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), Viking sailors reached Greenland, North America, and large parts of western Eurasia, and left a legacy that persists 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 BCE) 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.

87 The Viking maritime expansion from Scandinavia (Denmark, Norway, and Sweden) marks one 88 of the swiftest and most far-flung cultural transformations in global history. During this time 89 (c. 750 to 1050 CE), the Vikings reached most of western Eurasia, Greenland, and North 90 America, and left a cultural legacy that persists till today. To understand the genetic structure 91 and influence of the Viking expansion, we sequenced the genomes of 442 ancient humans from 92 across Europe and Greenland ranging from the Bronze Age (c. 2400 BC) to the early Modern 93 period (c. 1600 CE), with particular emphasis on the Viking Age. We find that the period 94 preceding the Viking Age was accompanied by foreign gene flow into Scandinavia from the 95 south and east: spreading from Denmark and eastern Sweden to the rest of Scandinavia. 96Despite the close linguistic similarities of modern Scandinavian languages, we observe genetic 97 structure within Scandinavia, suggesting that regional population differences were already 98 present 1,000 years ago. We find evidence for a majority of Danish Viking presence in England, 99 Swedish Viking presence in the Baltic, and Norwegian Viking presence in Ireland, Iceland, and 100Greenland. Additionally, we see substantial foreign European ancestry entering Scandinavia 101 during the Viking Age. We also find that several of the members of the only archaeologically 102 well-attested Viking expedition were close family members. By comparing Viking Scandinavian 103 genomes with present-day Scandinavian genomes, we find that pigmentation-associated loci 104 have undergone strong population differentiation during the last millennia. Finally, we are able 105 to trace the allele frequency dynamics of positively selected loci with unprecedented detail, 106 including the lactase persistence allele and various alleles associated with the immune response. 107We conclude that the Viking diaspora was characterized by substantial foreign engagement: 108 distinct Viking populations influenced the genomic makeup of different regions of Europe, 109 while Scandinavia also experienced increased contact with the rest of the continent. 110 111

Human parvovirus B19 (B19V) is a ubiquitous human pathogen associated with a number of conditions, such as fifth disease in children and arthritis and arthralgias in adults. B19V is thought to evolve exceptionally rapidly among DNA viruses, with substitution rates previously estimated to be closer to those typical of RNA viruses. On the basis of genetic sequences up to ∼70 years of age, the most recent common ancestor of all B19V has been dated to the early 1800s, and it has been suggested that genotype 1, the most common B19V genotype, only started circulating in the 1960s. Here we present 10 genomes (63.9-99.7% genome coverage) of B19V from dental and skeletal remains of individuals who lived in Eurasia and Greenland from ∼0.5 to ∼6.9 thousand years ago (kya). In a phylogenetic analysis, five of the ancient B19V sequences fall within or basal to the modern genotype 1, and five fall basal to genotype 2, showing a long-term association of B19V with humans. The most recent common ancestor of all B19V is placed ∼12.6 kya, and we find a substitution rate that is an order of magnitude lower than inferred previously. Further, we are able to date the recombination event between genotypes 1 and 3 that formed genotype 2 to ∼5.0-6.8 kya. This study emphasizes the importance of ancient viral sequences for our understanding of virus evolution and phylogenetics.

Death of a spouse is associated with poorer physical and mental health. We followed all married individuals, born from 1902 to 1942, during the period from 1987 to 2002, and found that widows and widowers had higher risk for hip fracture, compared with still married women and men. Introduction Spousal bereavement can lead to poorer physical and mental health. We aimed to determine whether married women and men had an elevated risk of hip fracture after death of a spouse. Methods In a retrospective cohort study, we followed all Swedish married individuals aged 60 to 100 years (n = 1,783,035), from 1987 to 2002. Data are presented as mean with 95% confidence interval (CI). Results During the follow-up period, 21,305 hip fractures among widows and 6538 hip fractures among widowers were noted. The hazard ratio (HR) for hip fracture in widows compared with married women was 1.34 (95% CI 1.31 to 1.37) and for widowers compared with married men 1.32 (95% CI 1.29 to 1.35). The HR for hip fracture in the first 6 months after death of a spouse was in widows compared with married women 1.62 (95% CI 1.53 to 1.71) and in widowers compared with married men 1.84 (95% CI 1.68 to 2.03). The elevated risk was especially prominent in young widowers in the age range 60-69 years. During the first 6 months they showed a HR of 2.76 (95% CI 1.66 to 4.58) for a hip fractvure compared with age matched married men. Widows aged 60-69 years showed a HR of 1.59 (95% CI 1.26 to 1.99) compared with age matched married women. Conclusion Our observation of a higher hip fracture risk in both genders in connection with the death of a spouse indicates a possible effect of bereavement on frailty.

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