A new genome-wide analysis by Marta Pereira Verdugo and colleagues uncovers the complex origins of domestic cattle (Bos taurus), demonstrating why it has been difficult to untangle these origins from studies of modern breeds. Cattle were first domesticated around 10,500 years ago from the extinct Eurasian auroch, Bos primigenius, in northern Mesopotamia. By comparing the auroch genome to the genomes of 67 ancient Bos taurus specimens from archaeological sites in the Near East, Verdugo et al. conclude that the first domesticated cattle populations had diverse origins among aurochs, with multiple strains of wild auroch contributing to a growing population of domesticated cows. Around 4,000 years ago, Bos taurus populations across the region received a rapid and widespread influx of primarily male genetic material from the zebu (Bos indicus) from the Indus Valley. This genomic shift occurred during a multi-century drought, and the drought-adapted zebu may have been brought into the domesticated cattle populations as a way to keep herds thriving under arid conditions, the researchers say.