![]() ![]() They’re also very vulnerable to insect attacks: Compared with other grazers such as antelopes, the hairs on their coat are unusually short, allowing flies to more easily find blood vessels with their piercing mouthparts. For one, they’re highly susceptible to a variety of fatal diseases, including trypanosomiasis, African horse sickness, and equine influenza, that are spread by horseflies and tsetse flies. When it comes to biting insects, zebras are doubly cursed. But a recent study showed that water drums cloaked in zebra pelts heat up just as much as those covered in normal horse skins. Another hypothesis says that the black stripes heat up faster than the white ones, setting up circulating air currents that cool the zebras. But that can’t be true: Amanda Melin of the University of Calgary recently showed that lions and hyenas can’t even make out the stripes unless they get very close. Some researchers have suggested that the stripes act as camouflage-they break up zebras’ outlines or resemble fields of tree trunks. But, one by one, the most commonly proposed explanations have all been refuted. Scientists have been puzzling over the role of zebra stripes for more than 150 years. ![]() By comparing these two species, as well as horses that were comically cloaked in zebra-striped coats, the team found fresh evidence for what Caro thinks is the only plausible explanation for the striking stripes: They evolved to deter bloodsucking flies. In his latest bid to get clear answers, he and his colleagues traveled to Hill Livery, a stable in southwest England that keeps several captive zebras alongside domestic horses. “There are enormous benefits to having a striped coat for a horse,” he told me.Ĭaro, a biologist at the University of California at Davis, has spent years thinking about why zebras are striped, and has even written a book about this mystery. But, as Caro learned, such coverings have an unexpectedly serious effect. Several vendors were already selling coats with black-and-white stripes, often as fun gimmicks. For Tim Caro, it was surprisingly easy to dress horses like zebras. ![]()
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