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While laughing adds a level of communication to conversation, it can also create a wordless bond across a room. As much as we might dread an attack of the giggles in the middle of a poetry reading or a eulogy, it can also be a lot of subversive fun--particularly when the bug spreads to the person sitting next to you.
The infectious nature of laughter is behind the idea of the laugh track--humor's Muzak--and while canned yuks ought to have all the freshness and appeal of canned peas, they work. "Early television planted people in live audiences and they'd laugh on cue," says Lee Berk, professor of pathology and anatomy at Loma Linda University in California. "Now we have the laugh track instead."
A far easier way to get a laugh--if harder to pull off at parties--is tickling. Nearly all of us are at least a little ticklish, but far and away, the best tickle targets are babies. Behaviorally speaking, that makes sense. If ever there was a two-way pleasure street, it's the delight a baby takes in being tickled and the joy the parent experiences in the tumble of laughter it elicits. In a relationship in which verbal conversation is necessarily at a minimum, that is a great way to make a connection.
But there's more than bonding going on when we tickle. There's learning too. It's no coincidence that the parts of the body that are most ticklish are also the most vulnerable--the stomach, the throat and the groin region where the femoral artery lies. Best to learn early that when those areas get touched, you pull away or tuck in your chin. And best to make it a joy for parents to provide that lesson, if only to make sure that they teach it often and you learn it well.
"This may explain why we lose our taste for being tickled as we get older," says human ethologist Glenn Weisfeld of Wayne State University in Detroit. "By adulthood we've learned how to counter unwanted thrusts."
Laughter may protect us from not only predators but also disease. One of the reasons doctors prescribe exercise for their patients is that even light exertion can increase heart and respiration rate, oxygenate the system and reduce levels of stress hormones. As long ago as the 1980s, Berk began suspecting that a good burst of laughter might do the same.
In order to test his idea, he recruited 10 volunteers and drew three samples of their blood before they watched a one-hour comedy video. He then took another sample every 10 minutes during the video and three more after. For comedy-club owners looking for ways to get the laughs rolling, mandatory blood tests might not be the best idea, but they served Berk well. Laughter, he found, indeed appeared to turn down the spigot on stress chemicals--cortisol, the primary stress hormone, most significantly.
In a follow-up study in 2001, he tracked two groups of cardiac patients for a year after a heart attack. One group was asked to watch 30 minutes of comedy a day as an adjunct to medical therapy; the other received the medical care alone. At the end of the year, the laughing group had lower blood pressure, lower stress-hormone levels, fewer episodes of arrhythmia and, most important, fewer repeat heart attacks. "Laughter is a form of internal jogging," Berk says. "What a nice way to get the lungs to move and the blood to circulate."