Ancient DNA sheds light on genetic diversity of post-Roman elites

A new study of ancient DNA, conducted by a team of international researchers and co-led by Krishna R. Veeramah, Ph.D., of Stony Brook University, provides insight into the development and social structures of rural European communities after the fall of the Roman Empire.

The results, published in an article in Proceedings of the National Academy of Sciences (PNAS), suggest that the early medieval elites, or those with higher social status, initially consisted of several families with distinct genetic ancestry. However, over time, these families intermarried and local communities also incorporated genetically diverse newcomers from different social and cultural backgrounds.

The research team combined paleogenomic, archaeological, and isotopic data to shed light on the community that used a cemetery in Collegno, Italy, as a burial site from the 6th to the 8th century CE. The researchers sequenced and analyzed the genomes of 28 individuals from the cemetery and integrated data from 24 previously published genomes. They also studied patterns of social mobility, burial patterns, and diet of the individuals.

“When the Roman Empire collapsed, we didn’t really know how new communities formed, and yet many of these communities would become the basis of modern European countries,” says Veeramah, an associate professor in the College of Arts and Sciences’ Department of Ecology and Evolution and director of the Veeramah Lab, which studies evolutionary genomics.

“Our study reveals that these elites were surprisingly genetically diverse and that, in the process of creating new European communities in medieval times, families of diverse genetic ancestry came together to form ruling groups.”

“In 2018, our team published a paper demonstrating genomic and cultural similarities between Collegno and Szólád, a village in modern-day Hungary that showed significant correspondence between individuals of Northern European ancestry in both cases,” adds Patrick Geary, Ph.D., of the Institute for Advanced Study.

“Our new study follows the transformation of this Italian community over a century and shows how new groups settled and merged with existing inhabitants.”

The researchers found that the Collegno community was initially founded and organized around a network of closely related individuals, likely from several elite families. But over time, they evolved into a single, extended lineage spanning at least five generations.

Veeramah and his colleagues believe that individuals from this lineage had a higher rank in society because of their richer diet and the highly detailed and probably more expensive objects with which they were buried, such as elaborate weapons and belts (see attached photos).

The results also show that while the community of Collegno was initially established by these elite families, the majority of whom came from northern Europe, the community later incorporated individuals of other origins and genetic backgrounds, including people from the surrounding area.