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Use these social-bookmarking links to share Why we laugh at slapstick. Follow us. Gil Greengross, an anthropologist then at the University of New Mexico, noted that humor and laughter occur in every society, as well as in apes and even rats. This universality suggests an evolutionary role, although humor and laughter could conceivably be a byproduct of some other process important to survival.
Wilson is a major proponent of group selection, an evolutionary theory based on the idea that in social species like ours, natural selection favors characteristics that foster the survival of the group, not just of individuals.
Wilson and Gervais applied the concept of group selection to two different types of human laughter. Spontaneous, emotional, impulsive and involuntary laughter is a genuine expression of amusement and joy and is a reaction to playing and joking around; it shows up in the smiles of a child or during roughhousing or tickling.
This display of amusement is called Duchenne laughter, after scholar Guillaume-Benjamin-Amand Duchenne de Boulogne, who first described it in the midth century. Conversely, non-Duchenne laughter is a studied and not very emotional imitation of spontaneous laughter.
People employ it as a voluntary social strategy—for example, when their smiles and laughter punctuate ordinary conversations, even when those chats are not particularly funny.
Facial expressions and the neural pathways that control them differ between the two kinds of laughter, the authors say.
Duchenne laughter arises in the brain stem and the limbic system responsible for emotions , whereas non-Duchenne laughter is controlled by the voluntary premotor areas thought to participate in planning movements of the frontal cortex. The neural mechanisms are so distinct that just one pathway or the other is affected in some forms of facial paralysis. According to Wilson and Gervais, the two forms of laughter, and the neural mechanisms behind them, evolved at different times.
Spontaneous laughter has its roots in the games of early primates and in fact has features in common with animal vocalizations. Controlled laughter may have evolved later, with the development of casual conversation, denigration and derision in social interactions. Ultimately, the authors suggest, primate laughter was gradually co-opted and elaborated through human biological and cultural evolution in several stages. Between four and two million years ago Duchenne laughter became a medium of emotional contagion, a social glue, in long-extinct human ancestors; it promoted interactions among members of a group in periods of safety and satiation.
Laughter by group members in response to what Wilson and Gervais call protohumor—nonserious violations of social norms—was a reliable indicator of such relaxed, safe times and paved the way to playful emotions.
When later ancestors acquired more sophisticated cognitive and social skills, Duchenne laughter and protohumor became the basis for humor in all its most complex facets and for new functions. Now non-Duchenne laughter, along with its dark side, appeared: strategic, calculated, and even derisory and aggressive. The book grew out of ideas proposed by Hurley. Hurley was interested, he wrote on his website, in a contradiction.
The idea is that humor evolved from this constant process of confirmation: people derive amusement from finding discrepancies between expectations and reality when the discrepancies are harmless, and this pleasure keeps us looking for such discrepancies. It is a sign that elevates our social status and allows us to attract reproductive partners. In other words, a joke is to the sense of humor what a cannoli loaded with fat and sugar is to the sense of taste.
And because grasping the incongruities requires a store of knowledge and beliefs, shared laughter signals a commonality of worldviews, preferences and convictions, which reinforces social ties and the sense of belonging to the same group.
As Hurly told psychologist Jarrett in , the theory goes beyond predicting what makes people laugh. Benign violation can explain why a number of things make us laugh, including being tickled: That is, tickling benignly violates someone's physical space.
You can't tickle yourself because that doesn't constitute a violation and complete strangers can't tickle you to the point of laughter because you won't see it as a benign act. Research in showed that our primate relatives — chimpanzees, bonobos, gorillas and orangutans — all produce laughter-like sounds when tickled as well as when they're wrestling and play-chasing. This suggests that humor and our ability to laugh likely came from humans and great apes' last common ancestor.
And in a follow-up study in , scientists showed that chimpanzees can make silent "laugh faces" just like humans. She points to theories from ancient Greece and Hobbes to explain why some find pain funny -- because it can make the person laughing feel greater than the object of his or her derision. Mahony explained the mindset as, "I laugh in triumph and superiority at the foibles and stupidity of other people. One example of this is the Darwin Awards, a Web site that recounts the exploits of people a few of the stories are real who, through poor decision-making or a seeming lack of common sense, remove themselves from the gene pool.
But Mahony notes that if your own relative or friend made a mistake that put them on the list, you would likely search for a way to justify their actions. Another possible explanation for the humor is the detachment most people feel from the person injured on TV or in an Internet video. In addition to a person they probably don't know personally, the detachment can stem from the situation where the person gets hurt, which is often somewhat outlandish -- like an absurd skateboarding stunt.
He noted that while people may laugh, the person being hurt is typically pained by something they chose to do. Television shows in the United States do not broadcast torture, he noted, a different situation where a person who found it humorous could very well have a deeper psychological issue.
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