Biological and substitute parents in Beaker period adult-child graves

Joint inhumations of adults and children are one of the most intriguing aspects of the shift from collective to single burial rites in third millennium BC Western Eurasia. Here, we revisit two exceptional Beaker period adult-child graves using ancient DNA: Altwies in Luxembourg and Dunstable Downs in Britain. We present evidence that close blood relations, including a biological mother and her son at Altwies, were buried together. Ancestry modelling and patterns of shared IBD segments between the individuals examined and contemporary genomes from Central and Northwest Europe further highlight the continental connections of Bronze Age Britain. The practice of paired burial indicates the key role played by biological relationships in structuring third millennium BC social systems and burial practices. We propose that extended family, such as a paternal aunt at Dunstable Downs, could act as substitute parents to the child in the grave. Hypotheses are explored to explain the simultaneous inhumation of adults and children. While violence cannot be excluded, interpretations such as enemy raids fail to account for the pervasiveness of the phenomenon, as evidenced by a representative sample of 117 adult-child graves from 78 sites across Eurasia, all dating to the third and second millennia BC.