Play is not the silly sibling of work and love. Play is built as deeply within people as are work and love. Ethologists have addressed the function of play among the young of many mammalian species The specific behaviors that these youngsters rehearse and perfect in their rough-and-tumble play are precisely those they later use as adults to hunt, to escape predators, and to establish a dominance hierarchy. Said another way, play teaches lessons that make the serious tasks of work and love possible.