Using genome-wide scans and individuals with all four grandparents born in the same settlement, we here demonstrate remarkable geographical structure across 8–30 km in three different parts of rural Europe. After excluding close kin and inbreeding, village of origin could still be predicted correctly on the basis of genetic data for 89–100% of individuals. [. . .]
Such fine-scale differentiation is consistent with the highly nonrandom nature of human mate choice over the millennia. The average distance between the birthplaces of spouses in rural parts of Finland, the Po valley in northern Italy and the isles of Scotland in the nineteenth century was B1.5–3 km.10 Such close endogamy was probably the norm in rural Europe due to lack of transport or economic opportunities. The breakdown of these isolates has since dramatically altered the population structure.11
The exquisite structure preserved in the genomes of people with all grandparents from the same settlement demonstrates that very detailed genetic and geographical ancestry information can be obtained by genome-wide SNP analyses. This provides novel opportunities, under certain circumstances, to predict the micro-geographical origin of an individual. Genetic association studies that include rural populations must also model this genetic structure, but it is not a barrier to gene discovery.12 When whole-genome sequences become widely available, the ability to use many more variants, including rarer ones, to identify short shared genomic segments will perhaps allow routine identification of regional ancestries, given a suitably large and carefully collected reference sample.
Very fine-scale population structure in Europe
Genes predict village of origin in rural Europe: