Genetic transitions in the Neolithic and Bronze Age at Mas d'en Boixos (Catalonia, Spain)

Mas d'en Boixos (MDB) in Catalonia, Spain, is a key prehistoric site spanning the Early Neolithic to the Late Iron Age, approximately 7,500 to 2,200 years ago, aligning with two major cultural and genetic transitions in Europe: the Neolithic shift from hunter-gatherers to farmers and the Bronze Age migration of Pontic Steppe herders. This study analyses the genetic profiles of 25 new individuals from MDB, recovering 10 complete mitogenomes and 8 genome-wide datasets from Middle Neolithic and Early Bronze Age individuals, alongside data from 3 previously published Iron Age individuals. Our results revealed a maternal first-degree relationship between two Middle Neolithic individuals buried together. They presented Western Hunter-Gatherer and Anatolian Farmer ancestries and retained low Upper Palaeolithic Magdalenian ancestry. In contrast, six Early Bronze Age individuals buried in close proximity exhibited genetic continuity with an additional Steppe-related ancestry. These individuals carried distinct mitochondrial lineages, showed three third-degree relationships and all males shared the same Y-chromosome lineage, evidencing extended family-based collective burial practices in Eastern Iberia and a patrilocal society with possible female exogamy. We also found Eastern European mitochondrial lineages, proposing possible female migration, challenging the previously suggested male-driven Bronze Age transition in Iberia. Additionally, we also revealed a subtle southward gradient in Steppe-related ancestry across Iberia, with some of the lowest levels in Bronze Age Europe. Notably, we revealed for the first time a significant Mediterranean influence in Northeastern Bronze Age Iberia, which was absent in the Neolithic and Iron Age at MDB, suggesting dynamic interactions across the Mediterranean.