Ever Wonder Why We Laugh?

A mosaic of people laughing

A few nights ago, while laying in bed going down another YouTube rabbit hole, I was stricken by a fit of laughter. There I lay, chattering “hehehe” into the darkness, rocking the bed with every spasmodic exhale.

Looking in on myself from the outside, it all seemed very strange. Here I was, a highly civilized human being. But show me a video of a kitten startled by a sneeze, and I immediately devolve back into an overexcited monkey.

It made me wonder: what purpose does laughter actually serve? And why is it so infectious? 


Laughter is a primitive instinct. Babies begin to laugh around 3 months old, long before they can even talk. 

While laughter is often an automatic reaction, we can also invoke a polite chuckle when the situation calls for it. The experience is notably different. In fact, voluntary and involuntary laughter are even controlled by different parts of the brain.

Laughter is a language that runs deeper than words.  Despite our verbal prowess, saying “That’s funny” after a joke means nothing. But hearing a laugh track over a corny sitcom joke can actually convince us that it’s funny.

Some laugh triggers are nearly universal, such as being tickled or surprised. Jokes tend to be more personal. Some people chuckle at puns, others groan. Children and adults alike both lose their minds over broken social taboos, like dirty jokes and toilet talk. The biggest laughs come from humor we strongly relate to, such as an inside joke between friends or a bit that’s “funny because it’s true”.

Humans also have a tendency to laugh at misfortune, such as the case with slapstick comedy. The Germans actually have a word for this ironic source of humor: Schadenfreude. 

Even though laughter seems to be an unconscious reaction, there’s no single stimulus that triggers the brain to invoke a laugh. In fact, depending on your mood, the same joke you laughed at one day could fall flat the next. If your laugh reaction were entirely about the joke, you wouldn’t be able to help yourself. 

The fact of the matter is, laughter is less about your own reaction, and more about how others react to you.


In nature, many animals have instinctive communicative calls that are necessary for survival. Warning cries broadcast the presence of predators, or alert fellow clan members to a food source. Calls may also be used socially, to attract mates or establish dominance. 

Despite our complex vocabulary, humans retain some of these communicative instincts.  We yell when we are startled, and cry to signal when we are hurt. Clearly, our brains know that when in danger, it’s best to skip higher language processing and get straight to the point.  

When humans laugh, we are communicating relationships. And as a species that entirely depends on a complex social hierarchy, communicating relationships is about as vital a reaction as drawing our hands back from a hot stove.

When approached by a stranger, our instincts read body language and facial cues to determine whether they are a friend or foe. Laughter is a signal that puts us at ease and signals a playful intent. It tells us that this person means to share pleasure with us. 

When we laugh with friends, we are communicating that we relate to them, just like a cat purrs to indicate it enjoys your company. Our brains don’t even care if we are alone, just watching TV or reading a book. In our minds, we’re still relating to another human being – whether the character or the creator. And as socially dependent creatures, our brains never miss a chance to  broadcast “I’m with you!”


Humans laugh all the time, and not always as a reaction to humor. We laugh as part of everyday conversation. A laugh can be an ironic answer to a question, such as “How’d you do on that test?” We punctuate our text messages with LOL just to make them seem more personal, even when talking about serious things. Here again, laughter says, “I’m your friend” more than it says “This is funny.”

We are also more likely to laugh when we are in a group. One study on children watching cartoons showed that they were 8 times more likely to laugh when watching with other kids than when watching alone. In a group, the instinct to communicate “I’m experiencing pleasure with you!” was much stronger. 

As a form of communication, laughter also becomes more intense with deeper social connection. One study compared the sounds of strangers laughing together with friends laughing together. Participants were easily able to tell the difference between the two. Other animals with complex social hierarchies, such as monkeys and elephants, share this ability to module the sound of their vocal calls to establish levels of relationship.

This also suggests we humans can easily discern between fake and genuine laughter, a necessary advantage against foes who may try to get our guard down under false pretenses.


As much as humans use laughter to signal positive social relationships, it can also be used to strengthen those relationships against outsiders. 

When a group of schoolchildren bond together to tease another classmate, they are signaling their solidarity with each other, and casting the victim further from their group. 

When you’re being laughed at, you can tell the difference. The sound of the laughter may seem the same, but the intent is clearly different. Instead of saying, “I’m your ally” the message is quite the opposite. “We’re all allies against you!” 

This could also be the basis for why we laugh at slapstick and misfortune. When we observe weakness, it reminds us that our own sense of self-superiority is not guaranteed. As a result, we feel a need to seek reassurance that we are part of a stronger, superior group. No, we are not the hapless clown that just got a pie to the face. We are the “others” – watching and laughing together. 


As a social signal, laughter could have taken many forms. But the form it did take of rhythmically exhaling creates a physical reaction in our bodies that feels good, and enhances the feeling of pleasure.

Forced exhalation clears the lungs and leads us to draw in a deeper breath, giving our blood a boost of oxygen that stimulates our muscles and brain. As our muscles tense up and relax, our circulation is stimulated and pent up toxins are released. Our tear ducts are squeezed like a bellows, forcing us into tears of laughter.

Laughter causes our heart rate and blood pressure to increase and then decrease, signaling our body to release anti-stress chemicals, feel-good endorphins, and even neuropeptides which boost our immune system. As we cool down, the brain releases inhibitory signals to dial back our over-excited nervous system. As a result, we feel a general sense of relaxation and pleasure wash over us.

Because laughter feels good, it strengthens the bonds of the relationship between the people experiencing it together. It encourages us to do it more often, and to seek out other people who can make us laugh, thus fulfilling our need for human connection. Truly, in the words of Pablo Neruda, “Laughter is the language of the soul.”

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