A Language Everyone Already Speaks
Babies laugh before they ever speak a word. Children born both blind and deaf still laugh. Laughter researcher Robert Provine put it simply: there are thousands of languages, but everyone speaks laughter in pretty much the same way. The study of humor and laughter even has its own name, gelotology.
Provine thinks laughing is partly in our genes. He studied the Giggle Twins, two sisters separated at birth and reunited 43 years later. Neither had ever met anyone who laughed as much as she did, even though both were raised by quiet, serious adoptive parents.
We are not the only ones who do it. Chimpanzees, gorillas and orangutans make laugh-like sounds when they wrestle, play chase or get tickled. Rats and dolphins make similar sounds too. The way tickled primates laugh is so alike that scientists suspect it all comes from a shared origin.
Inside a Laugh
A laugh is mostly a breathing event. It is made of rhythmic contractions of the diaphragm and other parts of the breathing system. Most laughs come in bursts, like ha-ha-ha or ho-ho-ho-ho, often broken up by loud gasps of air. Laughter also usually has a higher pitch than normal speech.
Some laughs are simply impossible. Your body cannot produce a laugh shaped like ha-ho-ha-ho. Changes tend to happen only at the first or last note, so ho-ha-ha or ha-ha-ho can happen. This fixed pattern is why we recognize a laugh even when everyone laughs a little differently. Your eyes also get wet as a reflex from the tear glands.
In the brain, laughter is tied to parts of the limbic system, including the hippocampus and the amygdala. Yet a 1984 medical journal noted there is no known single laugh center in the brain.
Why Laughs Spread
Laughter is often contagious. One person's laugh can set off laughter in others, which then feeds back into more laughing. It works as a signal that you belong to a group, showing acceptance and friendliness.
Researchers who study recorded conversations found something surprising. We tend to think of laughter as spontaneous and out of our control. In fact, people place their laughs very precisely within a conversation, and even time them against their partner's laughs. Laughter is not just a reaction to jokes. It often helps people get through awkward or serious moments and keep relationships smooth.
How much do we laugh? In a 1999 study, 80 people kept a daily laughter diary. On average they laughed 18 times a day. The range was huge, though. Some laughed as many as 89 times a day, and others did not laugh even once.
The Puzzle Inside Every Joke
One popular idea is called relief theory. Sigmund Freud summed it up as laughter releasing built-up tension. Philosopher John Morreall suggests human laughter may have started as a shared expression of relief once danger had passed.
A joke works like a small puzzle. It sets up something that does not fit, and your mind races to make sense of it. If you solve it and realize the surprise is harmless, you laugh. If you stay confused, you do not. As Mack Sennett put it, when the audience is confused, it does not laugh.
Carlo Bellieni boiled this down to three steps. First, something odd throws you off. Second, you work out the puzzle and the worry fades. Third, the laugh itself acts as an all-clear siren, telling everyone nearby that they are safe. Tickling is a strange exception: most people find it unpleasant, yet it often makes them laugh hard.
Can Laughter Really Heal?
In 2005, researchers at the University of Maryland reported that laughter widens the inner lining of blood vessels, the endothelium, and boosts blood flow. Laughter has also been shown to lower stress hormones such as cortisol. While you laugh, your brain releases endorphins, which can ease some physical pain. Laughter even raises the number of antibody-making cells.
Journalist Norman Cousins tested this on himself in 1964 while ill. Along with vitamin C, he watched comedy films, including the Marx Brothers. He wrote that ten minutes of genuine belly laughter gave him at least two hours of pain-free sleep. When the effect wore off, he switched the projector back on.
In a 2017 trial in Japan, laughter therapy with comedy, clowns and jokes improved quality of life for some cancer survivors, easing anxiety and stress. Still, one review warned there was not yet enough data to call laughter a proven cure, and more careful trials are needed.
