Why do zebras have stripes? For a long time, researchers assumed they were to confuse predators while zebras stood in herds. But increasingly, scientists are reaching a different conclusion: Stripes protect zebras from biting insects. A new study helps explain exactly how.
To reach this conclusion, a group of scientists tested their theory on a group of horses and zebras wearing different kinds of coats. The researchers dressed both horses and zebras in black coats, white coats, and striped zebra coats. The idea was to test how flies reacted to each type of coat, and the researchers used both horses and zebras to make sure it really was the coat that was making the difference.
From a distance, flies seemed to be equally attracted to both horses and zebras regardless of what kind of costume each was wearing. But when flies got close to a striped coat—real or synthetic—they got confused, bumping into the coat or just flying off in a random direction. The end result is a lot fewer bites for the zebra or the coat-wearing horse.
So why do striped zebras confuse flies so much? The scientists aren’t completely sure, but they have a few guesses. It’s possible that the stripes act as a kind of optical illusion, messing with the flies’ navigation and disorienting them. Another possibility is that the stripes prevent the flies from seeing the animal as a solid object, so the flies don’t realize they’re about to hit something until it’s too late.
In the African savannah biting flies are common, and many carry deadly diseases. Finding a way to prevent these flies from biting has a very strong evolutionary advantage for zebras. And now that we know what striped patterns actually do, maybe we can use them to give our horses the same advantage.
Originally posted on Popular Mechanics