According to a study published in Nature, horses were domesticated in the northern Caucasus, specifically in the Pontic-Caspian steppes, and from there conquered the rest of Europe and Asia in just a few centuries.
This long-standing mystery finally comes to an end thanks to an international team of 162 researchers from various fields, including linguistics, archaeology and paleogenetics. The team was led by Prof Ludovic Orlando, based at the Centre National de la Recherche Scientifique (CNRS) in France.
Prof Orlando and his team have been studying the domestication of horses for years. One of the sites analysed was in Botai, Central Asia, home to the oldest archaeological evidence of domesticated horses. Curiously, DNA analysis revealed that these 5500-year-old horses were not ancestors to modern horses. Other locations believed at one point to be the foci of domestication, such as Siberia, the Iberian Peninsula and Anatolia, also proved incorrect. “We knew that the time period between 4,000 to 6,000 years ago was critical, but no smoking guns could ever be found”, said Prof Orlando.
After these failed attempts, the team decided to extend their focus to the rest of Europe and Asia and analysed the genomes of 273 horses that lived between 50000 and 200 years BC. This information was then compared to the genomes of modern horses.
The analysis revealed that although this area was initially populated by several genetically distinct horse populations, by 2000BC, there was a significant change. A single genetic profile – previously only observed in the Pontic steppes – started spreading beyond its natural habitat. Eventually, these horses replaced the wild horse populations from Mongolia to the Atlantic in just a few centuries.
For the researchers, this sudden change was the result of domestication. “The genetic data also point to an explosive demography at the time, with no equivalent in the last 100,000 years”, added Prof Orlando. “This is when we took control over the reproduction of the animal and produced them in astronomic numbers.”
But why this species in particular? The answer also lies in their genome. Based on their DNA analysis, the team suggested that these horses were picked because they had a more docile behaviour and a more robust backbone. Both are crucial characteristics to ensure the horse’s success as a valuable means of transportation.
The study also unveiled that the horse spread throughout Asia alongside spoke-wheeled chariots and Indonesia-Iranian languages. On the other hand, migrations of Indo-Europeans during the third millennium couldn’t rely on these animals for transportation, as their domestication happened afterwards. This shows how important it is to combine the history of animals and the history of humans when studying migrations.