In a major scientific breakthrough, researchers have sequenced ancient DNA from mammoths preserved in Siberian permafrost that lived more than one million years ago, making it by far the oldest genomic data ever recovered from any specimen.
DNA extracted from the teeth of two mammoth specimens is hundreds of thousands of years more ancient than the previous record-holder for oldest sequenced DNA, belonging to a horse that lived between 560,000 and 780,000 years ago, according to a study published on Wednesday in Nature.
The oldest mammoth, known as Krestovka, was dated to about 1.65 million years ago, while a second, Adycha, harkens back about 1.34 million years. The new research also sequenced DNA from a third mammoth, Chukochya, which lived about 870,000 years ago.
“The retrieval of DNA that is more than one million years old confirms previous theoretical predictions that the ancient genetic record can be extended beyond what has been previously shown,” said a team led by Tom van der Valk, a postdoctoral researcher at the Centre for Palaeogenetics in Stockholm, Sweden, in the study.
“We anticipate that the additional recovery and analysis of Early and Middle Pleistocene genomes will further improve our understanding of the complex nature of evolutionary change and speciation,” the researchers added.
While scientists have speculated about the possibility of cloning ancient DNA, stoking wild visions of a Pleistocene Park filled with resurrected animals, it’s important to note that the genetic information from these specimens (and any other long-dead creatures) can not be used to “de-extinct” these bygone species.
“Even the DNA from less than 5,000 year old mammoths is not nearly intact enough for such a process,” said van der Valk in an email. “Actually, you might expect to not find any intact genomes anymore in a dead animal after a few days/weeks, let alone after 5,000 years.”
“The DNA in these, as well as more recently dead mammoths, is broken into many millions of small pieces,” added Love Dalén, the senior author of the new study and a professor of evolutionary genetics at the Centre for Palaeogenetics.
Krestovka and Adycha are so ancient that they precede some of the more familiar extinct species, such as the woolly mammoth and the Columbian mammoth, which had not yet evolved by one million years ago. Krestovka likely belonged to a previously unknown species that had diverged from the steppe mammoth that also lived in Siberia during this era.
The team thinks that the mammoths that traveled from Siberia to North America some 1.5 million years ago belonged to Krestovka’s lineage. Interestingly, the genomic analysis reveals that the Columbian mammoth, which inhabited North America until its extinction some 11,000 years ago, may have been a hybrid of this Krestovka species and the woolly mammoth that emerged some 420,000 years ago.
Adycha and Chukochya, meanwhile, appear to be ancestral forms of the woolly mammoth, which had a wide range across North America and Eurasia until its recent extinction several thousand years ago.
The results of the study chart out, in unprecedented detail, the course of mammoth speciation and mobility across huge swaths of space and time. It also raises the exciting possibility that even older DNA can be extracted from specimens found in permafrost. While the bodies of these animals have been melting out of permafrost for thousands of years, human-driven climate change has accelerated the process, in addition to a thriving new market for mammoth tusks that has motivated excavators in Russia to seek out carcasses.
“Our results highlight the value of perennially frozen environments for extending the temporal limits of DNA recovery, and hint at a future deep-time chapter of ancient DNA research in which specimens from high latitudes will have an important role,” the team concluded.