A group of scientists has found a tooth of a child at least 130,000 years old in Laos, belonging to Denisovan men, related to Neanderthals, which shows that this species lived in Southeast Asia, according to a study published on Tuesday. (17).
The Denisovan man was identified in 2010 in a Siberian cave. Thanks to DNA analysis of a small finger bone, paleontologists were able to sequence the entire genome.
In 2019, scientists also found a jaw with large teeth in the Tibetan plateau, demonstrating that the species also lived in this region of China.
But apart from these fossils, the scientific community had no other elements to study Denisovans than genes. Before disappearing, the species interbred with Homo sapiens and left traces of its DNA in the current populations of Southeast Asia and Oceania.
Geneticists deduced that “the modern ancestors of these populations intermingled with the Denisovans in Southeast Asia,” paleontologist Clément Zanolli, co-author of the study published Tuesday in Nature Communications, told AFP.
But “physical proof” of its presence in this part of the Asian continent was lacking, added the scientist from CNRS, the French national center for scientific research.
Until a team of scientists decided to excavate the Cobra cave in northeastern Laos.
The cave, situated on a mountain, was discovered in 2018 by cavers near the Tam Pa Ling deposit, where human remains had already been discovered. The sediments preserved in the walls contained fragments of animal bones, as well as a molar tooth.
The tooth had a “typically human” morphology, says Clément Zanolli. The study highlights that it likely belonged to a child between 3 and 8 years old.
As it was very old, it was impossible to radiocarbon date it. In addition, its DNA was poorly preserved due to the hot and humid climate, points out paleoanthropologist Fabrice Demeter, co-author of the study.
– Date the sediments –
The researchers decided to overcome this obstacle by dating the sediments that contained the dental remains and then its upper layer. They reached a range between 160,000 and 130,000 years old.
Then they studied the inside of the tooth, temporarily taken to Denmark.
“The proteins allowed us to identify the sex, female, and confirm that it belonged to the genus Homo,” explains Fabrice Demeter, a researcher at the University of Copenhagen and affiliated with the National Museum of Natural History in Paris.
Surprisingly, the structure of the tooth turned out to be close to that of the molars of the Denisovan man of Tibet. And it could easily be distinguished from other species.
The only problem was that it had characteristics common to Neanderthals, genetically close to Denisovans.
“But we leaned towards Denisova because we never found evidence that Neanderthals moved that far east,” explains Zanolli.
The study concludes that Denisovans occupied this region of Asia and adapted to a wide range of environments, from cool altitudes to tropical climates.
A “versatility” that their cousins, Neanderthals, did not seem to have, as they were more present in the cold regions of the West, explains Fabrice Demeter.
It was in the tropics that the last Denisovans were able to meet and interbreed with Pleistocene human groups, who passed on their genetic heritage to present-day Southeast Asian populations.