Why did zebras evolve to have stripes? Is it for camouflage or to deter biting insects? A new study finds that the creatures may be using their stripes to help regulate the heat.

Zebra Stripes For Camouflage?

Researcher Alison Cobb was just a young girl when she first got interested in zebra stripes, after she watched a documentary which claimed that zebra stripes were for camouflage. She found it to be a rather poor explanation for the stripes, and believed that it is possible that the stripes actually help the zebras to cope with the heat. This was due to her observations of zebras grazing in the midday sun more than the other animals in the same area.

Forty years ago she conducted an experiment wherein she tasked her then young children to crawl around out in the sun while wearing rugby shirts sewed with zebra stripes on the back. Interestingly, they were able to determine which stripes were white and which were black even without seeing them, because the white stripes were considerably cooler.

Zebra Stripes Experiment

In 2003 on her 70th birthday, Cobb conducted another experiment with her husband Stephen Cobb, when they went to Africa and measured the white and black stripes on various parts of captive zebras every 15 minutes throughout the day. Amazingly, they found that temperatures on the black and white stripes differed greatly, with the greatest differences measured on the hottest time of the day. Furthermore, they also noted that zebras tend to stick out their black hair up during the hottest points of the day.

The couple believes that it is possible that zebra stripes actually help the creatures to dissipate and regulate heat, and that the way that the black hairs rise while the white hairs stay flat may be a mechanism that also helps with thermoregulation.

“The data and observations in this paper suggest that the primary function of the stripes may be thermoregulation and a secondary benefit, fly-deterrence,” the couple notes.

On that note, other experts do not entirely agree that thermoregulation is the primary function of zebra stripes. However, they do agree that there is probably no one single reason that zebras evolved to have them.

The study is published in the Journal of Natural History.