Geneticists from Trinity College Dublin, alongside an international research team, have uncovered the prehistory of the aurochs, one of the most significant animals in early human life and art. By analyzing 38 genomes from ancient aurochs bones, dated across 50,000 years and spanning regions from Siberia to Britain, the team has provided new insights into the evolution and eventual domestication of these impressive creatures. This research, recently published in Nature, highlights the diverse genetic lineage of the aurochs and its transformation into modern cattle, whose descendants now constitute roughly a third of the world’s mammalian biomass.
Aurochs once roamed freely across Europe, Asia, and Africa, and were frequently depicted in ancient cave paintings, reflecting their prominence in the lives of early humans. These powerful animals were eventually domesticated, giving humanity a reliable source of muscle power, meat, and milk—a domestication process that has left a lasting impact on our world today.
Dr. Conor Rossi of Trinity College, the study’s first author, points out that the extinction of aurochs around 400 years ago left much of their evolutionary history unknown. With the help of ancient DNA sequencing, however, researchers are now able to reconstruct this lost past. This technology has allowed scientists to glimpse the genetic diversity that once flourished among wild aurochs and has enhanced our understanding of how domesticated cattle emerged from these ancient animals.
Though the fossil record of aurochs in Europe extends back roughly 650,000 years, the new study shows that aurochs populations across Europe and Asia have a much more recent shared ancestry, likely around 100,000 years ago. This genetic similarity suggests that a significant migration or replacement event occurred, with populations from a southern Asian region moving across Eurasia. Interestingly, traces of earlier genetic ancestry remained in some European aurochs, indicating that this migration did not completely replace the original populations.
Dr. Mikkel Sinding, a co-author and postdoctoral researcher at the University of Copenhagen, explains that rather than being one homogeneous population, the aurochs in Europe actually represented at least three genetically distinct groups: one in Western Europe, one in Italy, and another in the Balkans. This discovery reveals a far greater diversity among wild aurochs than scientists previously understood, challenging the idea that European aurochs existed as a single population.
Climate change also played a significant role in shaping aurochs evolution, as revealed through their genetic data. Around the beginning of the last ice age, roughly 100,000 years ago, populations in Europe and northern Asia began to diverge genetically. These groups remained separated throughout the glacial period and only mixed again when the climate warmed. During the ice age, the estimated population size of aurochs plummeted, with European herds experiencing a greater loss of genetic diversity as they retreated into southern refugia before later re-expanding across the continent.
One of the most significant drops in genetic diversity occurred approximately 10,000 years ago in southwest Asia, where early humans domesticated the first cattle from aurochs in the northern Fertile Crescent. Genetic analysis shows that only a small number of maternal lineages survived this domestication process, a fact evident in the mitochondrial DNA inherited from female ancestors. This suggests that early domestication involved only a small group of wild aurochs, likely due to the considerable challenges posed by capturing and taming such formidable animals.
Professor Dan Bradley, who led the study from Trinity’s School of Genetics and Microbiology, suggests that the first domestication of aurochs likely took place with just a handful of animals, given their strength and potential danger. Although Julius Caesar famously compared the aurochs to an elephant, this may have been an exaggeration; nonetheless, the wild ox was undoubtedly a fearsome creature, and taming it would have been a risky venture.
As these early domesticated cattle spread with human herders to different regions, they interbred with local wild aurochs bulls, which introduced additional genetic diversity into their gene pool. This interbreeding preserved remnants of four distinct preglacial aurochs lineages that are still present in domestic cattle today.
This groundbreaking study highlights the complex prehistory of aurochs and the dynamic processes that shaped both the wild and domesticated populations over tens of thousands of years. Through this research, scientists are gaining a deeper appreciation for the genetic legacy of the aurochs, which continues to influence modern cattle and underscores the profound impact these ancient animals have had on human history.
Source: Trinity College Dublin