> Now the team want to determine why natural selection has driven striping in equids—the horse family—but not other hoofed animals.
Probably some flying stingers that transmitted a lethal disease that these past horses couldn't quickly build resistance to. It could also be that this sickness came in waves with only a few survivors every time, and the patterns on the zebras got amplified on every wave until it reached the current state. In the beginning it may have even been a coincidence that the pattern was there for individuals which survived the plague, but over time as it amplified it transformed into a evolutionary benefit on its own.
Probably some flying stingers that transmitted a lethal disease that these past horses couldn't quickly build resistance to. It could also be that this sickness came in waves with only a few survivors every time, and the patterns on the zebras got amplified on every wave until it reached the current state. In the beginning it may have even been a coincidence that the pattern was there for individuals which survived the plague, but over time as it amplified it transformed into a evolutionary benefit on its own.