Anthropologists have pieced together the most complete Stone Age family tree so far, spanning seven generations of relatives. Genetic studies of the remains of dozens of people in one burial site in France reveal some surprising insights into the family and social dynamics of the time.
The burial site, known as Gurgy Les Noisats, has been dated to between about 6,300 and 6,700 years ago during the Neolithic period, when humans began to settle into localized agricultural communities. Within a series of graves the remains of 128 individuals have been identified, and the lack of any monuments or treasures suggest they were “commoners” of the time.
For the new study, researchers at PACEA and the Max Planck Institute for Evolutionary Anthropology analyzed the genomes of 94 individuals buried at Gurgy, to build family trees of their relationships. The team investigated a range of factors, such as age at death, genetic sex, strontium isotope ratios (which indicate areas of origin and migration patterns), and mitochondrial and Y chromosome DNA data, which indicate their mother’s and father’s lineages, respectively. From this, the scientists were able to connect 12 individuals over five generations in one family tree, and in another an astonishing 64 people over seven generations.
“Since the beginning of the excavation, we found evidence of a complete control of the funerary space and only very few overlapping burials, which felt like the site was managed by a group of closely related individuals, or at least by people who knew who was buried where,” said Stéphane Rottier, corresponding author of the study.
The data revealed a number of fascinating insights into this Stone Age society. Generations were almost always linked to the previous generation through the father’s lineage, while there weren’t many adult women buried there who shared that paternal line. Instead, the adult women who were present had strontium isotope ratios that indicated they had migrated from elsewhere. Together, this information suggests the group practiced patrilocality, a social structure where men usually live in the same communities for their whole lives while women move into their partner’s community.
Interestingly, the women who joined the community as adults were only distantly related and had different strontium isotope ratios, indicating that multiple groups in neighboring regions were meeting and exchanging members.
Siblings buried at Gurgy were also found to always share both of their parents. No half-siblings were detected, suggesting that the society was monogamous. Alternatively, the team acknowledges the possibility that perhaps half-siblings were deliberately excluded from the family cemetery.
The genetic data also seems to suggest the origin and ending of the site’s use by the family. The largest family tree can be traced back to one man whose remains were found in a secondary deposit in the grave of a woman, indicating his bones had been brought over from another site. That suggests he was of “great significance” to the family, according to the scientists.
Even more intriguingly, there were no children or teens buried at the site within the first few generations, while the last few generations saw no adult burials. That suggests the family only actively used the burial site for three to four generations – or about a century – before moving on to a new location.
All up, the study provides some fascinating social insights into this Stone Age family, including that they were relatively successful during their time in Gurgy.
“We observe a large number of full siblings who have reached reproductive age,” said Maïté Rivollat, first author of the study. “Combined with the expected equal number of females and significant number of deceased infants, this indicates large family sizes, a high fertility rate and generally stable conditions of health and nutrition, which is quite striking for such ancient times.”
The research was published in the journal Nature.
Source: Max Planck Institute