Laughter plays a crucial role in every culture across the world. But it\u2019s not clear why laughter exists.<\/p>\n
While it is evidently an inherently social phenomenon \u2013 people are up to 30 times more likely to laugh in a group<\/a> than when alone \u2013 laughter\u2019s function as a form of communication remains mysterious.<\/p>\n A new study<\/a> published in the Proceedings of the National Academy of Sciences, and involving a large group of researchers led by Gregory Bryant from UCLA, suggests that laughter may indicate to listeners the friendship status of those laughing. The researchers asked listeners to judge the friendship status of pairs of strangers and friends based on short snippets of their simultaneous laughter.<\/p>\n Drawn from 24 different societies, they found that listeners were able to reliably distinguish friends from strangers, based on specific acoustic characteristics of the laughter.<\/p>\n In order to unravel how this is possible and what the true meaning of laughter is, we need to delve back into its early origins.<\/p>\n Spontaneous laughter, which is unintentionally triggered by conversation or events, emerges in the first few months of life, even in children who are deaf or blind. Laughter not only transcends human cultural boundaries, but species boundaries, too: it is present in a similar form in other great apes. In fact, the evolutionary origins of human laughter can be traced back to between 10 and 16m years ago<\/a>.<\/p>\n While laughter has been linked to higher pain tolerance and the signalling of social status<\/a>, its principal function appears to be creating and deepening social bonds. As our ancestors began to live in larger and more complex social structures, the quality of relationships became crucial to survival<\/a>. The process of evolution would have favoured the development of cognitive strategies that helped form and sustain these cooperative alliances.<\/p>\n Laughter probably evolved from laboured breathing during play such as tickling, which encourage cooperative and competitive behaviour in young mammals. This expression of the shared arousal experienced through play may have been effective in strengthening positive bonds, and laughter has indeed been shown to prolong the length of play behaviours in both children and chimpanzees, and to directly elicit both conscious and unconscious positive emotional responses<\/a> in human listeners.<\/p>\nLaughter\u2019s evolutionary past<\/h3>\n