Genetic admixture between East and West European Gravettian-associated populations in Western Europe before the Last Glacial Maximum

Modern humans first settled in Europe at least 45,000 years ago. However, limited genomic data from individuals dating between 45,000 and 20,000 years ago still restricts our understanding of population dynamics and admixture during the Upper Palaeolithic. Before the Last Glacial Maximum (LGM, 26.5–19 cal kya), Gravettian culture-associated populations were widespread and genetically diverse, comprising at least two distinct genetic groups, referred to as the Fournol and Věstonice clusters. We present genome-wide data from three Gravettian-associated individuals: two from cave sites in the Franco-Cantabrian region (Chufín and Isturitz) and one from Italy (Ostuni1b). These data reveal previously undetected gene flow linking the ancestry of 34,000-year-old individuals from Sungir (Russia) to Gravettian individuals from Western Europe, challenging the prevailing model of population continuity from the Aurignacian to the Solutrean. As osseous remains are scarce for this time period, DNA from sediments deposited by ancient humans opens a new possibility to obtain genomic data. We thus examine sedimentary DNA from Solutrean Layer 122 at El Mirón Cave (Cantabria, ∼22,000 cal BP), recovering approximately 16,000 human SNPs, among the highest yields reported from a Palaeolithic context. Generating these data required over 1.15 billion sequencing reads, illustrating both the potential of sediment DNA for autosomal analysis and the technical challenges of the approach.