Researchers analyzing ancient horse genomes have identified two key gene variants that likely played crucial roles in early horse domestication by making horses tamer and more physically suited to carrying riders. One gene, ZPFM1, associated with anxiety and well-being, underwent strong selection about 5,000 years ago, suggesting early efforts to reduce horse anxiety and increase tameness. Another gene near GSDMC, selected between 4,700 and 4,200 years ago, affects spine structure and limb strength, traits that would enhance a horse’s ability to bear weight and be ridden. Experiments with genetically modified mice supported these findings, showing that GSDMC influences skeletal traits linked to riding suitability.

These genetic changes coincided with a rapid increase in the frequency of the beneficial GSDMC variant, indicating intentional breeding by humans to enhance horse riding capabilities. The domestication of rideable horses was a transformative development in human history, enabling greater mobility and altering warfare and transportation. While these findings provide strong genetic evidence for traits targeted during domestication, researchers acknowledge that other important genes or cultural practices may also have contributed to the success of horse domestication and the rise of horse-powered societies across Eurasia.