Cattle (Bos taurus) play an important role in the life of humans in the Iberian Peninsula not just as a food source but also in cultural events. When domestic cattle were first introduced to Iberia, wild aurochs (Bos primigenius) were still present, leaving ample opportunity for mating (whether intended by farmers or not). Using a temporal bioarchaeological dataset covering eight millennia, we trace gene flow between the two groups. Our results show frequent hybridisation during the Neolithic and Chalcolithic, likely reflecting a mix of hunting and herding or relatively unmanaged herds, with mostly male aurochs and female domestic cattle involved. This is supported by isotopic evidence consistent with ecological niche sharing, with only a few domestic cattle possibly being managed. The proportion of aurochs ancestry in domestic cattle remains relatively constant from about 4000 years ago, probably due to herd management and selection against first generation hybrids, coinciding with other cultural transitions. The constant level of wild ancestry (~20%) continues into modern Western European breeds including Iberian cattle selected for aggressiveness and fighting ability. This study illuminates the genomic impact of human actions and wild introgression in the establishment of cattle as one of the most important domestic species today.
Keywords: Bos primigenius; Bos taurus; Iberia; ancient DNA; domestication; evolutionary biology; genetics; genomics; hybridisation.
For over five thousand years, domesticated cows and oxen in the Iberian Peninsula lived alongside their wild counterparts, the aurochs. These large and aggressive animals, from which modern European cattle descends, only went extinct during the 17th century. Genetic evidence points to aurochs and livestock having interbred during their long coexistence; when and how these mixing events took place, however, remains unclear. Details regarding the management of ancient herds are also missing. To address these questions, Günther et al. analysed the DNA extracted from ancient bovine bones sampled at four Iberic archaeological sites. This revealed that wild aurochs and cattle frequently interbred during the last 8,000 years. Mating principally took place between male aurochs and domesticated cows but slowed down after 4,000 years, resulting in modern cattle having inherited about 20% of genes from their wild relatives. This percentage was consistent across various breeds, including one renowned for its aggressivity and which has been selected for centuries for Spanish bullfighting. Additional bone analyses revealed that aurochs and ancient cattle shared comparable diets composed primarily of wild vegetation. Only some domestic animals showed signs of having been fed crops. These findings help us understand how modern cattle breeds came to be. The genes they inherited from aurochs may help them survive harsh environmental conditions, such as extreme heat or diseases. In the future, researchers could use this knowledge to refine breeding programs.
© 2024, Gunther et al.