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Finally, Science Has A Plausible Reason For Zebra Stripes
April 2, 2014
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(Photo: ROBERTO SCHMIDT/AFP/Getty Images)

Why do zebras have stripes? It's a question we've been asking for centuries, but it always seemed like a rhetorical one — you know, just another mystery of the great animal kingdom, an ever-present fact of life in the savannah, cue the Lion King music and get over it. Even Darwin couldn't figure out the reason for zebra stripes, variously ascribing them to camouflage, mating rituals and just plain beauty. 

But this week, the riddle might well have been answered.

According to a new study published in the journal Nature Communications, scientists from the University of California, Davis believe that zebra stripes evolved to keep flies away. 

So, there you have it. Mystery solved. 

“We found again and again and again [that] the only factor which is highly associated with striping is to ban biting flies,” said study leader Tim Caro, a biologist at UC Davis. “I was delighted to see the results were so strong in one direction.”

This idea — that flies are repelled by stripes — originated in the 1930s. Caro and his team studied previous attempts to link flies to stripes, as well as looking at striping patterns on the seven species of equide (that's science for horses) that have stripes on their bodies. They cross-referenced the patterns with where those animals lived, and found a tight correlation with areas where biting flies are prevalent. For example: anywhere scientists located tseste flies, scientists also located equids with stripes. No tsetse flies, no stripes. 

However, it's still not known exactly why the biting flies would avoid stripes. Scientists acknowledge that there's still much more research to be done to prove this theory. For one thing, they haven't observed the zebras in the field to see their interaction with flies firsthand, mostly because it's expensive and difficult to get close enough. There are also other hypotheses — that stripes allow animals to recognize each other, for example, or that they have a hand in keeping the animals cool in the African heat — that need to be better tested.

Still, it's a step closer to answering an age-old question.

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


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