This article originally appeared in the March-April issue of mental_floss magazine. If you'd like this kind of thing mailed to your house, get a free issue!

by Judy Dutton

Photo credit: Jonathan Hanson

Robert Provine isn't funny. His wife often frowns at his jokes. But the man knows how to bag a laugh.

Audio recorder in hand, he prowls campuses, malls, zoos, parking lots—wherever he hears the potential for a chuckle. He anticipates the sound, waiting to trap it, hoping to drag each individual laugh back to the lab for analysis. And he knows the tricks. Provine will walk up to strangers point-blank and ask them to laugh into his recorder. He’ll take a charity laugh, or even the nervous kind that people blurt out after saying, “I can’t laugh—you’re not funny.” He’s used sitcoms and laughing gas as bait. Tickling isn’t beneath him.

In his lab, Provine feeds the laughter into a sound spectrograph, analyzing the frequency, amplitude, and length of each sample. In more than 30 years of fieldwork he’s collected an astounding amount of data. He knows that “laugh notes” (such as “ha,” “ho,” or “heh”) have a duration of 75 milliseconds, separated at regular intervals of 210 milliseconds. He’s found that babies laugh 300 times a day, while adults laugh only 20 times. And he knows that laughter peaks at around five years of age. In a study of the “Giggle Twins,” two identical twins who were separated at birth and reunited 43 years later, Provine says, “Until they met each other, neither of these exceptionally happy ladies had known anyone who laughed as much as she did.” He used the example to show how laugh patterns and genetics are linked.

So, what’s his motivation? Why does this bespectacled psychology professor walk around stalking laughs? Because he wants to understand why we do it.

The answer seems obvious: We laugh because something’s funny. Not so, says Provine—and he’s got proof.

Laughing So Hard You Can't Stop

It was back in the mid-1980s, as a young professor at the University of Maryland, Baltimore County, that Provine first became hung up on the neurological underpinnings of laughter. To understand the phenomenon, he collected over 1,200 “laugh samples.” His preferred method: skulking around campus and listening in on conversations. “I’d find a place where people were drifting by, like the line at the dorm cafeteria, and jot down notes,” Provine recalls. As he’d expected, peals of laughter followed one-liners like “You smell like you had a good workout” or “Do you date within your species?”

What Provine didn’t anticipate, however, was that nearly 90 percent of the giggles would be triggered by mundane remarks. Phrases like “I see your point” or “I’ll see you guys later” were being rewarded with laughter. What was it about these dull statements that made people laugh?

“It suddenly occurred to me that I had learned something important,” Provine says. Building off his research, Provine theorized that laughter was being used as a social lubricant; we use it to bond with others. This notion supported other aspects of his field research. It explained why people laugh 30 times more often in the presence of others than they do when they’re alone. It also explained why nitrous oxide (a.k.a. laughing gas) won’t crack you up when inhaled in solitude.

Since then, Provine has made other staggering advances in the field of laugh science. For instance, he’s actually proved that laughter is contagious. Consider the case of the “laugh epidemic” that swept through what’s now Tanzania in 1962. In the small town of Kashasha, three girls started giggling. Soon, the snickers rippled outward to 95 students, lasting for hours before dying down, then erupting again—for three months straight. The school closed down, briefly reopened, then shut down again after the laugh bug reinfected 57 students. Within ten days, laugh attacks plagued 217 kids in the nearby town of Nshamba, then 48 more in Bukoba. It continued to spread, closing 14 schools and afflicting about 1,000 people, before quarantines were put in place. A year and a half passed before this laughathon tailed off.

For the 50 years since, people have been wondering how such a thing could occur. In his lab, Provine instructed volunteers to listen to recordings of positive sounds, like cheering and laughing, and negative sounds, like screaming and retching. Using MRI scans, he showed that hearing laughter activates the brain’s premotor cortex, preparing the facial muscles to smile and laugh in kind; thankfully, screaming and retching don’t inspire the same mimicry.

Laughter’s self-perpetuating powers also explain more modern-day phenomena, including the use of laugh tracks on sitcoms. Canned guffaws first debuted in a 1950 comedy called The Hank McCune Show to give TV viewers the sense that they weren’t alone. But the sounds had a second benefit—the effect cued audiences to laugh when jokes weren’t obvious enough. As Provine explains in his book, Laughter: A Scientific Investigation: “Yes, [TV execs] are often desperately trying to wring some humor out of pathetic scripts, but the overall pattern of their efforts has a basis in reality. Most real-life laughter follows ordinary statements—laughter is more about social relationships than jokes.” As he puts it, “Your life with its own laugh track is like a vast unending sitcom produced by a very ungifted writer.”

Tickled Pink

Oddly enough, the public has strong opinions about what Provine should and shouldn’t research. One day, when he was giving a lecture at a local museum, a female audience member pulled him aside and said, “I certainly hope you’re not studying tickling.” When Provine asked why, she said, “It’s a repulsive, unpleasant behavior.” The comment had the opposite effect. “I thought, ‘Gee, this must be really important to have generated such a strong response,’” he says.

Provine distributed a 52-item questionnaire to over 400 people, asking who tickled whom and how they felt about it. Thirty-five percent of respondents had been tickled in the past week, 86 percent in the past year. Most people enjoyed tickling others—thus the success of the Tickle Me Elmo doll—and while many claimed they hated being on the receiving end, it was more like a love-hate relationship: They’d run off screaming but come back for more. Provine also found that tickling mysteriously disappears after age 40, most likely because that’s when children move out of the house and couples have less sex (tickling is often a form of foreplay). As Provine asks, “How many 80-year-olds get into tickle battles?”

Soon, it dawned on Provine that tickling was an easy way to study laughter in other species like monkeys—so he flew to the Yerkes National Primate Research Center in Atlanta and asked to tickle a few of the residents. To his relief, the center humored his request, allowing him to observe as trainers tickled a chimp named Josh. Provine concluded that the “ha ha” of modern laughter evolved from the “pant pant” of primates during rough-and-tumble play. It also led Provine to identify the world’s first joke. “My candidate for the most ancient joke is saying ‘I’m gonna get you,’ then tickling them,” says Provine. “It’s the only joke you tell to a human baby and a chimpanzee.”

The Best Medicine (Really!)

As Provine has learned, laughing isn’t just about social lubrication and amusement; it also has a dark side. For class one day, he brought in a laugh box—a device that emits a crazed cackling at the push of a button. Provine pushed it, then asked his students to note whether they laughed. At first, nearly half of them did. “But by the tenth time, no one was laughing, and no one liked it,” Provine says. He stashed the laugh box in his office, but had to remove it after a few coworkers began swinging by to push the button. The crazed laughter was driving him to the brink of violence.

This irritation underscores laughter’s less pleasant aspects, like its ability to signal social dominance. In one study of a psychiatric ward, the senior staff often made junior staff the butt of their jokes. Rather than dish it back, the junior staff passed the negative behavior on, poking fun at their patients.

Clearly, laughter can hurt, but its healing powers are equally potent. In 1976, a newspaper editor named Norman Cousins came down with a painful degenerative disease that was initially diagnosed as ankylosing spondylitis. As his condition worsened, he checked into a hotel and treated himself with a regimen of vitamin C, Marx Brothers films, and episodes of Candid Camera. Ten minutes of belly laughs calmed his pain for two hours; within weeks, his disease mysteriously faded into remission.

It’s stories like these that keep Provine intrigued. Even after years of scrutiny, he admits that laughter remains a squirrelly subject, with certain aspects eluding his grasp like a hilariously greased pig. For example, we can’t force ourselves to laugh. Like sneezing, or crying, or yawning, laughter just happens. These days, Provine is examining the use of laughter online, and how it surfaces through comments like LOL (Laughing Out Loud). He also plans to run brain scans of people laughing—a hot area of research that many scientists are exploring. Still, the original laugh tracker prefers basic tools. “Just because something is simple and doesn’t require fMRIs or supercolliders doesn’t make it trivial,” Provine says. “All you need is a pencil and pad of paper.”

This article originally appeared in the March-April issue of mental_floss magazine. If you'd like this kind of thing mailed to your house, get a free issue!