170428 horsetomb thumb

An ancient horse tomb in Siberia

The domestication of the horse, believed to have first been accomplished by the Botai people of the Kazakh steppe around 3500 BC, changed human civilization dramatically. Horses made it possible to move much more quickly, connected previously far-flung places, and revolutionized war. Horse power was instrumental even to city life until the rise of the internal combustion engine in the early 20th century.

As horses changed us, so did we change them. A new analysis of the genomes of 16 ancient horses, found in tombs like the one shown above, has revealed the transformation brought about by the selective pressures imposed by human breeders.

The study, published in Science, found that the early Scythian breeders avoided inbreeding among their horses, while selecting for greater milk production and stronger forelimbs.