Researchers have traced the genetic steps that made horses suitable for riding, publishing their findings on 28 August in the journal Science. A team led by Ludovic Orlando at France’s Centre for Anthropobiology and Genomics of Toulouse, working with colleagues at the Chinese Academy of Agricultural Sciences, sequenced hundreds of ancient horse genomes spanning roughly 6,000 years of domestication history and examined 266 genomic regions under selection. The study identifies two pivotal loci. Around 5,000 years ago breeders favoured a variant near the gene known as ZDPM1 (reported in a parallel analysis as ZPFM1), which influences behaviour in other mammals and is thought to have reduced anxiety, making early horses easier to tame. Within the next three centuries, selection intensified for mutations at GSDMC, a gene tied to spinal structure and coordination; its frequency rose from near-absence to near-fixation between 4,700 and 4,200 years ago, providing stronger backs and improved locomotion for bearing riders. The work challenges the long-held idea that coat colour drove initial domestication, instead highlighting deliberate selection for temperament and physical robustness. The authors add that modern breeding has since erased about 16 percent of equine genetic diversity, underscoring the need to balance performance traits with conservation.