DNA from 11 individuals who lived in Chagyrskaya cave around 51,000 years ago suggests women moved between groups and also shows a high level of inbreeding
19 October 2022
Ancient DNA from a group of Neanderthals who lived together has given us an unprecedented glimpse of the social structure of these extinct human relatives. Among other things, it suggests that their women moved between groups while the men stayed put.
Researchers have previously tried to work out what the social structure of Neanderthal groups was like from evidence such as the layout of caves and footprints, says team member Benjamin Peter at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, but the DNA provides direct evidence. “It’s the first time we’ve been able to do something like this using genetics,” says Peter.
He and his colleagues managed to extract DNA from 15 out of 17 pieces of bone or teeth recovered from the Chagyrskaya cave in the Altai mountains in Siberia, Russia. The DNA showed that some pieces came from the same individuals, so the findings represent 11 individuals in total, including several teenagers and children.
Dating of sediments and bison bones at the site suggests the Neanderthals lived in the cave between 51,000 and 59,000 years ago, while the DNA shows that many of the individuals were related. “We can say that they very likely lived at the same time,” says Peter.
For instance, there is a father and daughter among the remains. The father also shares mitochondrial DNA with two other men, meaning they had a common female ancestor, such as the same grandmother.
Another man and woman are second-degree relatives, meaning the woman might be, say, the grandmother or aunt of the man. The team doesn’t have enough of their DNA to determine the precise relationship.
Peter thinks it is possible that these individuals all died around the same time, but the team doesn’t know how. There are no signs of burial, he says.
The DNA also reveals a very high level of inbreeding, much higher than in modern hunter-gatherer groups, suggesting that the Neanderthal population in the area was very small. “It’s very unusual,” says Peter. “The only thing we’ve found that is comparable are species that are critically endangered, like gorillas.”
However, the team can’t say whether this high level of inbreeding affected the health of these individuals. It may be a result of being an isolated group on the edge of the range of Neanderthals, rather than being true of Neanderthals generally.
“Other Neanderthal sites like Vindija [in Croatia] indicate larger and more diverse populations,” says Chris Stringer at the Natural History Museum in the UK, who wasn’t part of the team.
The researchers also compared the diversity of Y chromosomes, inherited from the father, with that of mitochondrial DNA, inherited from the mother. They found an order of magnitude more mitochondrial diversity, says Peter. “I don’t know any human population where we would see that,” he says.
This suggests that men stayed in the same group where they were born, but that most women moved to different groups.
Female-based migration is the predominant pattern in modern hunter-gatherers, says Stringer, and there is some evidence for it among Neanderthals from the El Sidrón site in northern Spain. “So finding this at another site, with more data, does suggest that this was a common pattern in Neanderthals,” says Stringer.
Peter and his colleagues also tried extracting DNA from 10 specimens from the nearby Okladnikov cave, but only got DNA from two individuals. These weren’t related to each other or to the Chagyrskaya group.
The research team included Svante Pääbo, who won the 2022 Nobel prize in physiology or medicine for his discoveries concerning human evolution and the genomes of our extinct human relatives.
Journal reference: Nature, DOI: 10.1038/s41586-022-05283-y
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