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Zebras Are Striped to Deter Blood-Sucking Biting Flies, Scientists Conclude

| by Allison Geller

Where did zebras get their stripes? The question has puzzled scientists since Darwin. A new study claims to have cleared things up.

Researchers at UC Davis postulate in a new paper titled “The function of zebra stripes” published in Nature Communications that stripes evolved on zebras to deter biting flies. To test this hypothesis in the early stages, researchers used striped cardboard pieces dabbed with glue, according to lead author Tim Caro, a professor of wildlife biology.

Caro and his team mapped out geographic distribution tested Old World seven species against the hypothesis, including zebras, horses, and asses and their 20 subspecies.

“We observed that stripped species have a great degree of geographical range overlap with biting flies," Cato told the Christian Science Monitor.

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Biting flies like horseflies and tsetse flies are a common annoyance in the geographical areas where zebras are found, scientists found. The theory holds more water, they say, than those put forth by Darwin and others for the past 120 year, including camouflage, heat management, visual confusion to prevent against attacks by carnivores, and a social function.

The only one that stood up to tests, the scientists found, was avoiding blood-sucking flies.

"I was amazed by our results," Caro told EurekAlert! "Again and again, there was greater striping on areas of the body in those parts of the world where there was more annoyance from biting flies." 

"No one knew why zebras have such striking coloration," Caro said. "But solving evolutionary conundrums increases our knowledge of the natural world and may spark greater commitment to conserving it."

Sources: Newser, Christian Science Monitor, EurekAlert!