A recent study analyzing ancient horse genomes reveals how selective breeding shaped horses into calm, rideable animals capable of carrying humans over long distances. Early breeders prioritized temperament, favoring calm and trainable horses before focusing on physical traits like body size, strength, and coordination necessary for speed, weight-bearing, and endurance. A key genetic region, GSDMC, linked to spinal structure and muscular strength, emerged around 4,750 years ago and became prevalent by 4,150 years ago, marking a critical shift toward rideability during the domestication bottleneck.

The research also identified the gene ZFPM1, associated with behavior, as undergoing positive selection about 5,000 years ago, indicating that tameness was the first trait targeted by humans. From the Iron Age onward, breeding emphasized larger, stronger horses suited for transport and warfare, reflecting archaeological evidence of cavalry use. This genetic timeline not only clarifies how horses transformed human mobility and culture but also highlights the ongoing importance of balancing performance with animal welfare in modern breeding practices.