eLife assessment
Using genomic data from ancient and modern samples, this important study investigates the genomic history of cattle in Iberia, focusing on the admixture between domestic cattle and their wild ancestors, aurochs. The authors present solid evidence for interbreeding between domestic cattle and wild aurochs since the Neolithic period, although the extent, sex bias, and directionality of genetic flow over time remain highly unclear. The authors also show that the aurochs ancestry in cattle stabilized at ~20% since ~4000 years ago and continues into modern breeds, including the Lidia breed that is bred for aggressiveness and used in bullfighting. The work will be of interest to evolutionary biologists and quantitative geneticists who seek to understand the genomic history and genetic basis of trait variation of domesticated animals.