#207--So writes Robert Solposky, author of Why Zebras Don't Get Ulcers. Our nervous system cannot distinguish between a real threat and an imagined one. Thus, unlike the zebra or any animal, once a stress has been removed, humans will often continue to obsess over it. The zebra doesn't hold a grudge against the lion who tried to eat him. And no animal in nature worries about what the other members of the herd are whispering behind her back after a crazy night on the plains. It's only us "intelligent" humans who will sacrifice our very health by taking drugs to medicate this stress away.