Provine is one of the few researchers trying to go beyond anecdote and speculation by looking at laughter as an animal behaviourist might study birdsong or a wolf's howl. He believes that, like birdsong, laughter functions as some kind of social signal. And others would agree. Indeed, studies have shown that people are thirty times more likely to laugh in social settings than when they are alone, in the absence of pseudosocial stimuli like television. To many researchers, laughter is about strengthening social bonds.
Laughter occurs when people are comfortable with one another, when they feel open and free.
In 1962, for example, an epidemic of laughter among schoolgirls in Tanganyika lasted for six months and forced officials to close schools.