Geneticists from College, in collaboration with an international team of researchers, have deciphered the prehistory of aurochs through extensive DNA analysis.
Aurochs, a long-extinct species of bovine, feature heavily in early human art and roamed across Europe, Asia and Africa for hundreds of thousands of years.
The species was domesticated during the Neolithic period and its cattle provided humans during this period with a source of meat and milk. Today, the descendants of aurochs make up a third of the world’s mammalian biomass.
During the study, researchers analysed 38 genomes harvested from bones dating across 50 millennia and stretching from Siberia to Britain
Trinity geneticist and first author of the article recently published in the international journal Nature, Dr Conor Rossi, spoke about the team’s research
“The aurochs went extinct approximately 400 years ago, which left much of their evolutionary history a mystery. However, through the sequencing of ancient DNA, we have gained detailed insight into the diversity that once thrived in the wild as well as enhanced our understanding of domestic cattle.”
The study found new information regarding the genetic diversity of the auroch species, particularly amongst European aurochs
Dr Mikkel Sinding, co-author and postdoctoral researcher in the Department of Biology at the University of Copenhagen, said: “We normally think of the European aurochs as one common form or type, but our analyses suggest there were three distinct aurochs populations alone in Europe – a Western European, an Italian, and a Balkan. There was thus a greater diversity in the wild forms than we had ever imagined.”
Researchers also discovered that climate change had a notable impact on the auroch genomes.
The study found that European and north Asian genomes separated and diverged at the beginning of the last ice age, around 100,000 years ago, and did not seem to mix until the world warmed up again at its end. They also learned that genome-estimated population sizes dropped in the glacial period, with a notably hard time endured by European herds, who lost diversity as they retreated to southern parts of the continent.
The most pronounced drop in genetic diversity occurred between the period when the aurochs of southwest Asia were domesticated in the north of the Fertile Crescent, just over 10,000 years ago, to give the first cattle.
The research team found that only a handful of maternal lineages (as seen via mitochondrial DNA which is handed down via mothers to their offspring) come through this process into the cattle gene pool.
“Although Caesar exaggerated when he said it was like an elephant, the wild ox must have been a highly dangerous beast and this hints that its first capture and taming must have happened with only a very few animals,” said Dan Bradley, Professor in Trinity’s School of Genetics and Microbiology, who led the study.
“However, the narrow genetic base of the first cattle was augmented as they first travelled with their herders west, east and south. It is clear that there was early and pervasive mating with wild aurochs bulls, leaving a legacy of the four separate preglacial aurochs ancestries that persists among the domestic cattle of today.”
The study was funded by a European Research Council Advanced Grant “AncestralWeave” awarded to Professor Dan Bradley.
