study also traced the lineage from the million-year-old Adycha steppe mammoth to Chukochya and other newer woolly mammoths

Variants of genes associated with Arctic life, such as hairiness, thermoregulation, fat deposits, and cold tolerance, have been found in older specimens, suggesting that mammoths were hairy long before the woolly mammoth appeared

Now climate change is melting the permafrost, revealing more specimens, Dalen said, although higher rainfall could mean debris being washed away

He said that new technologies could make it possible to sequence even older DNA from remnants of permafrost, which is 2 years old, 6 million years old

Researchers would like to look at creatures such as the ancestors of moose, musk ox, wolves, and lemmings to shed light on the evolution of modern species

“The giants of the Ice Age drove genomics down,” said Alfred Roca, a professor in the University of Illinois Department of Animal Sciences, in a comment published in Nature

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Mammoth, DNA, Mammuthus primigenius, steppe mammoth, genetics

News – AU – The oldest DNA in the world that was sequenced from mammoths that were millions of years old

Source: https://www.ctvnews.ca/sci-tech/world-s-oldest-dna-sequenced-from-million-year-old-mammoths-1.5313882