The question of why zebras have stripes has been a zoology mystery for as long as humans have known that zebras exist, or at least since the 1870s. Evolution proponents Charles Darwin and Alfred Russel Wallace had some famously different ideas about the evolutionary purpose of stripes on a zebra. They’re pretty unique in the animal world, with their bold black-and-white coloring and vibrant stripes. Recent research may have unlocked the mystery once and for all (though, then again, maybe not).
There have been five main theories touted by researchers: the stripes act as insect repellant, the stripes allow the herd to hide in plain sight, the stripes create visual confusion for predators, the stripes help zebras remain cool in the hot sun, or the stripes are part of the zebra’s social interaction. Tim Caro of the University of California Davis led a study to get to the bottom once and for all by collecting data on stripe patterns and prevalence across all zebra species and subspecies and comparing that data to the unique environment each species lived in, including any information about the environment that would support or debunk any of the main theories.
The results? The only consistent benefit of stripes was as insect repellant, and the more irritating insects were concentrated in one area, the more likely you are to find zebras and other striped species. Caro’s findings are supported by a recent study that found that horse flies can be confused and repelled by striped patterns, although the patterns used in that study weren’t the same as the patterns found on zebras.
Some detractors argue, and rightly so, that while Caro’s study was expansive and thorough, it lacked much of the nuances needed to provide a compelling, end-all answer to the perennial question. It seems that the answer won’t be so easy, and we’ll probably learn a lot more about zebras before we can pin down just how their stripes help them survive. It’s also likely that multiple theories can be true at one time.