Since the first Neanderthal draft genome was published in 2010, scientists from the Max Planck Institute for Evolutionary Anthropology have sequenced a further 18 genomes from 14 archaeological sites throughout Eurasia. Now, the experts turned their attention to southern Siberia – a regions where Denisovan hominin remains were also discovered for the first time – to find out more about the social structure of Neanderthals.
By focusing on the Neanderthal remains in Chagyrskaya and Okladnikov Caves, the researchers managed to successfully retrieve DNA samples from 17 fossils, including bones and tooth fragments. The analyses revealed that Neanderthals briefly occupied these sites about 54,000 years ago, and were hunting ibex, horses, bison, and other animals which were migrating through the nearby rivel valleys. However, they collected raw materials for their stone tools dozens of kilometers away.
Although previous data suggest that Neanderthals inhabited the Altai mountains even earlier – around 120,000 years ago – genetic analyses showed that the Neanderthals from the Chagyrskaya and Okladnikov Caves were not descendants of these earlier groups, but were closer related to European Neanderthals.
Among the remains found in these caves were those of a Neanderthal father and his teenage daughter, as well as a pair of second-degree relatives – a young boy and an adult female (possibly a cousin, aunt, or grandmother). Genetic investigations revealed that these Neanderthals must have lived – and died – at around the same time.
“The fact that they were living at the same time is very exciting. This means that they likely came from the same social community. So, for the first time, we can use genetics to study the social organization of a Neanderthal community,” said lead author Laurits Skov, a postdoctoral fellow at the Max Planck Institute.
Moreover, according to the scientists, this Neanderthal community was characterized by an extremely low genetic diversity, consistent with a group size of ten to 20 individuals. However, Neanderthals did not seem to live in completely isolated communities. By comparing the genetic diversity on the Y-chromosome (inherited from father to son) with the mitochondrial DNA diversity (inherited from mothers), the researchers found that the mitochondrial genetic diversity was considerably higher than the Y-chromosome diversity, suggesting that these Neanderthal communities were mainly linked by female migration. Despite the proximity to Denisova Cave, these migrations do not seem to have involved Denisovans, since the scientists found no proof of Denisovan gene flow in the Chagyrskaya Neanderthals during the last 20,000 years before these individuals lived.
“Our study provides a concrete picture of what a Neanderthal community may have looked like,” said senior author Benjamin Peter, an expert in Evolutionary Genetics at the Max Planck Institute. “It makes Neanderthals seem much more human to me.”
The study is published in the journal Nature.
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