We present a high-resolution cross-disciplinary analysis of kinship structure and social institutions in two Late Copper Age Bell Beaker culture cemeteries of South Germany containing 24 and 18 burials, of which 34 provided genetic information. By combining archaeological, anthropological, genetic and isotopic evidence we are able to document the internal kinship and residency structure of the cemeteries and the socially organizing principles of these local communities. The buried individuals represent four to six generations of two family groups, one nuclear family at the Alburg cemetery, and one seemingly more extended at Irlbach. While likely monogamous, they practiced exogamy, as six out of eight non-locals are women. Maternal genetic diversity is high with 23 different mitochondrial haplotypes from 34 individuals, whereas all males belong to one single Y-chromosome haplogroup without any detectable contribution from Y-chromosomes typical of the farmers who had been the sole inhabitants of the region hundreds of years before. This provides evidence for the society being patrilocal, perhaps as a way of protecting property among the male line, while in-marriage from many different places secured social and political networks and prevented inbreeding. We also find evidence that the communities practiced selection for which of their children (aged 0–14 years) received a proper burial, as buried juveniles were in all but one case boys, suggesting the priority of young males in the cemeteries. This is plausibly linked to the exchange of foster children as part of an expansionist kinship system which is well attested from later Indo-European-speaking cultural groups.

32We present a high-resolution cross-disciplinary analysis of kinship structure and social institutions in 33 two Late Copper Age Bell Beaker culture cemeteries of South Germany containing 24 and 18 burials, 34 of which 34 provided genetic information. By combining archaeological, anthropological, genetic and 35 isotopic evidence we are able to document the internal kinship and residency structure of the 36 cemeteries and the socially organizing principles of these local communities. The buried individuals 37 represent four to six generations of two family groups, one nuclear family at the Alburg cemetery, 38 and one seemingly more extended at Irlbach. While likely monogamous, they practiced exogamy, as 39 six out of eight non-locals are women. Maternal genetic diversity is high with 23 different 40 mitochondrial haplotypes from 34 individuals, whereas all males belong to one single Y-chromosome 41 haplogroup without any detectable contribution from Y-chromosomes typical of the farmers who 42 had been the sole inhabitants of the region hundreds of years before. This provides evidence for the 43 society being patrilocal, perhaps as a way of protecting property among the male line, while in-44 marriage from many different places secured social and political networks and prevented inbreeding. 45We also find evidence that the communities practiced selection for which of their children (aged 0-14 46 years) received a proper burial, as buried juveniles were in all but one case boys, suggesting the 47 priority of young males in the cemeteries. This is plausibly linked to the exchange of foster children 48 as part of an expansionist kinship system which is well attested from later Indo-European-speaking 49 cultural groups. 50 51Recent genetic research has made it clear that the third millennium BC was a period of large-scale 53 migrations from the Caspian-Pontic steppe towards central and, later, western Europe, leading first 54 to the formation of the Corded Ware and then the Bell Beaker complexes [1, 2, 3]. This is also 55 evidenced in a shared burial ritual in Central Europe, characterized by individual burials and strict 56 3 differentiation between males and females in the orientation of the body [4]. The genetic admixture 57 that resulted from these migrations still characterizes modern European populations, just as it is very 58 likely that predecessors of one or several Indo-European languages spoken in Europe today were 59 carried by these migrations [5,6]. 60 61 However, it is still not well understood how it was possible for these populations to establish and 62 maintain their cultural, social and linguistic coherence over time. For the Corded Ware complex it has 63 been suggested that initial migrations were dominated by males, who married in women probably 64 from residing Neolithic populations [6, 7, 8, 9], although at present it is debated whether the genetic 65 evidence for male-dominated migrations contributing to these groups is compelling [10, 11]. There is 66 also evidence that the individual grou...

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