The Origin of Modern Horses Resolved

10:05, November 8, 2021

They appeared in the Volga-Don region of Russia, scientists found out

An international team including Russian researchers has solved the mystery of the origin of modern horses. Deciphering the hereditary material of 273 ancient horses from across Eurasia put an end to the contradictory conclusions of predecessors and years of controversy. The study proved that the horse in its modern form first appeared about 2,200 years B.C. in the Volga-Don region of Russia and then "conquered" Asia and Europe within a few centuries. Just a couple of genes, which conditioned its strong skeleton and obedience, ensured its popularity among elite equestrians of the Bronze Age. The results of the work, supported among other things by grants from the Russian Science Foundation (RSF), were published in the journal Nature.

"Work on the history of horse domestication based on the results of paleo-DNA analysis began several years ago. A number of articles have published the private results of these studies. This article is the result of these many years of research," explains Pavel Kosintsev, co-author of the article, a senior researcher at the Institute of Plant and Animal Ecology of the Ural Branch of the Russian Academy of Sciences and a leading researcher at the Laboratory of Natural Science Methods in Humanities Research at UrFU.

The characteristics of the material to be included in the analysis are important in the study. If samples are examined that have little or erroneous information about them, the interpretation of DNA analysis results will be difficult or even incorrect.

"I have been studying horse bones of the Ural-Volga region and Western Siberia for 40 years using traditional methods - morphological and morphometric. Archaeological data are also taken into account. According to these researches we defined domestic or wild horses from many archaeological monuments. That's why when we started the DNA research we formed samples for them in such a way that we included bones of domestic and wild horses. This further facilitated the analysis of the results," says Pavel Kosintsev.

The domestication of horses radically changed the life of ancient man: with the help of this strong and fast animal, he was able to move more efficiently, keep the economy and conquer new lands - remote for hundreds of kilometers and occupied by competitors. Yet even this historical importance and long years of research have not unequivocally answered the questions: when and where did modern horses emerge and why did they supplant the other breeds that inevitably came across their path?

"Three years ago, my team examined the remains of the oldest domesticated horses in existence, which were about 5.5 thousand years old. The DNA results were disappointing: these creatures did not turn out to be the ancestors of the modern horses we were trying to locate. We needed to look further, we knew that the clue lies somewhere between 4000 and 6000 years ago," says CNRS research professor Ludovic Orlando.

In the new work, a team of 162 scientists from around the world, including Russia, finally put a dent in the search for the origins of modern horses. They deciphered the genomes of 273 animals that lived in Eurasia between 50,000 and 200 B.C., and compared them with the DNA of modern ungulates. This is what helped achieve the goal of many years of research.

The results showed that various horse breeds inhabited Eurasia, but that between about 2000 and 2200 BC, a sort of revolution took place. In the Ponto-Caspian steppe stretching from the Black Sea to the Urals (most likely in the Volga-Don region of modern Russia), a type of domestic horse appeared, which gradually spread across Eurasia, displacing other forms. Only one pair of genes was sufficient for success, providing the animals with a strong back and obedience.

"Interestingly, the popularity of these horses, which gave rise to the modern species, was largely due not to cattle breeding, but specifically to horseback riding - travel and sport for the entertainment of the Bronze Age elite. As a result, they became a valuable commodity, a symbol of wealth and status, and so they began to be actively bred. A comparison of our results with the archaeological findings suggests this. In addition, the use of horses contributed to the spread of information and technology. The mystery of the origin of modern horses seems to be solved, but it entails the necessity of rethinking the processes of human settlement and the spread of cultures in Eurasia," notes project leader Vladimir Pitulko, a senior research associate of the Institute for the History of Material Culture of the Russian Academy of Sciences (St. Petersburg).

The results of the study are of great importance for further understanding of the mechanisms of biological evolution, which resulted in, among other things, the emergence of domesticated forms of wild animals useful to humans.