Neanderthal families lived in small groups, but not in completely isolated communities since women mainly migrated from other groups. This is what an international study has concluded, published in the journal Nature, that has analyzed the genomic sequence of 17 Neanderthal remains, belonging to 13 different individuals. This work represents the largest number of Neanderthal samples sequenced in a single study.
In the remains analyzed and discovered in two Siberian caves, multiple relatives have been found, including a father and his teenage daughter. The investigation concludes that the communities that inhabited both caves seem to have been a small group of close relatives that lived together during the same period of time.
“For the first time we have been able to sequence the genome of multiple individuals from a Neanderthal community in Siberia. It is the clearest picture to date of how a Neanderthal community was organized”, Laurits Skov, first author of the study and researcher at the Max Planck Institute for Evolutionary Anthropology, explains to SINC.
Very human Neanderthals
Although in recent years genomic studies have provided important information on the history of the Neanderthals, until now not much was known about the organization of their communities.
The first work on the Neanderthal genome sequence was published in 2010, also led by researchers from the Max Planck Institute for Evolutionary Anthropology. Now, this work by Skov and his team represents a great scientific approach to the social organization of the homo neanderthalensis.
“Our study provides a concrete idea of what a Neanderthal community might have looked like. It makes Neanderthals look much more human,” says Benjamin Peter, co-author of the research.
The work focused on southern Siberia, an area previously very fruitful for DNA research, including the discovery of the Denisovans in the famous Denisova cave.
The researchers analyzed Neanderthal remains from the Chagyrskaya and Okladnikov caves – some 100 kilometers from the Denisova cave – inhabited by Neanderthals some 54,000 years ago. The DNA of 17 Neanderthal remains was successfully identified, 7 men and 6 women, of which 8 were adults and 5 were children and young people. In their mitochondrial DNA, the researchers found so-called heteroplasmies shared between individuals. Heteroplasmias are a special type of genetic variant that is only maintained for a small number of generations.
With this method, the remains of a Neanderthal father and his teenage daughter were identified. A couple of second-degree relatives were also found, a child and an adult woman, who could perhaps be a cousin, aunt or grandmother. The combination of heteroplasmies and related individuals suggests that the Neanderthals in Chagyrskaya cave developed their lives at the same time point.
low genetic diversity
Another surprising finding is that genetic diversity is extremely low within this Neanderthal community, which would be made up of a small group of 10 to 20 individuals. This is much lower than those recorded for any ancient or current human community, and is more similar to the size of groups of species on the brink of extinction.
However, Neanderthals were not isolated. By comparing the genetic diversity on the Y chromosome, which is inherited from father to son, with the diversity of mitochondrial DNA, which is inherited from mothers, the researchers found that mitochondrial genetic diversity was much greater than the diversity on the Y chromosome. which indicates that these Neanderthal communities were mainly linked by female migration.
“Women moved more between Neanderthal groups than men. The communities in Chagyrskaya were a small group in which a large part of its members were women who came from other communities”, Skov explains to SINC.
Despite the proximity to Denisova Cave, these migrations do not appear to have involved Denisovans: the researchers found no evidence of Denisovan gene flow in the Chagyrskaya Neanderthals.
Other Neanderthal communities
For Skov, it is important to highlight that “we do not know if the conclusions about the Neanderthals that inhabited the Chagyrskaya cave can be applied to other Neanderthal communities, such as those that may have inhabited present-day Spain.”
Precisely, this will be the focus of the next works. “We will study if this type of social organization was common in all Neanderthals, to understand how connected the different communities were to each other and to look for evidence of whether women’s migration also took place in them,” he says.
Teaming up with a recent Nobel
Among the signatories of the study is the Swedish researcher Svante PääboNobel Prize in Medicine 2022, one of the founders of the Max Planck Institute for Evolutionary Anthropology from Leipzig. His discoveries of the Neanderthal and Denisovan genomes, as well as the evolution of humans themselves, earned him a worthy Swedish award this October.
Laurits Skov highlights that thanks to the previous work of Pääbo this study has been possible. “I feel very fortunate to have been able to work with him, he has been a great guide”, the researcher admits to SINC.
Researchers from Australia, Austria, Canada, France, Germany, Israel, Italy, Poland, Russia and the United Kingdom have participated in the study.