Descendants of the world's last known wild horses are remarkably different from domesticated horses, with a new genetic study showing that the two groups went their separate evolutionary ways 45,000 years ago.
The existent horses with true wild ancestry, Przewalski's (pronounced shuh-VAL-skee's) horses, even have a different number of chromosomes, according to the study that is published in Current Biology. The research found that genes involved in metabolism, cardiac disorders, muscle contraction, reproduction, behavior and signaling pathways differ between
and domesticated horses.
All of these differences would tend to support that Przewalski's horses represent an entirely unique species, but because these mammals can produce fertile offspring after mating with domesticated horses, they are considered as a different population, but not as a different species.
Animal experts have debated the issue for years.
"The debate comes from the fact that first, Przewalski's horses do not look like domestic horses," senior author Ludovic Orlando of the University of Copenhagen's Natural History Museum of Denmark told Discovery News.
He continued, "They have a dun coat color (no fancy colors, for instance), they are quite stockily built, their face looks more robust, and they are rather aggressive. They have never been successfully domesticated, perhaps in relation with their strong temper."
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