A couple small mutations helped turn skittish animals into the creatures humans could saddle and ride:
Researchers led by Xuexue Liu and Ludovic Orlando analyzed horse genomes spanning thousands of years, tracking 266 genetic markers tied to traits like behavior, body size, and coat color. Their results, published in Science, suggest that early domestication didn’t begin with flashy coats or taller frames. Instead, the first breeders unsurprisingly selected for temperament.
One of the earliest signals of selection appeared at the ZFPM1 gene, linked in mice to anxiety and stress tolerance. That genetic shift, around 5,000 years ago, may have made horses just a little calmer — tame enough for people to keep close.
But the real game-changer came a few centuries later. Around 4,200 years ago, horses carrying a particular version of the GSDMC gene began to dominate. In humans, variants near this gene are associated with chronic back pain and spinal structure. But for horses and lab mice, the mutation reshapes vertebrae, improves motor coordination, and boosts limb strength. In short, it made horses rideable.
The numbers are staggering. The frequency of the GSDMC variant shot from 1% to nearly 100% in just a few centuries. Laurent Frantz of Ludwig-Maximilians-Universität München, who wrote an accompanying commentary, calls the selection “almost unprecedented in evolution.” For comparison, the human mutation that lets adults digest milk — a trait with huge survival advantages — spread far more slowly, with a selection strength of only 2–6%.
“The right conditions for the rise of the rideable horse materialized ~3,500 years ago in the Eurasian Steppe, north of the Caspian Sea,” Frantz explained. That’s when local cultures began seeking animals for war and transport rather than food. The genetic stars aligned: rare mutations already present in wild horses met human ambition.
“Between the time when the oceans drank Atlantis and the rise of the sons of Aryas, there was an age undreamed of.”
The proto-Indo-Europeans tamed the horse and invented the cart, then conquered most of the world.
Of course, Howard.
Another fantasy writer who got the history right was Auel in her “Cave of the Bear Clan.” She predicted Neanderthal/Sapiens hybrids before the were discovered.
Yeah, the old Robert E. Howard version is actually pretty much what happened.
The really interesting question is: what few centuries of selective pressure does to tame bi-pedals?
Say, for 3-5 centuries we conduct several local or not so local wars, add few Civil wars and/or revolutions (US, Russia, China), then append with 2 global wars in a span of half-century, culling men who are (for the lack of better definition) “the first out of trenches at the ‘attack’ signal”?
For example: <>
What traits got diminished?
Any research on it?