New DNA analysis has pinpointed what changed in ancient horses to the domesticated ones today that run in races.

According to the Chicago Tribune, authors of a study published in the journal Proceedings of the National Academy of Sciences found widespread horse domestication in Eurasia about 5,500 years ago. This obviously had a profound effect on the world for travel, trading and virtually all aspects of society.

"The classical way to evaluate the evolutionary impact of domestication consists of comparing the genetic information present amongst wild animals and their living domesticates," study lead researcher Dr. Ludovic Orlando, associate professor at the Centre for GeoGenetics, said in a press release. "This approach is ill suited to horses as the only surviving population of wild horses has experienced a massive demographic decline in the 20th century. We therefore decided to sequence the genome of ancient horses that lived prior to domestication to directly assess how pre-domesticated horses looked like genetically.

"Perhaps even more exciting as it represents the hallmark of animal domestication, we identify genes controlling animal behavior and the response to fear. These genes could have been the key for turning wild animals into more docile domesticated forms."

For their study the researchers examined the fossil of a horse believed to be about 700,000 years old. They also sequenced the genomes of horse specimens approximately 16,000 and 43,000 years old, respectively.

"This confirms previous findings that wild horses were used to restock the population of domesticated horses during the domestication process," study co-lead author Mikkel Schubert, a PhD- student at the Centre for GeoGenetics, said in the release. "However, as we sequenced whole genomes, we can estimate how much of the modern horse genome has been contributed through this process. Our estimate suggests that at least 13%, and potentially up to as much as 60%, of the modern horse genome has been acquired by restocking from the extinct wild population.

"That we identified the population that contributed to this process demonstrates that it is possible to identify the ancestral genetic sources that ultimately gave rise to our domesticated horses."