Zebra stripes give these equids a unique look, but the purpose of these distinctive markings has remains a question. Some biologists believed the stripes were utilized by the animals to regulate heat, while others thought the markings could help the animals avoid biting insects. Still other researchers theorized the stripes could create an optical illusion as herds run, assisting them in avoiding predators.
Regional variation in pattern of striping could not be entirely explained using any of those previous theories, leading researchers to attempt to find another explanation.
Equus quagga, otherwise known as plains zebras, are native from eastern South Africa to southern Ethiopia. Some of the animals have wide black and white stripes over their entire bodies, while others show thinner markings, which do not extend to the legs. Similar differences in pigmentation and markings are found in various species of animals.
"Thus, humans living where there is an abundance of ultraviolet light have darker skin, and fruit flies found at high altitude have darker exoskeletons," Virginia Morell wrote in an article for Science Magazine.
University of California researchers worked with colleagues from around the world, studying zebras at 16 locations around the world. Markings were noted on the animals in each region, and this data was then compared to records of 29 environmental conditions in each location. The best correlation for striping was found when compared to temperature.
"[W]e found that temperature successfully predicts a substantial amount of the stripe pattern variation observed in plains zebra. As this association between striping and temperature may be indicative of multiple biological processes, we suggest that the selective agents driving zebra striping are probably multifarious and complex," Brenda Larison and Ryan J. Harrigan of the University of California, along with others, wrote in an article detailing their findings.
Instead of just one reason for stripes, these unique markings could provide zebras with several advantages in the wild. However, two of the traditional ideas for the purpose of the stripes - avoiding predators and flies - were largely discounted by the current study.
Three species of zebras may be found around the world - the plains zebra, mountain zebra, and Grévy's zebra. The animals can be found living in grasslands, savannahs, mountains and other terrains. Zebras generally live in small herds or harems, and evolved from old world horses roughly four million years in the past.
How the zebra got its stripes: a problem with too many solutions, an article detailing the study of possible advantages of stripes for zebras, was published in the journal Royal Society Open Science.
