Play and playfulness are enigmatic from an evolutionary perspective as it is not obvious that they provide any survival or reproductive benefits. Indeed, animals engaged in play can be injured or even killed, waste energy that could presumably be better put to other uses, or open themselves to predation through reduced vigilance. Play fighting can escalate to real fighting if signals are misread or one player acts too aggressively. But, since play is so common, especially among mammals but also many birds, perhaps other vertebrates such as reptiles, or even certain invertebrates, such as the octopus (Burghardt, 2005), its selective advantages must somehow outweigh these costs.
In a 1998 presentation, Chick proposed that adult human play and playfulness could be explained by sexual selection. In particular, he claimed that males seek playful females for long-term mates because playfulness signals youth, health, and, therefore, fecundity. Females, on the other hand, seek playful males because playfulness is a signal of non-aggressiveness. Chick (2001) therefore referred to this as a signal theory of play.
Adult Play and Sexual Selection
