Different Levels of Genomic Diversity and Admixture for Stone-Age Scandinavian Foragers and Farmers

Prehistoric population structure associated with the transition to an agricultural lifestyle in Europe remains contentious. We analyzed population-genomic data from eleven Scandinavian Stone-age human remains, including seven individuals from hunter-gatherer contexts, and four individuals from farmer contexts in Scandinavia. Despite their close geographical proximity, the genetic differentiation between the two Stone-Age groups is greater than that of contemporary European populations, with the hunter-gathers having about half the genetic diversity of the Neolithic farmers. Additionally, the Scandinavian Neolithic farmers have much greater degree of hunter-gatherer-related admixture than the Tyrolean Iceman who is also from a farming context. This contrasts with the Scandinavian hunter-gatherers who display little introgression from farmers. Our findings suggest that Stone-Age foraging groups were historically in low numbers due to oscillating living conditions or restricted carrying-capacity and that they were partially incorporated into expanding farming groups.