Zebras: Why Do They Have Stripes? — Answer: It Isn’t Camouflage

The answer to the age-old question, “why do zebras have stripes?” has been answered by scientists.

Researchers have come up with many possible reasons in the past as to why zebras have stripes, including camouflage to help them elude predators, to avoid bites from disease-carrying insects, and to control body heat by “generating small-scale breezes” over their bodes when light and dark stripes heat up at a different rate.

However, researchers at the University of California at Los Angeles recently examined how 29 different environmental variables affect stripe styles of plains zebras in an area stretching from south to central Africa. By doing so, the scientists found that there was almost a direct correlation between the stripes on a zebra’s back and temperature and precipitation in a zebra’s environment. Conversely, the stripes did not correlate to the prevalence of lions or tsetse flies in their particular region.

As a result of the research, scientists have concluded that torso stripes on zebras may do more to help zebras regulate their body temperature than to avoid predators or disease-carrying flies.

Zebras especially need a body temperature regulation technique (called thermoregulation), as they digest their food less efficiently than other animals and as such must spend more time out in the heat of the African sun than other grazers, eating more food. The study of the zebras in Africa found that plains zebras with more defined torso stripes generally lived in the Northern, equatorial region of their range in Africa, while those with less defined torso strips were more common in the Southern, cooler regions. This finding supports the thermoregulation explanation for the zebra stripes.

Brenda Larison — a co-author of the study published in Royal Society Open Science — says that the relationship between color and heating is complex. Ravens, for example, hold their black feathers away from their skin to create a breeze. Larison says she and her colleagues already have preliminary data that the zebra’s black-and-white bands keep its external temperature lower than that of other animals of a similar size, suggesting that zebra stripes work remarkably well.

Tim Caro, a biologist at the University of California, Davis, says that this latest research debunks some other theories about zebra stripes.

“A lot of people in the public think that stripes have to do with confusing predators. This is the kiss of death for that particular idea.”

Researchers will now test their thermoregulation hypothesis. They’ll reportedly do so by either studying the behavior of air currents over zebra pelts, or by implanting wild zebras with temperature sensors.

[Image via Wired]