Laughter is primal. No one teaches another how to laugh, yet humans somehow just know how to do it, even before learning to speak. Other primates, dogs, hyenas, even rats have been known to laugh.
Laughter is social. Humans especially like to laugh with family and friends.
Laughter is infectious - sometimes just hearing other people laugh can inspire a chuckle or giggle. And how often have you experienced something hilarious when you were alone and you just couldn't wait to tell someone?
Laughter is unique. So it should come as no surprise that scientists and researchers take laughter quite seriously.
Over decades of research, neuroscientist Robert Provine, a professor with the University of Maryland Baltimore County, has boiled laughter down to its basics.
"All language groups laugh 'ha-ha-ha' basically the same way," he said. "Whether you speak Mandarin, French or English, everyone will understand laughter. ... There's a pattern generator in our brain that produces this sound."Provine also says that laughter is mostly about social responses rather than reaction to a joke. Some studies suggest that only 10%-20% of laughter is generated by anything resembling a joke. The other 80%-90% are in reaction to dull non-witticisms that aren't meant to be funny. Some people even laugh at inappropriate times when they don't mean to.
Each "ha" is about one-15th of a second, repeated every fifth of a second, he said. Laugh faster or slower than that and it sounds more like panting or something else.
"Laughter isn't under our conscious control," says Provine. "We don't choose to laugh in the same way that we choose to speak."Unlike speech, laughter isn't completely a form of self-expression. One function of laughter may be to trigger positive feelings in other people. When you laugh, the people around you might start laughing in response. After some time and some chuckles, a whole group of people can become cheerful and relaxed. Laughter can ease tension and foster a sense of unity. This would have been very important for small groups of early humans.
"Laughter above all else is a social thing," Provine said. "The requirement for laughter is another person."Studies of laughter in rats could help further the study of laughing humans. How does one make a rat laugh? It turns out rats love to be tickled. They return again and again to the hands of researchers tickling them. How cute is that?
Northwestern University biomedical engineering professor Jeffrey Burgdorf has found that laughter in rats produces an insulin-like growth factor chemical that acts as an antidepressant and anxiety-reducer. The same thing probably happens in humans, too. This would give doctors a new chemical target in the brain in their effort to develop drugs that fight depression and anxiety in people.
While studying laughter is serious work to researchers, it sounds silly when they're seeking research grants. For that reason, Northwestern's Burgdorf avoids the word "laughter." He calls it "positive emotional response."
Sara Duane is a freelance writer in the Twin Cities area of the great state of Minnesota.