How Coat Color Preferences Changed Through Time

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.

- Christine Barakat and Mick McCluskey

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.