The oldest known ancestors of the domesticated ox have been discovered in the Indus Valley and the Fertile Crescent in Mesopotamia: these are the remains of the aurochs (Bos primigenius) dating back some 10,000 years. The research, published in the journal Nature and carried out by Trinity College in Dublin and the University of Copenhagen, involved Luca Pandolfi, a palaeontologist at the Department of Earth Sciences of the University of Pisa, who has long studied with the evolution and extinction of large continental mammals, also in relation to climate change.
Domesticated aurochs were animals quite similar to their wild counterparts, but slightly smaller, especially with less developed horns, indicating a greater degree of meekness. In fact, Julius Caesar in De Bello Gallico (6-28) describes wild aurochs as being slightly smaller than elephants, fast and particularly aggressive. Fossil remains show that wild aurochs could reach a height of just under two metres, weigh up to 1,000 kg and have horns over a metre long. They dominated the fauna of Eurasia and North Africa from around 650,000 years ago, only to suffer a sharp decline from the end of the Pleistocene, around 11,000 years ago, until their extinction in modern times. The last known specimen was killed in Poland in 1627.
“The study published in Nature is the first to analyse this species with the objective of understanding its evolutionary and genetic history through fossil remains found at several sites in Eurasia, including Italy, and North Africa,” says Luca Pandolfi.
Aurochs skull at the Natural History Museum of the University of Wroclaw, Poland (photo L. Pandolfi)
Ancient DNA samples were extracted from the finds, which included complete skeletons and well-preserved skulls. Their analysis then identified four distinct ancestral populations that responded differently to climate change and interaction with humans. In particular, European aurochs suffered a drastic decline in both population size and genetic diversity during the last Ice Age, around 20,000 years ago. Falling temperatures reduced their habitat and drove them into the Italian and Iberian peninsulas, from where they later recolonised the whole of Europe.
Cave paintings of Lascaux (France) with representations of aurochs. Image credit: Prof Saxx CC BY-SA 3.0
“During the Quaternary, an era that spans from 2.5 million years ago to the present day, aurochs were protagonists in the ecosystems of the past, demonstrating their ability to both shrink and expand their habitat in response to the climatic events that characterised this period,” concludes Pandolfi. “The bones of these majestic animals tell palaeontologists the story of the success, adaptation and decline of a species to whose extinction humans have also contributed and reveal the complexity and fragility of the relationships that link living organisms to the climate of our planet”.