Finally, Bachorowski identified where laughs fall in acoustic space compared to consonants and vowels. Here a remarkable discovery: Laughs occupy a part of acoustic space that is different from vowel sounds like “ahhh” and “eee.” We may describe laughs in the written word as “ha, ha, ha” or “hee, hee, hee,” but in fact the acoustic structure of laughter is distinct from that of the vowels we use to represent this mysterious category of behavior. Certain regions of the human vocal apparatus produce the vowels and consonants that make up human speech, in which so much of human social life transpires. But there is another register of the human vocal apparatus, another form of output—laughter—with different origins and functions than human speech.
In light of Bachorowski’s discoveries, it is now assumed that laughter preceded language in human evolution, emerging in early protohuman form some four million years ago. This is significantly earlier than when humans started to put together vowels and consonants into phonemes, and those phonemes into words and sentences. Recent neuroscientific data on laughter, summarized by Willibald Ruch, one of the leading laughter scientists, yields a similar conclusion about the early appearance of human laughter in evolution. Ruch has synthesized numerous brain studies of laughter. Some focused on the brain correlates of pathological laughter. For example, people who suffer from a syndrome known as pseudobulbar affect will abruptly break into uncontrollable laughter in response to inappropriate stimuli—the tilt of a head, the movement of a hand, a trivial comment in a conversation. In other studies, laughter was observed following electrical stimulation to specific regions of the brain. When people laugh, subcortical, limbic regions of the brain and brain stem—most notably a region known as the pons, which is involved in sleep and breathing—are activated. These regions are much older evolutionarily than the cortical regions involved in language, suggesting that the deeper meaning of laughter is intertwined with breathing.
WHAT’S SO FUNNY ABOUT LAUGHTER
Laughter, then, is social and contagious. It empties the air deep in the cavities of our lungs, allowing heart rate and blood pressure to drop, the muscles of fight/flight exertion to go limp, and our psyche to fall into a calm state. These laughter facts fit nicely with the most enduring notion about the meaning of laughter, that it is the behavioral output of the experience of humor. Humor is as difficult to deconstruct as laughter, but there is consensus about the canonical structure of humorous acts: they involve some juxtaposition of contradictory propositions that produces a state of tension and ambiguity. The resolution of that contradiction then arrives in the form of a conceptual insight or punchline, the contradiction is resolved, and we laugh.
This hypothesis, that laughter serves to reduce tension, ran into some uncharitable data gathered by Robert Provine. Rather than restrict himself to the sterile confines of the laboratory, or rely on abstract, armchair conceptual analysis, Provine turned his astute ear to the laughter that occurs in the real world. He had three undergraduate assistants surreptitiously record bursts of laughter in malls, in friendly conversations on street corners, in the cafeteria banter of college students. This small band of laugh collectors recorded over 1,200 laughs in all. Provine transcribed these episodes into laughter narratives and then dissected what people were talking about just prior to laughter.
Humor often did precede laughter. Who wouldn’t have laughed or at least chuckled with head tilted back, closed eyes, and collapsed torso and shoulders after hearing the following statements?
She’s working on a PhD in horizontal folk dancing.
You just farted!
Poor boy looks just like his father.
When they asked John, he said that he wanted to grow up to be a bird.
Do you date within your species?
Was that before or after I took off my clothes?
Is that considered clothing or shelter?
Humor-oriented utterances, however, represented only 10 to 20 percent of prelaugh statements. Importantly, Provine found that laughter followed all sorts of utterances. Over 80 percent of the laughs did not occur in response to humor. Consider some of the following utterances that produced laughter.
I see your point.
I hope we all do well.
We can handle this.
I told you so!
Are you sure?
Why are you telling me this?
What is that supposed to mean?!
Not exactly knee-slapping fare ready for The Daily Show, Saturday Night Live, Robin Williams, the class clown, or the town wit. If these elicitors of laughter were just exceptions to the rule, we could readily discount them. But conversational events unrelated to humor were the rule and not the exception, and beg for more precise theorizing about laughter.
THE COOPERATION SWITCH
What, then, is the conceptual unifier of the cackles, guffaws, hisses, chortles, snorts, and melodious songs that we hear every day, or at least on the days that are more pleasing to the soul? We have seen that the time-honored thesis—humor—does not suffice. It fails to explain many, even the vast majority, of laughs that occur in our daily living. For Bachorowski and her colleague Michael Owren, the answer is cooperation. In an insightful analysis, Bachorowski and Owren argue that laughter builds cooperative bonds vital to group living. It does so through two mechanisms.
The first is contagion: We routinely laugh, and experience exhilaration and levity, at the sound of another’s laugh. The contagious power of laughter motivated the introduction of laugh tracks on TV, a history that Provine details in Laughter. Recent neuroscience evidence suggests that when we hear others laugh, mirror neurons represent that expressive behavior and quickly activate action tendencies and experiences that simulate the original laugh in the listener’s brain. Specifically, laughter triggers activation in a region of the motor cortex in the listener, the supplementary motor area (SMA). Bundles of neurons leaving the SMA go to the insula and the amygdala, thus triggering the experience of mirth and amusement in the perceiver of the laugh. When we hear others laugh, this system of mirror neurons acts as if the listener is laughing.
Laughter builds cooperative bonds through a second mechanism, Bachorowski and Owren propose: Laughter rewards mutually beneficial exchanges—successful collaborations at work, in the kitchen, in child rearing, with friends. Laughter signals appreciation and shared understanding. Laughter evokes pleasure. Given that each individual has a signature laugh, produced by the particulars of the vocal apparatus, laughs become unique rewards of cooperative exchange, building trust between individuals.