Recent research using ancient genetic data is shedding new light on the social organisation of Neanderthal communities.
While a number of previous genetic studies have investigated wider Neanderthal populations and their connections to modern humans, far less is known about the smaller groups in which some of our closest ancient relatives lived and socialised. In order to better understand the subject, researchers conducted genetic analysis of bone and tooth remains from 13 Neanderthals from two sites in the foothills of the Altai Mountains in southern Siberia: 11 from Chagyrskaya Cave and two from Okladnikov Cave. These Middle Palaeolithic sites are believed to have been used mainly as short-term hunting camps over a period of a few millennia or less, at around the same time c.44,000-59,000 years ago.
The genetic data revealed that the two individuals from Okladnikov Cave were not closely related to each other, nor to any of the individuals from Chagyrskaya Cave. Among the 11 Chagyrskaya Neanderthals, however, the researchers were able to identify several with close familial relationships, including a father and his teenage daughter, as well as a pair of second-degree relatives whose exact relationship it is not possible to determine. The study also identified several heteroplasmies – a type of genetic variant that usually persists for fewer than three generations – shared between individuals at Chagyrskaya Cave, further reinforcing the conclusion that all of these individuals lived around the same time and were likely part of the same social group. This meant that, for the first time, it was possible to use genetics to study the social organisation of a single, known Neanderthal community.
Analysis of the Chagyrskaya community revealed very low levels of genetic diversity, suggesting a group size of around 20 individuals. This is supported by other studies that have pointed to small Neanderthal community-sizes based on fossilised footprints and spatial patterns of site-use, but it is uncertain whether the extremely small size of the Chagyrskaya group is representative of Neanderthal behaviour across Eurasia at this time or if it is particular to more isolated groups in the Altai Mountains.
However, even these communities would not have been completely isolated, and the researchers also wanted to explore the possible connections between different groups. In order to do so, they looked at the difference in genetic diversity in the Neanderthals’ Y-chromosome sequences (which are inherited father-to-son) and in their mitochondrial DNA (which is inherited maternally). They found a much greater degree of diversity in the mitochondrial DNA, indicating that females often moved between Neanderthal communities, while the males generally remained in the group where they were born.
This research, which has now been published in Nature (https://doi.org/10.1038/s41586-022-05283-y), represents one of the largest genetic studies of a Neanderthal population ever carried out, and possibly the first examples of documented individual familial relationships, including a father–daughter pair. The results offer a remarkable insight into the social lives of Neanderthals and the size, sex composition, and organisation of the communities in which they lived.
Images: Dr Bence Viola; illustration by Tom Bjorklund
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