Thumbs, Toes, and Tears Read online

  LaughLab didn’t concur precisely with Freud. It concluded that the most compelling reason why so many people found the hunting joke funny was its sharp incongruity. After all, you figure that someone concerned enough about his friend to call 911 in the first place would go back and delicately check his pulse, not shoot him. That’s completely unexpected, and under the circumstances, hilarious because the whiplash is so sharp.

  Darkness in humor and whiplashes in logic seem to be the sources of the most central aspect of laughter: surprise. To be amused, our minds have to be headed in one direction and then yanked unceremoniously in the other.6In that moment of surprise and confusion, as our neurons struggle to process all of the conflicting cues and resolve all of the mixed messages, we suddenly “get” the joke. This is why you can never precisely predict a laugh because we never consciously decide to do it in the first place. Never. A premeditated laugh is a fake laugh, and most of us recognize it instantly when we hear it.

  Wiseman’s LaughLab didn’t simply observe the whiplashing effect jokes have on us, it actually measured it, using functional magnetic resonance imaging to peer into the brains of people as they listened, first, to the initial part of various jokes, and then to the punch lines. Later they compared those images to scans recorded when the same subjects were simply listening to a series of unfunny sentences.

  The scans found that humor and laughter are scattered throughout the brain. There is—cerebrally speaking, at least—no comedy central. We have clusters of neurons devoted exclusively to all sorts of different aspects of laughter and humor—areas for hearing, seeing, and recognizing the laugh of someone else, sectors that distinguish between puns and slapstick humor, and special neurons that send signals to our lungs and pharynx so that we don’t simply feel amused but actually laugh. Yet none of these are bunched together in one spot. This indicates that human laughter has evolved over time, changing from something old to something new, connecting more recently arrived parts of the brain with older areas.

  For example, a semantic joke such as. “What don’t sharks bite lawyers? Professional courtesy,” is initially processed in the temporal lobes, which sit roughly above our ears. Puns, on the other hand, like “Why did the golfer wear two pairs of pants? Because he had a hole in one!” are first processed near Wernicke’s area on the left, verbal side of the brain, presumably because puns are verbal by nature.7 These are the different areas of the brain where we sort through all of the raw information we register and then work out the basic meaning of what we are hearing. But that is only part of the process.

  If people find a joke funny, LaughLab’s MRIs revealed that a very precise area of the brain just above the right eyebrow called the ventromedial prefrontal cortex suddenly lit up. This cluster of neurons is as close as the brain gets to a funny bone. Several brain-scanning experiments have shown that this is where we “see” incongruity, and then register the surprise that makes us laugh.8 It’s the part of the brain that “gets” the joke.9

  It is not, however, the part of the brain that experiences the sensation we call funny. That is situated in still another place, far away, near the base of the brain in an area called the nucleus accumbens, a location, logically enough, associated with positive emotions in animals and identified as a key site in moderating drug addiction. Its location is so close to that area, in fact, that some researchers have wondered if it might help explain why we can never get too much of a good laugh. Fun has its addictive qualities, too, after all.

  There is a final sector of the brain that actually triggers laughter. And it resides in still another location—the selfsame area, in fact, that helps us direct our thumbs and fingers to make tools, and our lungs, throats, and tongues to make words. Scientists call it the supplemental motor area, or SMA. Located near the top of the brain, it was first pinpointed in the late 1990s, when researchers at the University of Rochester School of Medicine performed four humor tests on thirteen people at the same time they scanned their brains. In the first test, each subject was asked to laugh along with the people they heard laughing in a recording. No jokes were involved. It was like listening to a laugh track without a sitcom. In the next experiment the patients were asked to listen to the laughter but not to laugh along. In the third test, they each read written jokes, and in the fourth they viewed a series of wordless cartoons.

  Whenever anybody laughed for any reason, the MRI machines indicated that the SMA was always activated. It seems that this area plays a central role in all kinds of movement—hands, feet, legs, even eyes. In the case of laughter, it gathers up those disparate signals from other parts of the brain that say it is time to laugh and sends impulses to our throats and chests and the fifteen muscles our faces use when we laugh.

  The odd thing is that this part of the brain can trigger laughter even when something isn’t really funny. Surgeons found this out at the UCLA School of Medicine a few years ago when they were performing exploratory surgery on the brain of a sixteen-year-old girl who was suffering from intractable seizures. They placed electrodes in different parts of the girl’s brain to locate the sections that were causing her problems. When neurons were stimulated near the supplemental motor area, they found that she often laughed, even though there wasn’t anything particularly funny going on. When the girl was asked what she found so funny, her answers were reminiscent of the split-brain patients of Michael Gazzaniga who made stories up to explain why they were drawing odd pictures (see chapter 7). If she was reading a story when the brain stimulation made her laugh, for example, she said the passage she was reading was funny, even if it wasn’t. One time when she was simply showing the doctors she could touch the tips of two fingers together, an electrical stimulation made her laugh. When asked why, she answered, “you guys are just so funny … standing around.”10 This might also help explain why some studies have shown that even when we don’t feel happy, smiling can make us feel happier. Our minds apparently tell us, whenever we are laughing or smiling, that we must be happy, and so then we are.

  There is also the strange case of a landscaper from Iowa known in the scientific literature as CB. His affliction recalls those juxtaposed incongruities that seem so important to anything we find funny. CB suffered a stroke at the unusually young age of forty-eight. Thankfully he made a full recovery, except for one perplexing problem. He occasionally, and for no apparent reason, would break into uncontrollable fits of laughter. When this happened, he was almost never experiencing anything funny. In fact, he wasn’t even thinking an amusing thought, nor was he in the company of anyone else who was so much as chuckling. Yet great overwhelming storms of laughter would ambush him. Not only that, at other times he suddenly found himself weeping uncontrollably. Again, he didn’t feel any of the emotions that normally cause us to cry. It just came on, like a cloudburst.

  The affliction that CB suffers from is common enough that it has its own medical acronym, PLC—pathological laughter and crying. All victims of PLC have, for one reason or another, had very tiny parts of their brains damaged related to the supplemental motor area and the pathways through which it dispatches its signals. Somehow or other, neurons are firing that say laugh or cry, but they aren’t being prompted by the parts of the brain that actually process the emotions that cause genuine laughter or tears.

  Most of us don’t suffer from this problem, but it’s interesting that a central theory about the origin of laughter and the whiplashing effect that is perceived in our prefrontal cortex can be traced back to the neurological locations associated with laughing and crying. On closer inspection, it turns out that there might be a good deal more to this connection than coincidence.

  …

  Darwin noticed that the facial expression of a person laughing often looked identical to someone who was crying. But it was the British zoologist Desmond Morris who first speculated in his popular book The Naked Ape that the origin of laughter might actually be directly linked to crying.

  In the earliest months of life we have one
primary way of expressing fear, loneliness, pain, or any other discomfort: We bawl, long and loudly. It is a simple way of making our point, but highly effective. Any parent can tell you that.

  During our first ninety days, we do this indiscriminately. Pretty much any adult will do as long as he or she fixes the baby’s problems—fresh diaper, food, warmth. At this point in life, all faces appear neutral, and therefore good because infants at this age simply don’t have the cognitive firepower to know the difference between a familiar face and a strange one.

  But then around the fourth month, at some very basic level, the brain begins to wire up connections that enable us to recognize the primary caregivers in our lives. This is also the age at which we begin to smile and giggle, an immense milestone in human relationships. Mothers and fathers live for a child’s first laugh, because it marks their offspring’s relationship to them as personal, not just practical; as if the child is saying, “I know you! You are special!” Their child is reacting not simply to basic, faceless needs like an empty stomach, but to Mom and Dad themselves. That produces a powerful bond.

  Looked at this way, you can view a baby’s laugh as a survival technique. Since human babies are essentially born twelve months early compared with other primates, we enter the world the most helpless mammals on the planet. We require prodigious doses of parental commitment and care. We are easily injured; we are unable, literally, to hold our heads up for months and incapable of navigating. We demand coddling, feeding, and attention day and night.

  But a baby’s laugh provides a powerful emotional gift that encourages her care. The more laughter, the more bonding; the more bonding; the better the chances of survival. It sparks a potent feedback loop. This may explain why across every culture, parents play with their babies to encourage them to laugh.

  But what could have put this play-laugh feedback loop in motion in the first place? Morris explains it this way: imagine you are a prehistoric four-month-old cruising along in the arms of your mother when suddenly you are startled. Being four months old, your immediate reaction is to cry. But in another split second you realize everything must be okay because you are firmly and safely in the grip of your mother, and your mother reassures you with a coo that everything is fine. Suddenly your fears quickly reverse, and you are utterly relieved. You interrupt your crying with a yip of recognition that chops the incipient long, loud bawl down into smaller ha-ha-has.

  As Morris envisioned it, this combination of mixed input sent a seemingly contradictory message: (1) There’s danger, but (2) not really; you are fine. This is the whiplash effect at its most basic. Maybe, he has speculated, laughter evolved from this combination of alarm and relief.11

  The thing about play is that it, too, is from an evolutionary standpoint, all about incongruous opposites. It seems to be about fun, but really it’s a survival technique, like laughter itself. Mock fighting, biting, tumbling, and chasing among young mammals provide a kind of dry run for the real battles that will follow.

  A big part of playing among primates involves tickling. Young chimps and gorillas spend a lot of time getting tickled—by their immediate family, or by one another. This has caused some researchers to propose that the building blocks of humor might be built upon the foundations of nature’s tickle reflex.12 Tickling, after all, exhibits many of the same dynamics that more sophisticated humor does. There is the element of surprise, for example, which may help explain why it’s impossible for us to tickle ourselves (your supplemental motor area won’t allow it). Tickling also juxtaposes danger and safety, pleasure and discomfort. It is a kind of mock attack. Neurological tests even indicate that the sensation of a tickle travels simultaneously along two separate sets of nerves fibers evolved to register completely opposite sensations: one for pleasure and one for pain. And finally, tickling is interpersonal, as all humor is. It takes at least two to tickle, just as it does (usually) to laugh.13 Or does it?

  Scientist Christine Harris was so fascinated by the question of the personal nature of tickling that she set up an unusual experiment designed to figure out if laughter, even ticklish laughter, requires two people. Her hope was that by figuring out the nature of ticklish laughter she might also get a handle on how every other kind of laughter works.

  But how do you test whether human contact is necessary to make a tickle ticklish when tickling is always done by humans? In other words, how do you take the human out of tickling? Harris and her team decided that creating a machine made for tickling might do the trick. If ticklish laughter had to involve at least one other real human, she figured, then no one would laugh if a machine tickled them.

  That, however, raised another problem: How do you create a machine that can tickle, and how do you make sure the person being tickled doesn’t know whether it is a machine or another human being doing the tickling? In the end, the researchers faked it. They created a mock tickling machine in their laboratory, complete with a robotic-looking hand, a vacuum-cleaner hose, and a nebulizer used in asthmatic therapy to provide some convincing sound effects. But the hand wasn’t actually robotic at all. It couldn’t even move.

  Subjects were told they would be tickled twice, once by a human experimenter and once by the machine. Next they were blindfolded, ostensibly to help them better concentrate on the tickling sensation. All of the tickling was actually done by a human hand that belonged to a second experimenter who was hiding beneath a cloth-draped table right next to the subject. The subject was told that he or she would be tickled once by the machine and once by a human, and the experimenter was careful to tickle the same way. If the subjects laughed when they thought they were being tickled by a human, but not when they thought they were being tickled by a machine, that would indicate tickling required human contact. It turns out it didn’t matter. Whether they thought it was a machine or a human tickle, the subjects laughed just as much. This was true even when the subjects were left in the room alone with the “machine,” and thought there were no humans anywhere nearby.

  But maybe the body somehow knows a human tickle when it feels it no matter what, and each of the subjects unconsciously recognized that the machine tickle was actually human. There’s no way to know. Whatever the case, it does seem that ticklish laughter and humorous laughter are cousins, even if we might not think so. Ticklish laughter, after all, doesn’t seem to involve any sort of wit or humor, but it does involve mixed messages and the same whiplashing opposites. Maybe in tickling we can glimpse a simpler, more primal form of humor, a foundation upon which the higher, cognitive experiences that make us laugh are built when we hear or see something funny. Maybe visual and verbal humor are a kind of symbolic tickling, except that rather than tickling our feet or stomach or neck, they tickle our minds.

  …

  There are other ways that tickling and play, and play and humor may be linked. Even though we resist tickling, we also only allow ourselves to be tickled by people we trust. Darwin pointed out that any child tickled by a total stranger would be unlikely to laugh. In fact, he predicted she would scream in terror. Tickling is intimate; it allows us to bond more closely with people we are already close to. The same happens when we laugh and joke with friends or even with strangers; we are connecting with them. This makes laughter a powerful form of nonverbal communication that inevitably draws us together. Considering how much we need one another as a species, there is enormous value in that.

  But how did laughter, and the feelings and emotions we experience when we laugh, come about? Why do we make the particular sounds we do when we laugh, and why do we contort our faces? And finally, why does laughter always surprise us? Put another way, how did laughter evolve?

  When chimps play, when they tumble and chase and tickle one another, they make a very precise panting sound, like rapid breathing. Some scientists call this laughter, but it is really nothing like the human variety. This doesn’t mean, however, that they aren’t connected. Robert Provine, a psychologist at the University of Maryland who has closely studied t
he origins of laughter, believes this panting evolved out of the way chimps breathe when they are worn out from play. He suspects that their efforts to catch their breath eventually developed into a kind of ritualized communication that also said “I’m having fun. I’m playing with you, not fighting.” If this is the case, then physical reaction to tickling may eventually have evolved into a symbolic reaction that we recognize today as human laughter.

  Still, the pants of chimps are not the same as a human laugh. Chimp pants, like all panting, is a sound made when air is inhaled and when it is exhaled. But human laughter is only exhaled. One explanation for this is that we have far more precise control of our vocal tracts when pushing air than when we pull it in. (Try talking as you inhale.) As a result, when we talk we inhale rapidly to set up the longer phrases we form when we exhale. This basically means that we have subordinated our breathing to our speaking. It may also explain why we don’t pant like tickled chimpanzees when someone gets off a witty remark. All of our laughs are exhaled (though we sometimes gasp for breath when we are laughing really hard).

  Provine theorizes that the reason we don’t pant like chimps is because we walk on two legs, not on all fours. He came to this conclusion after recording and combing through the sound structure of countless human laughs. He found that no matter whether we titter or guffaw, we generally chop laughs into outward blasts of air that last about a fifteenth of a second and then repeat those about every fifth of a second.14 But regardless of how often we do this, the sound is always exhaled. This is what gives human laughter its unique ha-ha-ha, staccato rhythm.