How did the Neanderthals live together? How big were their groups and what role did family relationships play? Answers to these questions are now provided by a genome analysis of 13 Neanderthals, several of whom apparently lived in the same social community at the same time. The results indicate that some of the individuals were related to each other. Furthermore, the genetic data suggest that it was primarily migratory women who provided the links between different Neanderthal groups.
Neanderthals lived in Eurasia for around 100,000 years. From archaeological finds we know that they made tools, hunted animals and made jewelry with ritual symbols, just like modern humans. Genome analyzes have revealed that they even reproduced with modern humans and that there is also a small proportion of Neanderthal DNA in our current genome. However, many aspects of the social structure of the Neanderthals were previously unclear. An important reason for this is that previous genome analyzes usually came from individual individuals from different sites, so that the genetic data hardly allowed any conclusions to be drawn about the social group.
Genomes of several group members
A research team led by Laurits Skov from the Max Planck Institute for Evolutionary Anthropology in Leipzig has now analyzed the genomes of several members of a group of Neanderthals for the first time. “We have succeeded in removing and sequencing genetic material from 17 different Neanderthal remains – more than ever before in a single study,” reports the team of authors, which also includes this year’s Nobel Prize winner for medicine, Svante Pääbo. The Neanderthal fossils came from two caves in Siberia, the Chagyrskaya and Okladnikov Caves, and have been dated to be around 54,000 years old.
The genetic analyzes revealed that the 17 fossils came from 13 different individuals, 11 of them from the Chagyrskaya Cave. Seven individuals were male and six were female. Using anatomical features of the preserved bones and teeth, the research team determined that they were eight adults and five children and adolescents. The genome analyzes also revealed a unique feature: “Some of the Chagyrskaya individuals were closely related, which indicates that at least some of the individuals lived at the same time,” say the researchers.
Family members identified
The closest related couple that Skov and his colleagues discovered were a father and his teenage daughter. Another male individual was probably related to the father through a female line – the two men may have shared a grandmother. Also among the remains were two individuals who were second-degree relatives: a boy of about eight to 12 years of age and an adult woman who may have been his cousin, aunt or grandmother.
“The fact that they lived at the same time is very exciting to us because it means they may have belonged to the same social community. This is the first time we can use genetics to study the social organization of a Neanderthal group,” says Skov. The genome data offered further insights beyond the direct family relationships: From the low genetic diversity, the authors concluded that the social groups within which the Neanderthals predominantly reproduced were very small and probably only consisted of ten to 20 individuals.
Genetic variation thanks to female migration
To find out more about gender roles, Skov and his colleagues also compared the genetic diversity on the Y chromosome, passed from father to son, and the diversity in mitochondrial DNA, passed from mother to child. The result: “The mitochondrial genetic diversity was much greater than the diversity on the Y chromosome,” according to the researchers. So it was probably common for Neanderthal females to leave their own group and join their male partner’s group. “So Neanderthal communities were genetically linked primarily through the migration of women,” the authors said.
To what extent these results can be extrapolated to other populations of Neanderthals is not yet clear. From the authors’ point of view, it would also be possible that the low genetic diversity and the connection through migrating women are mainly related to the isolated geographical location on the edge of the Siberian Altai Mountains. “Future studies should therefore aim, if possible, to examine multiple individuals from other Neanderthal communities in other parts of Eurasia in order to gain further insights into the social organization of our closest evolutionary relatives,” the authors write.
Source: Laurits Skov (Max Planck Institute for Evolutionary Anthropology, Leipzig) et al., Nature, doi: 10.1038/s41586-022-05283-y