COPENHAGEN, Denmark, Dec. 16 (UPI) -- Geneticists in Denmark have isolated the genetic effects of humans' domestication of the horse. Over some 5,500 years, humans selectively bred a variety of horse species, harnessing and repurposing their wild power for a litany of labor-intensive tasks and a diverse range of environments.
During (and as a result of) this process, horses had a tremendous effect on human culture -- helping modern man rapidly circulate ideas, languages and religions, as well as revolutionizing trade and warfare. But the process also had a tremendous effect on horses themselves, diminishing the diversity of its genome and pushing the animal's wild ancestors to the brink of distinction.
The latest study on the subject -- one of the most comprehensive analyses of the horse genome yet -- not only identifies the horse genes favored by humans during the domestication process, but also the associated genetic and ecological costs.
The study, carried out by scientists at the University of Copenhagen's Center for GeoGenetics, detailed some 125 genes related to physical and behavioral traits favored by humans. By comparing the genomes of modern domesticated horse varieties to DNA sampled from now-extinct wild horse species, researchers were able to isolate genes that control skeletal muscles, balance, coordination, cardiac strength, fear response, and more.
The replication of these advantageous genes came at a price, however.
"The reshaping of the horse genome during their domestication also had significant negative impacts," researchers explained a recent press release. "This was apparent in the increasing levels of inbreeding found amongst domesticates, but also through an enhanced accumulation of deleterious mutations in their genomes relative to the ancient wild horses."
The research also proved that domesticators routinely reintroduced wild horse genes into domestic lineages as way to guard against the negative consequences of domestication. That technique isn't possible today, as only one species of wild horse remains -- Przewalski's horses, a wild Mongolian species saved only by a massive conservation effort.
The new study is published in the latest issue of the journal Proceedings of the National Academy of Sciences.