Horse evolved genetically as a result of its use by humans

The domestication of horses has caused significant physiological changes in this animal, arising from the use that humans made of them, reveals an international genetic study. Scientists decoded the genome of ancient horses originating in Russia from fossil bones from 16, 000 to 43, 000 years old, an era long before the domestication of these horses, dating back 5, 500 years.

They then compared these ancient genomes with those of five modern species of domesticated horses, as well as the Przewalski horse genome, the only untouched wild breed discovered in 1879 in Mongolia. These comparisons showed that domesticated horses share more genetic similarities with their wild ancestors than with the still living Przewalski.

The study authors estimate that between 13% and 60% of today's horse genome comes from extinct species. This means that domesticated breeds are all descended, at least in part, from former missing equine populations, the authors concluded in their work published in the annals of the American Academy of Sciences (PNAS).

Scientists have also identified the group of genes that most influenced domestication, particularly those linked to muscle formation, limbs, joints, and cardiac system development. This illustrates the physiological adaptations that have apparently been the result of humans' use of horses over the centuries.

Loss of diversity

The researchers also found the genetic mutations linked to the horse's social behavior and learning abilities, which also reflected the animal's taming process. But the genome of modern horses still contains a great deal of harmful genetic mutations as a result of domestication, which has meant a great loss of genetic diversity and the extinction of wildlife.

"We (humans) probably had an influence on genes whose mutations made it possible to turn the horse into a transport animal, " said Professor Beth Shapiro, head of the University of California paleontology laboratory at Santa Cruz and one of the lead authors of the study.

"We were able to identify the genes that control the horse's behavior and its response to fear, " said Ludovic Orlando, a professor at the University of Copenhagen Center for Geogenetics. "These genes could be the ones that turned wild horses into docile animals, as we know them today, " he added. But the whole process of domestication comes at a cost if it causes an accumulation of genetic mutations that undermine diversity. This phenomenon has been observed in cultivated plants, such as rice, and in other animals, such as dogs.

The domestication of the horse allowed revolutionizing civilization and human societies, facilitating the transportation of people and goods, as well as the spread of ideas, languages ​​and religions. Horses also revolutionized warfare with the advent of carriages and cavalry. In addition to the battlefield, they also facilitated agriculture, the researchers added.

By Jean-Louis Santini - Washington, United States

Via InAbstract