Corded Ware Culture (CWC) Genetics

Kinship and Consanguinity.
Analyses of ancient genomes can provide detailed information on the kinship structures and social organization of past communities (8⇓–10). At Koszyce, mitochondrial DNA (mtDNA) analysis revealed the presence of six different maternal lineages, whereas analysis of the nonrecombining region of the Y chromosome showed that all males carried the same Y chromosome haplotype: I2a-L801 (Table 1). We then estimated genomic runs of homozygosity (ROH) and found that the Koszyce individuals were not particularly inbred. Although a slightly larger section of the Koszyce genomes is contained within ROH compared with typical modern European populations (SI Appendix, Fig. S7), this signal is mainly driven by an increased fraction of short ROH (<2 Mb), which is indicative of ancestral restrictions in population size rather than recent inbreeding. On the basis of genome-wide patterns of allelic identity-by-state (IBS), we computed kinship coefficients between all pairs of individuals and applied established cutoff values for possible kinship categories (Materials and Methods). We find that the Koszyce burial represents a large extended family connected via several first- and second-degree relationships (Fig. 3 and SI Appendix, Fig. S9).



Fig. 3.
Kinship. (A) Artistic reconstruction of the Koszyce mass burial based partly on phenotypic traits inferred from the ancient genomes (reconstruction by Michał Podsiadło); (B) Schematic representation of the burial and pedigree plots showing kinship relations between the Koszyce individuals inferred from genetic data. (C) kinship network based on kinship coefficients inferred from IBS scores for pairs of Koszyce individuals showing first- and second-degree relationships. Kinship coefficients and R scores are reported in Dataset S7 and plotted in SI Appendix, Fig. S9.

Overall, we identified four nuclear families in the grave, which are for the most part represented by mothers and their children (Fig. 3). Closely related kin were buried next to each other: a mother was buried cradling her child, and siblings were placed side by side. Evidently, these individuals were buried by people who knew them well and who carefully placed them in the grave according to familial relationships. For example, individual 14, the oldest individual in the grave, was buried close to her two sons (individuals 5 and 15), whereas individual 8, a 30–35-y-old woman, was buried with her teenage daughter (individual 9) and 5-y-old son (individual 13). Using genome-wide patterns of IBS, we were also able to reconstruct more complex relationships: individuals 5, 10, 11, and 15 all appear to be brothers, and yet they do not have the same mother (individual 14 is the mother of individuals 5 and 15, but not 10 and 11), suggesting that they might be half-brothers. However, all four of them share the same mitochondrial DNA haplotype, suggesting that their mothers might also have been related.

Interestingly, the older males/fathers are mostly missing from the grave, suggesting that it might have been them who buried their kin. The only father present in the grave is individual 10, whose partner and son are placed together opposite him in the grave. In addition, there is a young boy (individual 7), aged 2–2.5 y, whose parents are not in the grave, but he is placed next to other individuals to whom he is closely related through various second-degree relationships. Finally, there is individual 3, an adult female, who does not seem to be genetically related to anyone in the group. However, her position in the grave close to individual 4, a young man, suggests that she may have been as close to him in life as she was in death. These biological data and burial arrangements show that the social relationships held to be most significant in these societies were identical with genetic and reproductive relationships. However, they also demonstrate that nuclear families were nested in larger, extended family groups, either permanently or for parts of the year.



Social Organization, Residence Patterns, and Subsistence Strategies.
The presence of unrelated females and related males in the grave is interesting because it suggests that the community at Koszyce was organized along patrilineal lines of descent, adding to the mounting evidence that this was the dominant form of social organization among Late Neolithic communities in Central Europe (11, 12). Usually, patrilineal forms of social organization go hand in hand with female exogamy (i.e., the practice of women marrying outside their social group). Indeed, several studies (11, 12) have shown that patrilocal residence patterns and female exogamy prevailed in several parts of Central Europe during the Late Neolithic. At Koszyce, there is no clear difference in enamel 87Sr/86Sr ratios between males and females (SI Appendix, Fig. S6) that would suggest that the females are nonlocal. However, the high diversity of mtDNA lineages, combined with the presence of only a single Y chromosome lineage, is certainly consistent with a patrilocal residence system.

Social organization is most often aligned with settlement and subsistence patterns, and several studies (13⇓–15) suggest that Globular Amphora communities and other related groups specialized in animal husbandry, often with a main focus on cattle, and that they moved around the landscape to seek new pastures for their animals at different times of the year (see SI Appendix, section 1 for a more detailed discussion). This form of mobility is likely to have included fission-fusion dynamics in which a larger social unit, similar to the extended family, would split up into smaller groups, perhaps nuclear families, for certain purposes and parts of the year (16). This dynamic could explain the relatively high variation we observe in the 87Sr/86Sr isotope signatures at Koszyce. Similar to strongly patrilineal modes of social organization, such pastoral economic strategies have often been linked to Corded Ware groups that introduced steppe genetic ancestry into Europe (7, 17), and the two (social organization and economic strategy) are probably linked: Pastoral ways of life involve a high level of mobility within vaguely defined territories and with the groups’ main economic capital, their animal herds, exposed across the landscape, and thus harbor a significant potential for conflict with neighboring groups. One ethnographically known cultural response to this situation is to adopt an aggressive strategy toward competing groups in which male dominance, including patrilineal kin alliance, and warrior-like values prevail (18). Although we cannot be certain that the people at Koszyce shared these values, we show that they were organized around patrilineal descent groups, demonstrating that this form of social organization was already present in communities before the expansion of the Corded Ware complex in Central and Eastern Europe (13, 14).

Intergroup Conflict and Violence.
All individuals buried in the mass grave at Koszyce exhibit extensive evidence of perimortem injuries (SI Appendix, section 3). The most common injuries are cranial fractures (SI Appendix, Fig. S2), which indicate that the individuals were killed by blows to the head. Overall, the nature of the injuries and the near absence of so-called parry fractures (i.e., injuries sustained to the upper limbs) suggest that the individuals were captured and executed, rather than killed in hand-to-hand combat. The evidence for violence at Koszyce fits within a wider pattern of extensive, frequent violence during specific stages in European prehistory (19). Evidence from the Neolithic indicates that lethal violence and massacres prevailed during periods of population pressure, competition over resources, and/or the expansion of new groups into already-occupied territories (20, 21), a pattern also observed in well-known cases from the New World (22).

Neolithic cases of intergroup violence appear to fall into one of two categories, either targeting whole communities (11, 20) or aimed specifically at males from competing groups (21). The former strategy presumably aims at eradicating a competing group from a given territory, whereas in the latter case, it may be assumed that the women and/or children are taken as captives, a practice that is well documented ethnographically and historically for prestate societies (23). Although alternative scenarios (e.g., ritualistic violence or familicide) cannot be ruled out, it seems most plausible that the massacre at Koszyce falls in the former category. The fact that most adult males of the group are missing from the grave most likely reflects that they were away (or fled) when the raid occurred, leaving the remaining group vulnerable.

Although it is impossible to identify the culprits of the massacre that took place at Koszyce around 2880–2776 BCE, it is interesting to note that it occurred right around the time when the Corded Ware complex started to spread rapidly across large parts of Central Europe, and it seems plausible that the group from Koszyce fell victim to some violent intergroup conflict related to the territorial expansion of Corded Ware groups or another competing group in the area. If the general interaction between Globular Amphora people and neighboring, steppe-related cultures (including early Corded Ware) was primarily hostile, it would explain why Globular Amphora individuals carry no steppe ancestry and, in part, why Europe experienced such a dramatic reduction in Neolithic genomic ancestry at this time (7, 17).

PNAS first published May 6, 2019