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Biting flies are actually the reason behind the evolution of zebra's signature black-and-white stripes, according to a new study.

The origin of the stripes was first debated 120 years ago when a team of scientists concluded that the stripes protected the creatures against flies. To reach the previous conclusion the team first mapped the regional distributions of seven different types of zebras, horses and asses along with their subspecies. They noted the solidity, intensity of their stripes for a number of areas on their bodies and locations. 

Ultimately, the team evaluated the striped animals where they found these factors being overlapped. In subsequent comparison they were able to rule out all possibilities except one which was protecting against the two biting flies.

"I was amazed by our results," said study author Tim Caro, a University of California-Davis professor of wildlife biology in the press release. "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."

Researchers also found that striping is strongly connected with several consecutive months of ideal conditions of horsefly breeding. They added that as zebra hair is shorter than the mouthpart length of biting flies, they are uniquely susceptible to biting flies and hence ended up in developing the unique coloration. 

"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."

Researchers were also interested in knowing what attracted the flies the most. They varied the patterns on several models which included solid black or white, or black and white striped squares, as well as black, brown, white, or striped life-sized plastic horses. They found that the stripes were the least attractive pattern to the horseflies more so than the solid white surface, according to RedOrbit. 

The study has been published in the journal Nature Communications.