The five ideas
Scientists have offered five main reasons for the stripes, the Natural History Museum in London says: camouflage, confusing predators, telling one another apart, keeping biting flies off, and controlling body temperature. The debate is not over, but the evidence has gathered behind one of them.
Biting flies
In 2014 a team led by Tim Caro of UC Davis compared where striped zebras, horses and asses live against each idea. Striping matched where biting flies like horseflies are most troublesome, and the study found no consistent support for camouflage, avoiding predators, managing heat or social life.
In 2019 Caro and Martin How of the University of Bristol watched horseflies around zebras and horses on a horse farm. The flies circled both, but far fewer landed on the zebras. Near a zebra, the flies failed to slow down and flew past or bumped into it. When the horses wore striped coats, flies landed on the coats far less, but bit their bare heads as often as ever.
Later Bristol studies found that stark black and white contrast and small dark patches work best against horseflies. Scientists call biting flies the leading explanation, not a settled one.
The ideas that did not hold up
Camouflage: a 2016 study by Caro and colleagues estimated that lions and hyenas cannot make out the stripes beyond about 50 meters in daylight and 30 meters at dusk, and judged it highly unlikely that the stripes hide zebras from predators. The same study found no social advantage.
Cooling: in a 2018 experiment, barrels painted with stripes were no cooler inside than gray ones.
Not everyone agrees. A 2015 study led from UCLA found that temperature predicts much of the variation in zebra striping, and researchers on both sides say more work is needed.
Black with white stripes, or white with black?
Under the coat, zebra skin is black or dark brown, which is why many describe zebras as black with white stripes. San Diego Zoo Wildlife Alliance says it depends on how you look at it.
No two zebras are striped alike. Each pattern is unique, like a fingerprint, which is how researchers tell individuals apart.
Rubs and his stripes
Rubs is the one zebra at Kaleidoscope Desert. Spend time with him and you start to know him by the swirl of stripes on his rump before you ever see his face. He lives with his herd, the six mini horses and two mini donkeys.
Kaleidoscope Desert is a nonprofit art and animal sanctuary on 7.5 acres in Morongo Valley, California, 15 minutes from Joshua Tree and 20 minutes from Palm Springs, where more than 100 animals roam free among the art.
You meet them on the Sanctuary Tour, a guided walk of about 90 minutes that runs daily, with someone who knows every resident by name and their stories. The animals come over on their own terms. Every visit is for adults, 18 and over.
100% of proceeds go to the animals: their rescue, their care, and the sanctuary they live in. Kaleidoscope Desert Foundation is a registered 501(c)(3) nonprofit.