Steven Pinker -- How the Mind Works - Hampshire High Italian ...

546 j HOW THE MIND WORKSto continue. And laughter is contagious. The psychologist RobertProvine, who has documented the ethology of laughter in humans, foundthat people laugh thirty times more often when they are with other peoplethan when they are alone. Even when people laugh alone, they areoften imagining they are with others: they are reading others' words,hearing their voices on the radio, or watching them on television. Peoplelaugh when they hear laughter; that is why television comedies use laughtracks to compensate for the absence of a live audience. (The rim shot ordrumbeat that punctuated the jokes of vaudeville comedians was a precursor.)All this suggests two things. First, laughter is noisy not because itreleases pent-up psychic energy but so that others may hear it; it is aform of communication. Second, laughter is involuntary for the samereason that other emotional displays are involuntary (Chapter 6). Thebrain broadcasts an honest, unfakable, expensive advertisement of amental state by transferring control from the computational systemsunderlying voluntary action to the low-level drivers of the body's physicalplant. As with displays of anger, sympathy, shame, and fear, the brain isgoing to some effort to convince an audience that an internal state is heartfeltrather than a sham.Laughter appears to have homologues in other primate species. Thehuman ethologist Irenaus Eibl-Eibesfeldt hears the rhythmic noise oflaughter in the mobbing call that monkeys give when they gang up tothreaten or attack a common enemy. Chimpanzees make a differentnoise that primatologists describe as laughter. It is a breathy pant madeboth when exhaling and when inhaling, and it sounds more like sawingwood than like the exhaled ha-ha-ha of human laughter. (There may beother kinds of chimpanzee laughter as well.) Chimps "laugh" when theytickle each other, just as children do. Tickling consists of touching vulnerableparts of the body during a mock attack. Many primates, and childrenin all societies, engage in rough-and-tumble play as practice forfighting. Play fighting poses a dilemma for the fighters: the scufflingshould be realistic enough to serve as a useful rehearsal for offense anddefense, but each party wants the other to know the attack is a sham sothe fight doesn't escalate and do real damage. Chimp laughter and otherprimate play faces have evolved as a signal that the aggression is, as wesay, all in fun. So we have two candidates for precursors to laughter: asignal of collective aggression and a signal of mock aggression. They arenot mutually exclusive, and both may shed light on humor in humans.