Around 6,000 years ago, humans began taming horses. Evidence shows that humans used horses for transport in the Eurasian Steppes near the Black Sea. This is significant because that region was one of the first civilizations to develop agriculture about 9,000 years ago.
The horse-human bond transformed agriculture. It proved to be a powerful addition to any army, whether the beasts were used solely for transport or as terrifying adjuncts to infantry. A civilization that mastered horsemanship dominated its world.
How did this power coupling come about?
Changes in human society and the horse's genes proved fortuitous. As humans learned to use the horse for more complex tasks, and horses were bred to perform those tasks more efficiently, a symbiotic relationship formed that eased the horse's transition to domestication.
Now, researchers from France, China, and Switzerland say that "they have identified the specific genes in horse lineages that may have made it possible for humans to start taming and mounting these muscular animals," according to Nautilus.
By tracing genetic changes in the horse, the researchers have determined that these domestication genes began to appear about 5,000 years ago. According to Nautilus, the genes "are involved in temperament, movement, and the way horse bodies are shaped."
“These genetic changes allowed horses to become rideable and fast-moving, which transformed human societies by accelerating transport, warfare, and cultural exchange,” says lead author Xuexue Liu, a postdoctoral researcher. He is affiliated with the Centre for Anthropobiology and Genomics of Toulouse in France.
“In short, horse genetics and human social development co-evolved in a mutually reinforcing process.”
We find this in many "working animals" domesticated not only for food, but to perform specific tasks.
Liu and colleagues analyzed ancient horse DNA collected from archaeological sites, tracking how 266 trait-associated genetic markers changed over the period when humans were breeding them. One pair of genes known as GSDMC and ZFPM1 also appear in other animals, such as mice, which helped researchers isolate and observe the effects of the genes. GSDMC is linked to spinal anatomy, motor coordination, and strength in mice, they found, while ZFPM1 is associated with anxiety and learning.
“I think this study shows very clearly that horse domestication was paired with, and probably motivated by, a desire for horse transport,” William Taylor, an archaeozoologist at the University of Colorado Boulder, wrote in an email. “The first horse herders were raising horses with only a few things in mind, namely their behavior—friendliness, aggression—and their movement/roles in transport.”
Riding came later.
“These finds suggest that early horse transport—relying heavily on chariot teams—was probably much different than the kind of mounted riding we know today, with different values and different logistics,” said Taylor.
Taylor also pointed out that the findings of the study suggest that humans had little relationship with horses before 3,000 B.C. and that in those early years, humans used them almost exclusively for transport. “That’s exciting, and points us toward a very different understanding of horse domestication than has been the status quo.”
In a related Perspective, also in Science, Laurent Frantz, who studies zooarchaeology and evolutionary genomics at Oxford University, pointed out the impressive significance to history of the very first horseback riders—and these tiny bits of DNA the researchers identified.
“Although the precise circumstances and the cultural identity of the people responsible for this early, intensive breeding remain a mystery, they must have had the necessary ingenuity, technology, and foresight,” writes Frantz. “What is certain is that these first riders kick-started a revolution that changed the world, demonstrating how the immense currents of history can turn on the smallest of biological changes.”
It's fascinating how certain societies bred horses for specific tasks. Northern Europeans bred extra-large horses to pull the heavy plows through rocky soil. Ghengis Khan's Mongols bred small, extremely swift horses with incredible endurance, trained to be fearless in battle and loyal to their rider to death.
The ability of horses to be bred for specific tasks reinforced the human-horse bond, leading to a snowballing domestication process. Imagining those first efforts to ride a 1,000-pound animal with no saddle or bridle puts me in awe of those early horsemen and their initial efforts to tame wild horses.
