NEW YORK – Using ancient genetic sequences, investigators from the Max Planck Institute for the Science of Human History, University of Tubingen, and elsewhere have spelled out some of the social hierarchies at play in a region in southern Germany during the Early and Middle Bronze Age.
"The Lech Valley shows how early social inequality within individual households can be found," first and co-corresponding author Alissa Mittnik, an archaeogenetics, archaeological sciences, and genetics researcher affiliated with Max Planck, University of Tubingen, and Harvard Medical School, said in a statement. She and her colleagues published their findings online today in Science.
Using genome-wide sequence data for more than 100 ancient individuals from the Late Neolithic, Early Bronze, and Middle Bronze Ages found at cemeteries near farm sites in Germany's Lech River valley, the researchers analyzed relationship and ancestry patterns for individuals found at high- or low-status burial sites over time.
Together with isotope and archeological clues, the genetic profiles suggested that individuals from high-status families held onto their influential positions for hundreds of years, though women from outside the community sometimes attained high status there as well. In contrast, the team noted, individuals found in unadorned, lower status graves were typically unrelated.
"Unfortunately, we cannot say whether these individuals were servants and maids or perhaps even enslaved," Mittnik said. "What is certain is that through the male lines, the farmsteads were passed from generation to generation and this system was stable over at least 700 years, across the transition from the Stone Age to the Bronze Age."
The team noted that most studies of ancient genetic and archeological data from Central Europe have focused on relatively large-scale human migrations and population replacements, providing a look at patterns across large swaths of the continent rather than social hierarchies or other more fine-grain relationships between individuals.
"These studies, mostly conducted on a continental scale, cannot fully uncover the complex role of individuals within these processes," the authors wrote.
In an effort to look at historical relationships on a smaller scale, the researchers enriched for and sequenced roughly 1.2 million SNPs in samples from 118 ancient individuals from farm-related cemeteries that go back to the Late Neolithic to Middle Bronze Ages. Using sequences for the 104 individuals who remained after quality control steps, they retraced relationships between individuals within the context of their location and archeologically informed social status over time.
The team focused in further on a group of more than four dozen unrelated individuals for a subsequent population analysis, comparing sequences from representatives from the Corded Ware, Bell Beaker, Early Bronze Age, and Middle Bronze Age with hundreds of modern human genomes as well as genotypes reported for almost 1,000 ancient individuals and more than 1,100 present-day individuals profiled for past studies.
With these data, the researchers were able to retrace ancestry shifts and admixture for the individuals and communities considered — particularly involving the proportions of Western hunter-gatherer, Anatolian Neolithic farmer, and Yamnaya Steppe pastoralist ancestry.
The available genetic data and isotope ratio analyses suggested women in the Lech valley community often moved into the region from elsewhere during or after adolescence, the researchers explained, consistent with the "exogamous marriage" networks proposed from prior isotope analyses in the area.
Likewise, the relationships between individuals at fancy and more modest burial sites revealed that male relatives were often buried at high status graves marked by weapons, headdresses, and other burial goods associated with status, consistent with inherited wealth and status, the team reported. Those results seem to line up with the preponderance of "princely graves" that appeared in the Early Bronze Age, pointing to a rise in social hierarchies.
Some foreign women appeared to benefit from this status-focused system and were buried in high status graves even though they did not appear to be related to the families there, while other unrelated individuals were found at unadorned graves containing goods that linked them to higher status households.
"Considering both grave furnishing and kinship," the authors reported, "people of different status and biological relatedness likely lived together in the same household, which should therefore be seen as complex and socially stratified institutions."