Why do zebras have stripes?

Zebra painting stripes on himself. Illustration by John Megahan.

The mystery behind zebra’s striped pattern may be solved. Alumnus Amanda Izzo (Ph.D. EEB 2011) and researchers at the University of California Davis, published a study in Nature Communications explaining their “black and white” findings.

According to a blog post in Discover, “Researchers going as far back as Charles Darwin have offered a number of theories about how stripes might benefit zebras. Did they develop their unusual multi-hued coats as camouflage to help deter predators? To keep cool beneath the harsh African sun? Do their stripes help them identify each other? A new study topples all of those theories, leaving just one still standing. As it turns out, stripes are an excellent bug repellent — at least for zebras.

“Researchers from UC Davis knew that certain flies avoid black and white surfaces, so they wondered: Could zebra stripes have evolved to keep the animals free from suffering the bites of those very same flies, which can carry fatal diseases? To tackle that question, the researchers examined the distribution of zebras and the locations of the best breeding grounds for the stripe-averse flies. Sure enough, they found that they overlap. The same was true for other animals in the horse family that had stripes on various parts of their bodies.”

“I was amazed by our results,” said lead author Tim Caro, a wildlife biologist at UC-Davis. “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.”

Izzo is a postdoctoral researcher in the Department of Wildlife, Fish and Conservation Biology, UC Davis.

The paper received widespread media attention. Read the paper in Nature Communications and more in Discover and National Geographic.

Illustration by John Megahan.