Selective and Evolutionary Aspects of Animal Play

Earlier literature of play is interpreted as a dialogue between functionalists, whose primary concern is with cause, mechanism, or purpose, and structuralists, who stress the form and temporal patterning of behavior. The functionalist view of play as scientific research performed by animals is contrasted with the structuralist view of play as that aspect of behavioral ontogeny in which partially or totally mastered responses are varied and combined into new sequences. Play appears to constitute behavioral experimentation and may contribute behavioral variation to evolution in higher vertebrates. Recent experiments with human children and with model systems support these hypotheses. Selection for playfulness as such is a possibility and may occur even when observational learning provides a mechanism for transmission of new behaviors from innovator to unrelated conspecifics.