How the Zebra came to have stripes has eluded scientists for all time, up until now apparently. It seems that the African blood-sucking flies that carry blood-borne illnesses among other things, are attracted to reflected sun light that is polarized in a plane that is parallel to the ground. It turns out that most warm-blooded animals have coats that reflect light this way. The Zebra's vertical stripes, however, reflect sun light polarized in a vertical plane and the flies don't like it.
In conversations with my son about why living things are the way they are, I've always told him to apply the caveman/saber-toothed tiger example to the question....or in this case the zebra/blood-sucking fly example. That is, if a genetic mutation helps the caveman not get eaten by the tiger, then it will remain in the genes of that civilization until everybody benefits from it.
Every physical characteristic every living thing has can be explained by thinking about how it makes life easier on a dangerous planet, with predators, temperature and light fluctuations, and gravity.
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