They take a completely original approach, stepping back from one species of zebra and attempting to account for the differences in patterning across different species and subspecies of zebras, horses and asses. Is there anything about the habitat or ecology of these different equids that hints at the function of stripes?

“I was amazed by our results,” says Caro. “Again and again, there was greater striping on areas of the body in those parts of the world where there was more annoyance from biting flies.” Where there are tsetse flies, for instance, the equids tend to come in stripes. Where there aren't, they don't.