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Sheep are among the earliest domesticated livestock species, with a wide variety of breeds present today. However, it remains unclear how far back this diversity goes, with formal documentation only dating back a few centuries. North European short-tailed (NEST) breeds are often assumed to be among the oldest domestic sheep populations, even thought to represent relicts of the earliest sheep expansions during the Neolithic period reaching Scandinavia <6,000 years ago. This study sequenced the genomes (up to 11.6X) of five sheep remains from the Baltic islands of Gotland and Åland, dating from the Late Neolithic (∼4,100 cal BP) to historical times (∼1,600 CE). Our findings indicate that these ancient sheep largely possessed the genetic characteristics of modern NEST breeds, suggesting a substantial degree of long-term continuity of this sheep type in the Baltic Sea region. Despite the wide temporal spread, population genetic analyses show high levels of affinity between the ancient genomes and they also exhibit relatively high genetic diversity when compared to modern NEST breeds, implying a loss of diversity in most breeds during the last centuries associated with breed formation and recent bottlenecks. Our results shed light on the development of breeds in Northern Europe specifically as well as the development of genetic diversity in sheep breeds, and their expansion from the domestication center in general. [ABSTRACT FROM AUTHOR]

Objectives: In order to understand contacts between cultural spheres in the third millennium BC, we investigated the impact of a new herder culture, the Battle Axe culture, arriving to Scandinavia on the people of the sub‐Neolithic hunter‐gatherer Pitted Ware culture. By investigating the genetic make‐up of Pitted Ware culture people from two types of burials (typical Pitted Ware culture burials and Battle Axe culture‐influenced burials), we could determine the impact of migration and the impact of cultural influences. Methods: We sequenced and analyzed the genomes of 25 individuals from typical Pitted Ware culture burials and from Pitted Ware culture burials with Battle Axe culture influences in order to determine if the different burial types were associated with different gene‐pools. Results: The genomic data show that all individuals belonged to one genetic population—a population associated with the Pitted Ware culture—irrespective of the burial style. Conclusion: We conclude that the Pitted Ware culture communities were not impacted by gene‐flow, that is, via migration or exchange of mates. These different cultural expressions in the Pitted Ware culture burials are instead a consequence of cultural exchange. [ABSTRACT FROM AUTHOR]

High quality reference genomes are an important resource in genomic research projects. A consequence is that DNA fragments carrying the reference allele will be more likely to map successfully, or receive higher quality scores. This reference bias can have effects on downstream population genomic analysis when heterozygous sites are falsely considered homozygous for the reference allele. In palaeogenomic studies of human populations, mapping against the human reference genome is used to identify endogenous human sequences. Ancient DNA studies usually operate with low sequencing coverages and fragmentation of DNA molecules causes a large proportion of the sequenced fragments to be shorter than 50 bp—reducing the amount of accepted mismatches, and increasing the probability of multiple matching sites in the genome. These ancient DNA specific properties are potentially exacerbating the impact of reference bias on downstream analyses, especially since most studies of ancient human populations use pseudo-haploid data, i.e. they randomly sample only one sequencing read per site. We show that reference bias is pervasive in published ancient DNA sequence data of prehistoric humans with some differences between individual genomic regions. We illustrate that the strength of reference bias is negatively correlated with fragment length. Most genomic regions we investigated show little to no mapping bias but even a small proportion of sites with bias can impact analyses of those particular loci or slightly skew genome-wide estimates. Therefore, reference bias has the potential to cause minor but significant differences in the results of downstream analyses such as population allele sharing, heterozygosity estimates and estimates of archaic ancestry. These spurious results highlight how important it is to be aware of these technical artifacts and that we need strategies to mitigate the effect. Therefore, we suggest some post-mapping filtering strategies to resolve reference bias which help to reduce its impact substantially. [ABSTRACT FROM AUTHOR]

Archaeogenomic research has proven to be a valuable tool to trace migrations of historic and prehistoric individuals and groups, whereas relationships within a group or burial site have not been investigated to a large extent. Knowing the genetic kinship of historic and prehistoric individuals would give important insights into social structures of ancient and historic cultures. Most archaeogenetic research concerning kinship has been restricted to uniparental markers, while studies using genome-wide information were mainly focused on comparisons between populations. Applications which infer the degree of relationship based on modern-day DNA information typically require diploid genotype data. Low concentration of endogenous DNA, fragmentation and other post-mortem damage to ancient DNA (aDNA) makes the application of such tools unfeasible for most archaeological samples. To infer family relationships for degraded samples, we developed the software READ (Relationship Estimation from Ancient DNA). We show that our heuristic approach can successfully infer up to second degree relationships with as little as 0.1x shotgun coverage per genome for pairs of individuals. We uncover previously unknown relationships among prehistoric individuals by applying READ to published aDNA data from several human remains excavated from different cultural contexts. In particular, we find a group of five closely related males from the same Corded Ware culture site in modern-day Germany, suggesting patrilocality, which highlights the possibility to uncover social structures of ancient populations by applying READ to genome-wide aDNA data. READ is publicly available from . [ABSTRACT FROM AUTHOR]

Summary The origins and genetic affinity of the aboriginal inhabitants of the Canary Islands, commonly known as Guanches, are poorly understood. Though radiocarbon dates on archaeological remains such as charcoal, seeds, and domestic animal bones suggest that people have inhabited the islands since the 5 th century BCE [ 1–3 ], it remains unclear how many times, and by whom, the islands were first settled [ 4, 5 ]. Previously published ancient DNA analyses of uniparental genetic markers have shown that the Guanches carried common North African Y chromosome markers (E-M81, E-M78, and J-M267) and mitochondrial lineages such as U6b, in addition to common Eurasian haplogroups [ 6–8 ]. These results are in agreement with some linguistic, archaeological, and anthropological data indicating an origin from a North African Berber-like population [ 1, 4, 9 ]. However, to date there are no published Guanche autosomal genomes to help elucidate and directly test this hypothesis. To resolve this, we generated the first genome-wide sequence data and mitochondrial genomes from eleven archaeological Guanche individuals originating from Gran Canaria and Tenerife. Five of the individuals (directly radiocarbon dated to a time transect spanning the 7 th –11 th centuries CE) yielded sufficient autosomal genome coverage (0.21× to 3.93×) for population genomic analysis. Our results show that the Guanches were genetically similar over time and that they display the greatest genetic affinity to extant Northwest Africans, strongly supporting the hypothesis of a Berber-like origin. We also estimate that the Guanches have contributed 16%–31% autosomal ancestry to modern Canary Islanders, here represented by two individuals from Gran Canaria. [ABSTRACT FROM AUTHOR]

We have sampled five out of the eleven previously identified human specimens and some faunal remains from the Plovers Lake site in the Cradle of Humankind, South Africa, for ancient DNA. We were successful in obtaining positive results for three of the human individuals and three 'buffalo' teeth. Based on ages obtained for flowstone and one bovid tooth, the site was interpreted previously as a hominin-bearing Middle Stone Age site of more than 60 000 years old. Our work, however, revealed that not all the material accumulated during the Pleistocene. Instead, the sampled humans and bovids most likely represent a Bantu-speaking Iron Age population (mtDNA haplogroup L3d) and their Nguni cattle. Newly obtained radiocarbon dates confirmed that these remains are probably no older than the last 500 years bp. This study demonstrates the usefulness of inter-disciplinary investigation into the human past, and the depositional and stratigraphic complexities that researchers in the Cradle of Humankind need to contend with before interpreting their assemblages. [ABSTRACT FROM AUTHOR]

Summary The impact of human mobility on the northern European urban populations during the Viking and Early Middle Ages and its repercussions in Scandinavia itself are still largely unexplored. Our study of the demographics in the final phase of the Viking era is the first comprehensive multidisciplinary investigation that includes genetics, isotopes, archaeology, and osteology on a larger scale. This early Christian dataset is particularly important as the earlier common pagan burial tradition during the Iron Age was cremation, hindering large-scale DNA analyses. We present genome-wide sequence data from 23 individuals from the 10th to 12th century Swedish town of Sigtuna. The data revealed high genetic diversity among the early urban residents. The observed variation exceeds the genetic diversity in distinct modern-day and Iron Age groups of central and northern Europe. Strontium isotope data suggest mixed local and non-local origin of the townspeople. Our results uncover the social system underlying the urbanization process of the Viking World of which mobility was an intricate part and was comparable between males and females. The inhabitants of Sigtuna were heterogeneous in their genetic affinities, probably reflecting both close and distant connections through an established network, confirming that early urbanization processes in northern Europe were driven by migration. Highlights • A case study reveals mobility between population clusters within the Viking world • Archaeology, osteology, genetics, and isotopes highlight nuanced migration patterns • Local, regional, and long-distance immigrants are identified in the town of Sigtuna • We report 23 new ancient human genomes from the 10th to the 12th century CE Sweden Krzewińska et al. report genetic and isotopic data from 23 Viking Age individuals from Sweden. By complementing archaeological and osteological data with paleogenetic and isotope data, a high level of mobility within the early medieval world can be detected, revealing the cosmopolitan nature of the late Viking towns. [ABSTRACT FROM AUTHOR]