Population genomics of the Viking world

The maritime expansion of Scandinavian populations during the Viking Age (aboutad 750–1050) was a far-flung transformation in world history1,2. Here we sequencedthe genomes of 442 humans from archaeological sites across Europe and Greenland(to a median depth of about 1×) to understand the global influence of this expansion.We find the Viking period involved gene flow into Scandinavia from the south and east.We observe genetic structure within Scandinavia, with diversity hotspots in the southand restricted gene flow within Scandinavia. We find evidence for a major influx ofDanish ancestry into England; a Swedish influx into the Baltic; and Norwegian influxinto Ireland, Iceland and Greenland. Additionally, we see substantial ancestry fromelsewhere in Europe entering Scandinavia during the Viking Age. Our ancient DNAanalysis also revealed that a Viking expedition included close family members. Bycomparing with modern populations, we find that pigmentation-associated loci haveundergone strong population differentiation during the past millennium, and tracepositively selected loci—including the lactase-persistence allele of LCT and alleles ofANKA that are associated with the immune response—in detail. We conclude that theViking diaspora was characterized by substantial transregional engagement: distinctpopulations influenced the genomic makeup of different regions of Europe, andScandinavia experienced increased contact with the rest of the continent.