How coat color preferences changed through time

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Colorful Appaloosas and flashy Paints enjoy a loyal following today, but new research suggests that over the millennia spotted horses have gained and fallen out of favor depending on larger currents in society.

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Researchers from academic institutions across Europe teamed up under the guidance of the Leibniz Institute for Zoo and Wildlife Research in Berlin, Germany, to collect and test DNA from 201 ancient equine samples to determine the coat color phenotype of each horse. 

“Any tissue which contains DNA can be used for coat-color genotyping,” says Arne Ludwig, PhD. “We prefer teeth and femurs because DNA preservation is very good in them. Petrosal bones [found in the skull] are also known for their excellent DNA preservation.” The earliest samples in the study dated back to the Pleistocene era, before 4000 b.c., when horses were first domesticated. The most recent samples were from the Medieval Age, which ran from around the fifth to the 15th centuries.

Within the earliest samples the researchers identified six color variants, half of which were also found in horses before the species was domesticated. In the later samples, the color variants increased to nine, indicating that humans had begun selectively breeding horses based on color preferences. During the Iron Age (900 b.c. to a.d. 400), the phenotype for spotted horses---specifically leopard, tobiano and sabino---were found nearly as often as that for solid colors. 

“We don’t know why they preferred spotted horses during the Iron Age,” says Ludwig. “Probably because they looked different from wild horses. They were something special, and humans at any time prefer special things.”

All that changed, however, in the Middle Ages. Samples from that period show a dramatic decline in the number of spotted horses. This drop could be due to a number of factors, says Ludwig. 

For starters, the fall of the Roman Empire likely disrupted the organized breeding efforts that were producing so many spotted horses. “Romans had a very efficient organization of animal breeding,” he says. “For example, they transported bulls from Italy to many regions of their empire and used only them for producing offspring. Therefore, nearly all modern taurine cattle breeds have their genetic roots in Southern Europe. This organization was lost with the fall of the Roman Empire. Animal breeding was scattered throughout Europe and became more diverse.”

Spotted horses also could have become less popular because of cultural and religious shifts. The researchers note that the Four Horsemen of the Apocalypse, as described in the Book of Revelation, initially indicated the rider mounted on the white or white-spotted horse symbolized victory, while riders of the darker horses heralded famine, death and war. In the Medieval period, however, a series of epidemics such as the Black Death ravaged Europe, and the rider of victory was replaced with the rider of pestilence, still mounted on the white horse. This, the researchers say, may account for the sudden decrease in popularity of horses with large amounts of white, including spotted horses.

The advent of modern weaponry, such as the longbow, may have also influenced a change in color preferences, according to the research team. A light-colored or spotted horse would have been an easier target at a distance. 

While the exact cause of the decline in spotted-horse popularity during the Middle Ages may be lost to history, Ludwig says modern trends cannot be disputed, even by future generations: “I cannot look into the future, but I would say, considering technology, they won’t need genetics [to know spotted horses are popular today]. They will have photos, videos and movies to go by.” 

This article was originally published the April 2016 issue, Volume #475 of EQUUS magazine

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