The genetic trick that helped humans ride a horse

About 4,500 years ago, humans forged a link that would shape the history of our species. Horse domestication has led to significant progress in transport, hunting and war, literally transporting human society in the modern era.

Despite the way horses have been influential for humans, scientists still have many fundamental questions about their domestication. New research published on Thursday, August 28 in the journal Science, offer new previews on the genetic changes that have helped them to become tamed and ripable. The results claims not only the story of a critical human-animal link, but could also help today guide the efforts to reproduce horses and conservation of conservation efforts.

“By traveling in time, you (can see) the impact of these reproductive practices on the modern world,” the co-author Ludovic Orlando, research director of the National Center for Scientific Research and head of the Center of Anthropobiology and Genomics of Toulouse, told Gizmodo Orlando.

Indices hiding in old DNA

The Orlando laboratory has spent the last 15 years meticulously sequenced the genomes of ancient horses dating nearly a million years ago until the 19th century. For this study, he and his colleagues analyzed hundreds of genomes from the 6,000 -year domestication period. They identified 266 genetic markers linked to key features such as behavior, color of the mantle, body shape, locomotion, athletics and sensitivity to diseases to see how selective reproduction has influenced them over time.

The researchers discovered that around 5,000 years ago, during the early stages of horses’ domestication, selective farming has favored a genetic region (or locus) associated with the ZDPM1 gene. This gene is a modulator of known behavior in mice, suggesting that taming was one of the first stages towards domestication of horses.

About 250 years later, humans began to intensely select Locus GSDMC, a DNA region linked to bodily confirmation in horses and vertebral anatomy, coordination and force in mice. The moment of this aligns with the “bottleneck bottle of domestication”, when increasingly selective breeding has resulted in a strong reduction in genetic diversity.

“The selection was not only very strong, but the timing was down,” said Orlando.

Rewrite the history of the domestic horse

To further validate the function of Locus GSDMC, the co-author Lin Jiang, professor at the Chinese Academy of Agricultural Sciences and longtime collaborator of Orlando, has changed this DNA region at the mouse. She and her colleagues then used CT scans to search for physiological changes and carried out strength and coordination tests.

The modified mice have proved to be much stronger and displayed an improved locomotion, reflecting changes in the horse phenotype which supported the driving or transport of heavier loads on the back, Jiang told Gizmodo.

Demonstrate these biological effects and link them to the point during selective farming which immediately preceded the globalization of domesticated horses was “breathtaking,” said Orlando. In addition, the results contradict a long -term hypothesis that humans have started to domesticate horses by selecting a diversified coloring, which facilitates their distinction.

“What was really surprising for me in our data is that we do not see the evidence of color being the trigger at the very beginning,” said Orlando.

Receiving the genetic changes that have shaped equine domestication also help scientists understand their consequences for horses today. “We have realized that around 16% of the genetic diversity of horses has been lost in the past 200 years, simply because of the way we have raised these animals since the 19th century,” said Orlando. Analysis of ancient DNA, he added, can tell scientists a lot about history but can also guide modern reproduction practices.