In the animal kingdom, there are only a handful of species that we can rely upon for transportation, ranging from elephants and camels to mules and llamas. But horses are arguably the most ubiquitous. For millennia, humans have ridden atop these sleek, muscular creatures, whose presence radically transformed travel, warfare, agriculture, commerce, and culture. Scientists have long puzzled over what specifically primed horses for domestication—and new research may just hold the answer.
Recently published in Science, the study outlines two crucial gene mutations that allowed us to tame and ultimately ride wild horses. These mutations first emerged some 5,000 years ago, and targeted such attributes as temperament, movement, and overall physiology. To identify these particular genes, the scientists analyzed the genomes from 71 horses of varying breeds and time periods, including ancient horse DNA extracted from archaeological sites. The team then tracked how 266 genetic markers evolved throughout the early domestication period, determining nine genes that were favored by human breeders. From this sampling, two genes made a strong impression: ZFPM1 and GSDMC.
In mice, ZFPM1 impacts anxiety levels, while in humans, it influences overall wellbeing. GSDMC, on the other hand, is linked to spinal anatomy, motor coordination, and strength in mice, and chronic back conditions and pain in humans. According to the study, ZFPM1 underwent strong selection about 5,000 years ago, suggesting the gene played a critical role in early horse domestication, whereas GSDMC experienced strong selection anywhere from 4,200 to 4,700 years ago.
Taken together, the team believes that ZFPM1 influenced a horse’s docility, rendering it easier to tame. GSDMC bore physical significance, altering the animal’s body shape and build, alongside the structure of its spine. To further test that theory, scientists silenced the GSDMC gene in lab mice, who developed straighter spines and stronger forelimbs. Such traits, per the study, betters the chances of rideability, improving posture, weight-bearing, and mobility. Notably, the GSDMC gene exploded in frequency over just a few hundred years, spreading rapidly throughout horse populations.
“That means people intended to put that variant more frequently in the population,” Ludovic Orlando, one of the study’s authors, told Science News, adding that horses with the GSDMC mutation had an estimated 20% more offspring than those without. “When you see something like that, you know you’re onto something that was really a game changer for horse biology.”
In 2021, Orlando and his team also found evidence that modern domesticated horses originated from southwestern Russia more than 4,200 years ago. This new study, however, offers a novel glimpse into how horses were domesticated by early civilizations, all through the lens of genetics.
“These genetic changes allowed horses to become rideable and fast-moving, which transformed human societies by accelerating transport, warfare, and cultural exchange,” lead author Xuexue Liu added in an interview with Nautilus. “In short, horse genetics and human social development co-evolved in a mutually reinforcing process.”
To learn more about these exciting results, read the full study in Science.
Scientists have identified two genetic mutations that were crucial in the domestication of horses.
These genes impacted temperament, movement, and overall physiology, all of which ultimately allowed horses to be mounted and ridden by humans.
Sources: Horses may have become rideable with the help of a genetic mutation; What Made Horses Rideable; Genetic Mutations Made Horses Gentle — and Changed Human History; Did a single genetic mutation make horses rideable?; Selection at the GSDMC locus in horses and its implications for human mobility
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