SummaryThe rich linguistic, ethnic and cultural diversity of Ethiopia provides an unprecedented opportunity to understand the level to which cultural factors correlate with -- and shape -- genetic structure in human populations. Using primarily novel genetic variation data covering 1,268 Ethiopians representing 68 different ethnic groups, together with information on individuals’ birthplaces, linguistic/religious practices and 31 cultural practices, we disentangle the effects of geographic distance, elevation, and social factors upon shaping the genetic structure of Ethiopians today. We provide examples of how social behaviours have directly -- and strongly -- increased genetic differences among present-day peoples. We also show the fluidity of intermixing across linguistic and religious groups. We identify correlations between cultural and genetic patterns that likely indicate a degree of social selection involving recent intermixing among individuals that have certain practices in common. In addition to providing insights into the genetic structure and history of Ethiopia, including how they correlate with current linguistic classifications, these results identify the most important cultural and geographic proxies for genetic differentiation and provide a resource for designing sampling protocols for future genetic studies involving Ethiopians.

The origins of viral pathogens and the age of their association with humans remains largely elusive. To date, there is no direct evidence about the diversity of viral infections in early modern humans pre-dating the Holocene. We recovered two near-complete genomes (5.2X and 0.7X) of human adenovirus C (HAdV-C), as well as low-coverage genomes from four distinct species of human herpesvirus obtained from two 31,630-year-old milk teeth excavated at Yana, in northeastern Siberia. Phylogenetic analysis of the two HAdV-C genomes suggests an evolutionary origin around 700,000 years ago consistent with a common evolutionary history with hominin hosts. Our findings push back the earliest direct molecular evidence for human viral infections by ~25,000 years, and demonstrate that viral species causing common childhood viral infections today have been in circulation in humans at least since the Pleistocene.