Population genomics of the Viking world
Authors: Margaryan Ashot , Lawson Daniel , Sikora Martin , Racimo Fernando , Rasmussen Simon , Moltke Ida , Cassidy Lara , Jørsboe Emil , Ingason Andrés , Pedersen Mikkel , Korneliussen Thorfinn , Wilhelmson Helene , Buś Magdalena , de Barros Damgaard Peter , Martiniano Rui , Renaud Gabriel , Bhérer Claude , Moreno-Mayar J. Víctor , Fotakis Anna , Allen Marie , Molak Martyna , Cappellini Enrico , Scorrano Gabriele , Buzhilova Alexandra , Fox Allison , Albrechtsen Anders , Schütz Berit , Skar Birgitte , Arcini Caroline , Falys Ceri , Jonson Charlotte Hedenstierna , Błaszczyk Dariusz , Pezhemsky Denis , Turner-Walker Gordon , Gestsdóttir Hildur , Lundstrøm Inge , Gustin Ingrid , Mainland Ingrid , Potekhina Inna , Muntoni Italo , Cheng Jade , Stenderup Jesper , Ma Jilong , Gibson Julie , Peets Jüri , Gustafsson Jörgen , Iversen Katrine , Simpson Linzi , Strand Lisa , Loe Louise , Sikora Maeve , Florek Marek , Vretemark Maria , Redknap Mark , Bajka Monika , Pushkina Tamara , Søvsø Morten , Grigoreva Natalia , Christensen Tom , Kastholm Ole , Uldum Otto , Favia Pasquale , Holck Per , Allmäe Raili , Sten Sabine , Arge Símun , Ellingvåg Sturla , Moiseyev Vayacheslav , Bogdanowicz Wiesław , Magnusson Yvonne , Orlando Ludovic , Bradley Daniel , Jørkov Marie Louise , Arneborg Jette , Lynnerup Niels , Price Neil , Gilbert M. Thomas , Allentoft Morten , Bill Jan , Sindbæk Søren , Hedeager Lotte , Kristiansen Kristian , Nielsen Rasmus , Werge Thomas , Willerslev Eske 
Published: July 2019

The Viking maritime expansion from Scandinavia (Denmark, Norway, and Sweden) marks one of the swiftest and most far-flung cultural transformations in global history. During this time (c. 750 to 1050 CE), the Vikings reached most of western Eurasia, Greenland, and North America, and left a cultural legacy that persists till today. To understand the genetic structure and influence of the Viking expansion, we sequenced the genomes of 442 ancient humans from across Europe and Greenland ranging from the Bronze Age (c. 2400 BC) to the early Modern period (c. 1600 CE), with particular emphasis on the Viking Age. We find that the period preceding the Viking Age was accompanied by foreign gene flow into Scandinavia from the south and east: spreading from Denmark and eastern Sweden to the rest of Scandinavia. Despite the close linguistic similarities of modern Scandinavian languages, we observe genetic structure within Scandinavia, suggesting that regional population differences were already present 1,000 years ago. We find evidence for a majority of Danish Viking presence in England, Swedish Viking presence in the Baltic, and Norwegian Viking presence in Ireland, Iceland, and Greenland. Additionally, we see substantial foreign European ancestry entering Scandinavia during the Viking Age. We also find that several of the members of the only archaeologically well-attested Viking expedition were close family members. By comparing Viking Scandinavian genomes with present-day Scandinavian genomes, we find that pigmentation-associated loci have undergone strong population differentiation during the last millennia. Finally, we are able to trace the allele frequency dynamics of positively selected loci with unprecedented detail, including the lactase persistence allele and various alleles associated with the immune response. We conclude that the Viking diaspora was characterized by substantial foreign engagement: distinct Viking populations influenced the genomic makeup of different regions of Europe, while Scandinavia also experienced increased contact with the rest of the continent.