The specimen belonged to a previously unknown Siberian lineage.
Scientists recently managed to extract a genome from a mammoth molar that is over a million years old. It is by far the oldest DNA sequenced to date.
RECORD GENETIC SEQUENCING
The previous record was set in 2013 by a team of Danish researchers, who succeeded in sequencing DNA from a 780,000-year-old horse bone. Finding such ancient genomes is a real challenge because DNA strands tend to get smaller and smaller after the death of an organism. Luckily, Siberian permafrost provides the necessary conditions for optimal storage, with a freezing but constant temperature helping slow DNA fragmentation.
As part of work presented in the journal Nature, an international team of scientists succeeded in isolating molars’ DNA from three mammoths, the remains of which had been exhumed from the Siberian permafrost in the 1970s. According to their analyzes, the oldest belonged to a specimen that lived 1.2 to 1.6 million years ago.
However, although permafrost helped prolong the life of the genome, the samples contained very little DNA. Fortunately, researchers led by Love Dalén, an evolutionary geneticist at the Swedish Museum of Natural History (SMNH) in Stockholm, relied on an advanced genomic sequencing method that allowed them to recover a workable number of base pairs from the Nuclear DNA.
Molar of the Krestovka specimen – © CPG
ANALYZES PROVIDING A BETTER OVERVIEW OF THE DEVELOPMENT OF MAMMOTHS
The sequence of the ancient genome has revealed several interesting things. In particular, it turned out that the oldest DNA belonged to a type of mammoth very different from other Siberian species known over a million years ago. This newly identified line has been named “Krestovka” to honor the region where the animal was originally found.
According to the study’s authors, this finding was shocking, given that all of the research conducted to suggest that Siberia at the time was home to a single species of mammoth, known as the mammoth. Given the established timeline, the team also believes that this previously unknown lineage may have formed the North American population about 1.5 million years ago.
Once isolated in North America, this ancestral line diverged further. The researchers found that Columbus mammoths owed half of their genetic makeup to the Krestovka line, while the other half came from woolly mammoths.
