Evolution, Structure, and Functions of Human Laughter

Human laughter constitutes a family of nonverbal social vocalizations phylogenetically related to play vocalizations in nonhuman animals. The evolution of articulated speech introduced a second pathway for vocal signaling, including volitional laughter, that afforded multiple interactive functions manifesting in conversational turn-taking and group contexts. Most social functions of laughing relate to coalitional social strategies, including the development of extended social ties for successful long-term cooperative relationships. Laughter provides a unique window into human vocal signaling and cooperative behavior, as well as an example of how ancestral communicative behaviors become integrated with later evolving systems.