Network of large pedigrees reveals social practices of Avar communities

From 567/68 CE, the onset of the Avar period, populations from the Eurasian Steppe settled in the Carpathian Basin for approximately 250 years. An extensive sampling for archaeogenomics (424 individuals) and isotopes, combined with archaeological, anthropological, and historical contextualization on four Avar-period cemeteries, allowed for a detailed description of the genomic structure of these communities and their kinship and social practices. We present the largest set of pedigrees reconstructed so far through aDNA, spanning over 9 generations comprising ~300 individuals. We uncover a strict patrilineal kinship system, where patrilocality and female exogamy were the norm and multiple reproductive partnering and levirate unions were commonly practiced. The absence of consanguinity indicates this society maintained a detailed memory of ancestry over generations. These kinship practices correspond to the evidence of historical sources and anthropological research on Eurasian Steppe societies. Novel network analyses of identity-by-descent DNA connections suggest social cohesion between communities was maintained via females. Finally, despite the absence of major ancestry shifts, the level of resolution reached by our analyses allowed us to detect genetic discontinuity: the replacement of a community at one of the studied sites. This was paralleled with changes in the archaeological record and was likely due to local political realignment.