Some of the remains have been found since the 1970s, but advanced methods needed to extract and reconstruct DNA from these ancient materials were not yet available.
The oldest of the three mammoths was discovered near the Krestovka River, and they are about 1.2 million years old. The second, from the Adica River, is between 1 million and 1.2 million years old, and the third, from Chukuchia, is about 700,000 years old.
The age of the samples was determined from the geological data about the location and the molecular clock of the DNA. The two methods gave a life of over a million years for the earliest specimens and about 700,000 years for the youngest, one of the oldest known woolly mammoths.
It is the first time that a sequence – the sequence of nucleotides – has been constructed from DNA that is a million years old. To date, the oldest DNA that could be reconstructed was from a horse that lived 700,000 years ago in the Yukon Territory in northern Canada.
“This DNA is incredibly ancient. The samples are a thousand times older than the remains of the Vikings, and they even date from a time when humans and Neanderthals weren’t known yet,” said Luv Dalin, lead author of the study. DNA and Professor of Evolutionary Genetics at CPG.
So it was not easy to extract the DNA from the samples. The researchers determined that only trace amounts of DNA remained in the samples and that the DNA was broken down into small pieces.
“The DNA was broken down into very small pieces, so we had to sequence billions of ultrashort DNA sequences to put the genomes together,” Dalin said.
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