Why We Laugh

Whether it's the giggling of your child or the enthusiastic hollers of a talk show's studio audience, we hear laughter every day. Nothing could be more common. But just because it's common doesn't make laughter any less strange.

For instance, the next time you're at the movies enjoying some comedy blockbuster, listen hard to the laughter around you. Why are all these strangers, in unison, exploding into such weird, gasping, grunting noises? Their laughs may suddenly stop seeming familiar, and more like the inhuman chatter of birds or the screeches of monkeys at the zoo.

Once you start looking at laughter as behavior, it can lead to some odd questions. Why do we do it? Do animals laugh? And why do we expect that any decent James Bond villain will cackle diabolically when revealing his plan for world domination? What's so funny?

To answer these and other mysteries of laughter, WebMD delved into the surprisingly contentious world of laughter research.

Why Do We laugh?

The answer may seem obvious: We laugh when we perceive something funny. But the obvious answer is not correct, at least most of the time.

"Most laughter is not in response to jokes or humor," says Robert R. Provine, a professor of psychology and neuroscience at the University of Maryland Baltimore County. Provine should know. He has conducted a number of studies of laughter and authored the book Laughter: a Scientific Investigation. One of his central arguments is that humor and laughter are not inseparable.

Provine did a survey of laughter in the wild -- he and some graduate students listened in on average conversations in public places and made notes. And in a survey of 1,200 "laugh episodes," he found that only 10%-20% of laughs were generated by anything resembling a joke.

The other 80%-90% of comments that received a laugh were dull non-witticisms like, "I'll see you guys later" and "It was nice meeting you, too." So why the laughs?

Provine argues it has to do with the evolutionary development of laughter. In humans, laughter predates speech by perhaps millions of years. Before our human ancestors could talk with each other, laughter was a simpler method of communication, he tells WebMD.

It's also instinctual. "Infants laugh almost from birth," says Steve Wilson, MA, CSP, a psychologist and laugh therapist. "In fact, people who are born blind and deaf still laugh. So we know it's not a learned behavior. Humans are hardwired for laughter."

But perhaps because laughter is so ancient, it's much less precise than language.

"Laughter isn't under our conscious control," says Provine. "We don't choose to laugh in the same way that we choose to speak." If you've ever had an inopportune laughing fit -- in a lecture, during a high school play, or at a funeral, for instance -- you know that laughter can't always be tamed.