Selection for Optimal Age-Dependent Schedules of Play Behavior

Abstract

Positive and negative effects of play behavior are modeled in a life-historical cost-benefit framework in order to derive predictions about optimal age-dependent scheduling of play. The model predicts that not all animal species will exhibit play behavior, that play should be more frequent in K-selected species than in r-selected species, that younger animals should tend to devote more time and energy to play than older animals, that adults of some species should play, and that in the ontogeny of animals exhibiting play, behavior patterns required in adulthood should appear in play as soon as or soon after they appear in the animal''s general behavioral repertory. Alternative optimal strategies, one or more including play and one or more excluding play, may frequently evolve in different subpopulations of the same species in the same environment. The role of random processes in the evolution of life-history strategies and life-table schedules, and in the evolution of play and perhaps of other social behaviors, may be substantially greater than previously supposed. Data on play behavior in additional species are of interest in the context of these predictions.