Ancient Iberian cattle
Cattle has been a valuable food resource since prehistory; indeed, this species accounts for the highest biomass on the planet today. Since the initial expansion of domestic cattle into Europe during the Neolithic period, taurine cattle (Bos taurus) and their wild ancestor, the aurochs (B. primigenius), had overlapping ranges leading to ample opportunities for intentional and unintentional hybridization. We sequenced 24 Bos remains from Northern Iberia dating from the Mesolithic to the Roman period. This archaeogenomic dataset allows us to investigate the extent of domestic-wild hybridization over time providing insight into the species' behavior and human management by aligning changes with cultural and genomic transitions in the archaeological record. Our results show frequent hybridization during the Neolithic and Chalcolithic, likely reflecting a mix of hunting and herding or relatively unmanaged domestic herds, with mostly male aurochs and female domestic cattle involved in hybridization. Aurochs ancestry remains relatively constant from about 4000 years ago, probably due to herd management and selection against hybrids, coinciding with other cultural transitions. The constant level of wild ancestry (~20%) continues into modern western European breeds including the Spanish Lidia cattle which is used in bullfighting but does not display genome-wide elevated levels of aurochs ancestry. This study takes a genomic glance at the impact of human actions and wild introgression in the establishment of cattle as one of the most important domestic species today.