Migrations facilitated the cultural diffusion of megaliths in Neolithic Europe

Around 6700 BP (years before present), Neolithic Europe saw the emergence of megalithic monuments in northern France, followed by a rapid spread to the rest of the continent1. However, whether this was driven by the transmission of ideas (cultural diffusion) or the movement of people remains debated. To test whether this spread coincided with population movements, we reconstructed the population history of the European Neolithic ([~]6500-4800 BP) by analysing genomic data from 2963 ancient individuals, including 46 unpublished genomes from megalithic and related contexts. To assess the alternative scenario whereby megaliths spread through contact networks, as expected under cultural diffusion, we integrated archaeological evidence with radiocarbon chronologies to reconstruct past trading networks. We identify northern France, where megaliths first emerged, as a zone of genetic admixture and cultural influence from the two major early Neolithic divisions: the Cardial of the Western Mediterranean and the Linear Pottery traditions of central Europe. From this admixed population, we uncover several migrations associated with the formation of the Funnel Beaker Culture in north-central Europe and the neolithisation of Scandinavia and the British Isles. We find that megaliths were spread exclusively within regions impacted by Cardial-related genetic ancestry, but only in the British Isles and Ireland did their emergence coincide with the time of the migration. The temporal delay between the migrations and the spread of megaliths elsewhere reveals that neither population movements nor cultural diffusion alone fully explains the geospatial distribution of the megalithic tradition. Rather, megaliths diffused across different Neolithic groups whose long-distance trade networks formed in the wake of earlier population movements. Our findings highlight the need to move beyond simplistic interpretations that present migrations or cultural diffusion as isolated events bringing technological and cultural innovations.