Ancient DNA brings to life the story of the iconic aurochs

Oct. 31 () –

An international team of geneticists has deciphered the prehistory of the aurochs, analyzing 38 genomes extracted from bones dating back 50 millennia. and that extend from Siberia to Great Britain.

These animals were the center of attention of some of the most emblematic works of art from the early days of human beings.

Aurochs roamed Europe, Asia and Africa for hundreds of thousands of years. Adorned like paintings on the walls of many caves, Their domestication to create livestock provided us with a source of muscle, meat and milk. Such was the influence of this domestication that today their descendants constitute a third of the world’s mammal biomass.

Dr. Conor Rossi of Trinity College Dublin, first author of the Nature paper, said in a statement: “The aurochs They became extinct approximately 400 years ago, which left much of its evolutionary history a mystery.

“However, through ancient DNA sequencing, we have gained detailed information about the diversity that once thrived in nature, as well as improving our understanding of domestic livestock.

Although aurochs fossils found in Europe date back to 650,000 years ago, around the time archaic species of humans appeared on the continent, animals from the eastern and western ends of Eurasia share a much more recent common ancestry, pointing to to a replacement about 100,000 years ago, probably by migrations from a South Asian homeland.

In an echo of human prehistory, this replacement was not complete, and traces of earlier ancestry survived in European aurochs.

Mikkel Sinding, co-author and postdoctoral researcher stated: “We normally think of the European aurochs as a common form or type, but our analyzes suggest that there were three distinct populations of aurochs in Europe alone: ​​a Western European, an Italian and a Balkan. “Therefore, there was greater diversity in wild forms than we had ever imagined.”

Interestingly, climate change also wrote its signature on the aurochs’ genomes in two ways:

First, the European and North Asian genomes split and diverged at the beginning of the last ice age, about 100,000 years ago, and did not appear to mix until the world warmed again at the end. And second, genome-estimated population sizes decreased in the glacial period, with a tougher period endured by European herds.

They lost most of their diversity when they retreated to separate refuges in southern parts of the continent before repopulating it again later.

The most pronounced drop in genetic diversity occurs between the period when the aurochs of southwest Asia were domesticated in the northern Fertile Crescent, just over 10,000 years ago, to provide the first livestock. Surprisingly, only a handful of maternal lineages (as seen through mitochondrial DNA that is passed through mothers to their offspring) are passed 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 very dangerous beast and This suggests that their first capture and domestication must have occurred with very few animals.“said Dan Bradley, professor at Trinity’s School of Genetics and Microbiology, who led the study.

“However, the narrow genetic base of the first cattle increased when they first traveled with their herders to the west, east and south. It is clear that there was early and widespread mating with wild aurochs males, leaving a legacy of all four ancestries separated from preglacial aurochs that persist among today’s domestic livestock.