The Humor Code (14 page)

But the laughter episodes here in Tanzania don't seem to have anything to do with these ailments. A. M. Rankin and P. J. Philip, the doctors who wrote about the situation in the
Central African Journal of Medicine
in 1963, tested for infections, viruses, food poisoning, and waterborne diseases. They found nothing.
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Plus, in many of these other conditions, uncontrollable laughter leads to far more serious side effects. In Tanzania, the laughter just led to more laughter. Or as Rankin and Philip put it, rather dryly, “No fatal cases have been reported.”

One evening, maybe to make up for all the dead ends in Bukoba, Rutta takes us for a night on the town. He directs us into the dark, smoky back room of a downtown Bukoba bar where, on a cleared-out
space in the center of the floor, women take turns dancing to African pop songs in skimpy outfits and heels. The place reeks of grilled meat, courtesy of a closet-like kitchen in the corner, where a sweat-drenched cook is churning out endless plastic trays heaped with charred flesh. In between musical numbers, the women hurry behind a curtain hanging from the back wall and reappear a few moments later in a full costume change. At one point, a dancer emerges in a plaid shirt and cowboy boots and performs a country line dance to Dolly Parton's “Coat of Many Colors.” The operation resembles a chaste if still misogynistic version of an American strip club. And eventually, to spice it up, the women decide to make the only two
mzungus
here part of the show. So one by one, Pete and I get pulled into the spotlight.

That's how we find ourselves on stage at an African burlesque show, staring at a room of frowning men gnawing on blackened animal pieces and wondering what the hell we're doing up here, blocking their view. And so we dance. Pete waltzes with one of the dancers like he's Al Pacino in
Scent of a Woman
. I play coy with the ladies on stage and shake my butt at the audience. Pete trots out “the lasso,” twirling an invisible rope and using it to capture one of the dancers. All for the sake of science.

We return to our seats amid the sounds of chuckles and claps. We weren't the sexiest dancers to grace the stage, but we were the funniest. And that has to count for something, since humor wouldn't have evolved in humans if it wasn't appealing from a sexual-selection standpoint—if it weren't, at some level, “sexy.”

Sure enough, a survey of 700 men and women discovered that people considered humor among the most important of all characteristics when choosing a partner, romantic or otherwise.
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And studies of happy marriages, especially those lasting more than a half century, find spouses often ascribe their marital bliss in part to laughing together.
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This finding makes sense, says Pete: if you and your partner can make each other laugh, that suggests you have a similar sense of humor and therefore share compatible values, beliefs, and interests. Plus you're both adept at making the other person happy.

Unfortunately, research also suggests the opposite: humor can signal doom for a relationship. Studies have found that dating couples
who exhibit strong senses of humor—and not mean-spirited humor, mind you, but positive and friendly humor—are more likely than others to break up. As paradoxical as that sounds, it's not absurd. Since humor is such a highly regarded personal trait, it's more likely that others will be enticed by these attractively funny people and will lure them away from their partners.
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But what, exactly, is evolutionarily attractive about a sense of humor? What use from a survival-of-the-species perspective is the ability to recognize what's funny and then bark about it? Some evolutionary theorists have posited that humor must have developed to demonstrate intelligence and creativity through wit, while others see laughter as a vocal adaptation of social grooming, a way to build bonds with one another without having to pick critters off each other's hides. The list of theories goes on: laughter could have been a “disabling mechanism,” a way to signal that poking that crocodile with a stick is so laughable it might threaten our genetic survival. Or it could have been a way to determine winners and losers on the social strata—differentiating between those who deserve to laugh at others and those who deserve to get laughed at without resorting to prehistoric gladiator battles.
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Or it could have been a signal of false alarm, a vocal demonstration that the rustling in the bushes wasn't a saber-toothed tiger as expected, just a harmless antelope.
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One of the newest theories suggests that laughter could be the brain's version of an error message, that it evolved as a way for the mind to notice, reward the discovery of, and verbally signal mistaken leaps to conclusion.
¹¹

All these ideas are compelling in their own ways, but most lack hard evidence to verify their claims. If Pete were a betting man, he'd put his money on an idea put forward in 2005 by an undergrad named Matthew Gervais and his advisor, evolutionary biologist David Sloan Wilson, at Binghamton University in New York. In 29 heady pages in the
Quarterly Review of Biology
, the two wove together findings from neuroscience and positive psychology and multilevel selection theory to synthesize a novel and compelling account of how and why we developed the ability to laugh. It's the sort of virtuoso academic performance that makes a science geek like Pete gush, “That paper is amazing.”

What's possibly most intriguing of all about their theory is that its key piece of evidence originated, of all places, from the work of a quirky nineteenth-century fellow named Guillaume Duchenne, a guy who went around zapping people's faces with electrodes. Duchenne, a French physician, became obsessed with figuring out what happened to human bodies when he shocked them with the hot new gizmo of the time: a portable battery and induction cable. Luckily for him, he worked at a women's hospice, so he had access to a lot of prone bodies to zap. He must have been quite the charmer. All the ladies wanted to be electrocuted by the “little old man with his mischief box.”

Applying the prongs of his mischief box to people's faces, Duchenne evoked and captured one kind of smiling—the voluntary kind, the type of expression we produce when we grin or chortle to be polite. This mannerism, he discovered, involves the face's zygomatic major muscles raising the corners of the mouth. But Duchenne discovered there was a second variety of smiling and laughing, one that occurs when we find something truly entertaining or funny. This expression was more complex, utilizing both the zygomatic major muscles and the orbicularis oculi muscles that form crow's feet. It's why people say a real smile is in the eyes. Duchenne was never able to reproduce with his electrodes this second form of expression, now known as a Duchenne smile or Duchenne laughter, and he came to believe it was “only put at play by the sweet emotion of the soul.” It was one of many scientific discoveries by the erstwhile electrocutioner, though Duchenne might have taken things too far in his book
The Mechanism of Human Physiognomy
. He had a beautiful model pose as Lady Macbeth while he zapped her face into different theatrical expressions.
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More than a century later, Gervais and Wilson saw Duchenne's discovery as evidence that laughter evolved at two different points in human development. First, they posited, at a point sometime between 2 and 4 million years ago came Duchenne laughter, the kind triggered by something funny. An outgrowth of the breathy panting emitted by primates during play fighting, it likely appeared before the emergence of language. This sort of laughter was a signal that things
at the moment were okay, that danger was low and basic needs were met, and now was as good a time as any to explore, to play, to start laying the social groundwork that would lead to civilization. And this part of laughter's evolution could tie with Pete's idea that humor is elicited by benign violations, said Gervais, now a doctoral candidate in biological anthropology at UCLA. “There could be a violation or incongruity of expectation going on, but what's being signaled by the laughter is that it's not serious, or it's benign,” Gervais told me. “What the humor is indexing and the laughter is signaling is, ‘This is an opportunity for learning.' It signals this is a non-serious novelty, and recruits others to play with and explore cognitively, emotionally, and socially the implications of this novelty.

“I think it's an important part of the human story that humans are learners,” he continued. “And something like an appreciation of humor is a process that encouraged exploration and learning for a species that has a brain built to learn.”

But then, sometime between 2 million years ago and the present, theorized Gervais and Wilson, the other sort of laughter emerged—the non-Duchenne sort, the kind that isn't dependent on something being funny. As people developed cognitively and behaviorally, they learned to mimic the spontaneous behavior of laughter to take advantage of its effects. They couldn't get it right—they couldn't simulate the eye-muscle movements of real laughter and smiling—but it was close. It's similar to the way some moths evolved “owl eye” patterns on their wings to scare away predators—but in the case of non-Duchenne laughter, the point wasn't to scare away, it was to bring others closer. Mimicked laughter was a way to manipulate others, to hot wire their vulnerability to be entertained—sometimes for mutually beneficial purposes, sometimes for more devious reasons. As Gervais and Wilson put it in their paper, “non-Duchenne laughter came to occur in aggressive, nervous, or hierarchical contexts, functioning to signal, to appease, to manipulate, to deride, or to subvert.”
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It's a compelling, if not the most cheerful, account of why we laugh. If Gervais and Wilson are right, what about the laughs we inspired at the African strip club? Were the chuckles the old kind, the involuntarily stuff of genuine amusement? Or the non-Duchenne,
darker version—laughter meant to appease, or worse still, to deride? I'm hoping for the former, but I have a feeling it might be the latter.

Since we're in
Africa, we figure we ought to go on a safari. Rutta is happy to oblige, one morning aiming the van toward Rubondo Island National Park, a 176-square-mile nature preserve off the coast of Lake Victoria. As we zoom up and down the rolling green hills skirting the lake, Pete fires up some Tupac Shakur on his iPod. “In the citaaay, the city of Compton!” sings Rutta, a big hip-hop fan, as we blow past longhorn cattle and vervet monkeys scampering about on the side of the road. “You know,” Rutta says to Pete, “most professors don't act like you.”

“Thank you,” says Pete.

We eventually stop at a small, mud-bedraggled port, where we charter a small red-and-white motorboat to take us across a thin strait to Rubondo Island. Two somber-faced men in gray parkas sit behind us in the boat, armed with sizable old machine guns. We decide not to ask what threat, human or animal, necessitates that kind of firepower. When we reach the island, a four-wheel-drive safari jeep takes us through its densely forested interior. As we rumble down a two-track dirt road, foliage whipping at the windows and overhead vines sliding along the roof, I eye Rutta's stylish camouflage shirt-and-pants combo and safari vest. As usual, he's dressed for this excursion far better than we are.

We hope to spot some of the chimpanzees that inhabit the island, maybe even get a chance to tickle them. As we've noted, it's believed that human laughter evolved from the distinctive panting emitted by our great-ape relatives during rough-and-tumble play to signal it's all in good fun and nobody's about to tear anybody else's throat out. In a clever bit of scientific detective work, psychologist Marina Davila-Ross of the University of Portsmouth in the United Kingdom digitally analyzed recordings of tickle-induced panting from chimps, bonobos, gorillas, and orangutans, as well as human laughter, and found the vocal similarities between the species matched their evolutionary relationships. Chimps and bonobos, our closest relatives,
boasted the most laughter-like kind of panting, while the noises of gorillas, further down our family tree, sounded less like laughing. Orangutans, our truly distant ancestors, panted in the most primitive way of all.
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Even if we don't find one of our hairy relations out here in the jungle, maybe we can at least find a rat or two and tickle them. There are scientific antecedents to support such a venture. In 1997, psychologist Jaak Panksepp entered his lab at Bowling Green State University in Ohio and told undergrad Jeffrey Burgdorf, “Let's go tickle some rats.” The two and their colleagues had already discovered that lab rats emitted a unique ultrasonic chirp in the 50-kilohertz range when they played. Now they wondered if they could prompt these squeaks through tickling. Sure enough, when the researchers began poking at the bellies of the rats in their lab, their ultrasonic recording devices picked up the same 50-kilohertz sounds. The rats eagerly nestled their fingers for more. Soon, as the news media trumpeted the existence of rat laughter, people the world over were opening up their rat cages and engaging Pinky and Mr. Pickles in full-scale tickle wars.
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“I don't necessarily call it laughter; I call it a signal of positive affect,” Burgdorf told us when we visited him at Northwestern University's Falk Center for Molecular Therapeutics in Chicago, where he now works as a biomedical engineering professor. Burgdorf's careful choice of words makes sense. He and Panksepp faced serious critical pushback when their rat-tickling activities first went public. But whatever you want to call it, Burgdorf, a quick-witted guy with a boyish face and a sign on his office door that reads “Know-It-All,” has been obsessed with that strange rat noise he first stimulated in 1997. “How do I know that it's really a sign of positive affect?” he said to us. “That's been the question of my career.”