zoo-logic:

For a long time, the history of the domestication of the horse has been a muddled one. While archaeological evidence suggests that the domestic horse (Equus caballus) originated in the western Eurasian steppes (Ukraine, southwest Russia and west Kazakhstan), a large variety of female lineages in the gene pool contradicts this, implying not a single origin but instead multiple domestication events. An important unanswered question was whether the spread of horse domestication around the world involved the actual movement of herds from a specific geographic origin, known as ‘demic spread’, or whether it simply involved passing on successful techniques so that people in other regions could domesticate their own local wild horses, resulting in multiple domestication events from numerous different populations. New research that has analysed mitochondrial DNA and Y-chromosomes from a genetic database of over 300 horses has finally resolved the answers to these questions. The data has traced the origins of domestic horses to a single ancestral population of Equus ferus (now extinct) that was indeed living in the western Eurasian steppes from at least 160,000 years ago. Humans first domesticated the horse in this region around 4000 B.C., and from here domesticated horses spread outwards across Europe and Asia, in the process of which stock was supplemented with local wild horses in different regions. These wild horses that were bred into domestic herds were the source of the new female lineages that we can identify in the gene pool today.

Ref: Warmuth V., Eriksson A., Bower M. A., Barker G., Barrett E. et al., 2012. Reconstructing the origin and spread of horse domestication in the Eurasian steppe. PNAS Online [link]