Scientists have found a reason why Zebras have stripes while horses and donkeys don't.

The black and white stripes present in Zebra can help ward off flies as they roam in the grasslands, according to a research done by Tim Caro, a behavioural ecologist at University of California-Davis. The researchers put a coat with stripes similar to zebras over horses and they were able to note the fewer number of flies landing on them. Although flies were attracted to zebras as much it was on horses and donkeys, fewer of them landed and most of them bounced off from it. The earlier hypothesis was that black and white stripes may have enabled zebras to camouflage in the face of an attack in the grasslands.

The new research may help mankind devise new clothes mimicking the zebra stripes to ward off flies while going to forests or for trekking in grasslands. Zebra stripes are already in use on the roads to help pedestrians cross the road safely and also easily visible to motorists from a distance.

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0210831