Researchers Discover Crucial Genetic Changes That Facilitate Horse Domestication for Riding
Image: Helena Lopes via Unsplash
In the realm of wildlife, only a few species can be depended on for transportation, including elephants, camels, mules, and llamas. However, horses stand out as perhaps the most prevalent. For thousands of years, humans have mounted these graceful, powerful animals, which fundamentally changed the dynamics of travel, combat, farming, trade, and civilization. Experts have long been intrigued by the factors that made horses suitable for domestication—and fresh research might provide insights.
Recently featured in Science, the research presents two key gene mutations that enabled us to domesticate and eventually ride untamed horses. These mutations surfaced approximately 5,000 years ago, influencing traits such as temperament, mobility, and general biology. To pinpoint these specific genes, researchers examined the genomes from 71 horses across different breeds and eras, including ancient horse DNA retrieved from archeological sites. The team then traced the evolution of 266 genetic markers during the early domestication phase, identifying nine genes selected by human breeders. Among these genes, two stood out: ZFPM1 and GSDMC.
In mice, ZFPM1 affects anxiety levels, and in humans, it impacts overall health. Conversely, GSDMC is associated with spinal structure, motor skills, and muscular strength in mice, and chronic back issues and pain in humans. The study indicates ZFPM1 underwent significant selection around 5,000 years ago, hinting that this gene was vital for early horse domestication, while GSDMC faced strong selection from 4,200 to 4,700 years ago.
Combining these findings, the research team suggests that ZFPM1 contributed to a horse’s gentleness, making it easier to train. GSDMC had physical implications, modifying the animal’s body shape and structure, including its spine. To further investigate this hypothesis, scientists deactivated the GSDMC gene in laboratory mice, which resulted in straighter spines and more robust forelimbs. These characteristics, according to the research, enhance rideability by improving posture, weight distribution, and mobility. Notably, the GSDMC gene surged in prevalence within just a few centuries, rapidly disseminating across horse populations.
“That indicates that people were aiming to increase that variant’s presence in the population,” Ludovic Orlando, one of the authors of the study, mentioned to Science News, stating that horses with the GSDMC mutation had approximately 20% more offspring than those lacking it. “When trends like that appear, it’s clear you’re onto something that fundamentally changed horse biology.”
In 2021, Orlando and his team discovered evidence that contemporary domesticated horses trace back to southwestern Russia over 4,200 years ago. This latest study, however, provides a new perspective on how horses were domesticated by ancient societies through a genetic framework.
“These genetic modifications enabled horses to become rideable and quick, drastically altering human societies by enhancing transport, warfare, and cultural interactions,” lead author Xuexue Liu noted in a discussion with Nautilus. “In summary, horse genetics and human societal evolution developed in a mutually supportive manner.”
To discover more about these intriguing findings, explore the complete study in Science.