Scientists from the National Academy of Sciences have annoucned that they have mapped the genome of the horse and learned much about the history of horse domestication.

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

Obviously this is a huge step to understanding human histroy, as the introdcution of the horse revolutionized trade and travel. Something many scientists suspect is part of the very begining of civilizations itself. At the very least larger groups of people could never have organized without communication through horseback.

It was all made possible by 125 genes related to skeletal muscles, balance, coordination, and cardiac strength. These traits were specifically bred to make different breads of horses for chariots, plowing, and racing. Genes active in the brain also underwent selection, especially areas linked to social behavior, learning, fear response, and agreeableness are all more abundant in domesticated horses.

This process of discoving the genetic differences between domesticated and wild horses had some previous difficulties, as no living truly wild horses still exist.The closest alive is the Przewalski's horse. There remain some wild horse populations in various places. Europe and North America boast isolated instances of this, but it has long been known that these are rag-tag groups of escaped or released domestics that have returned to the wild - not true wild populations.

"Comparing ancient genomes to modern genomes is tricky," said Arne Ludwig of the Leibniz Institute for Zoo and Wildlife Research in Berlin.

Instead of living horses the team examined DNA from 29 horse bones discovered in the Siberian permafrost and dating from 16,000 and 43,000 years ago, and compared it to DNA from five modern domesticated breeds.

Geneticists not involved in the study suggested that analyzing equine DNA from around the time of domestication, rather than millennia before, might show more clearly what genetic changes occurred as horses were tamed.

The studyrecently published in the journal Proceeding of the National Academy of Sciences (PNAS) details how experts were able to sequence the genetics of these wild horses and a few of their domestic counterparts. By doing so, the team was able to identify a set of 125 specific genes that likely led to the near domestication of horses.

Some genes in today's horses were absent altogether from the ancient ones, showing they arose from recent mutations. Among them: a short-distance "speed gene" that propels every Kentucky Derby winner.

"We provide the most extensive list of gene candidates that have been favored by humans following the domestication of horses," researcher Beth Shapiro explained in a statement. "This list is fascinating as it includes a number of genes involved in the development of muscle and bones. This probably reveals the genes that helped utilizing horses for transportation." 

However, this domestication came at a cost. As is seen in dog populations, the extensive domestication of these animals led to a loss in healthy genetic variety, and the inevitable accumulation of invisible "bad genes."

"Mutations that negatively impact genes are not eliminated by selection and can even increase in frequency when populations are small," explained Laurent Excoffie, the group leader at the Swiss Institute for Bioinformatics. "Domestication thus generally comes at a cost, as deleterious mutations can accumulate in the genome. Horses now provide another example of this phenomenon."