What's Funny? The Science of Laughter

As one wanders down the hallways of Stuyvesant High School, a prominent sound tends to fill the air: laughter. Even when drowning in piles of schoolwork, many of us still find time out of our day to laugh, a seemingly simple gesture that occurs as a reaction to something funny. However, a simple “hahaha” or “hohoho” may be much more complex than scientists  initially thought, as many still ponder the true reason why humans laugh so much in our day-to-day lives.

Laughter is the psychological and physical reaction to humor. Humor itself does not have a clear-cut definition, but it typically encompasses the ability of something to be comical or amusing. Although humor can be vague or difficult to understand, most humorous things that lead to laughter have something in common—the element of surprise. For example, many people tend to laugh in serious situations because it isn’t something you would expect in everyday conversation. Jokes comedians make typically have an unexpected “catch” that makes them funny—a moment that breaks the brain’s pattern recognition. Your brain is wired to recognize patterns, which a job taken on by the neocortex, the outermost layer of the brain. When those patterns are broken through, your brain notices a discrepancy and rewards itself as emotional activity in the brainstem spikes. This leads to a rise in natural painkillers and stress relievers including dopamine, oxytocin, and endorphins, which explains a “feel-good” feeling associated with laughing at something funny.

To reach this point, the brain perceives a funny stimulus and triggers the process of producing a laugh. Many different parts of the brain are used to interpret humor. For example, the frontal lobe works to understand social and emotional situations while the cerebral cortex analyzes the structure of the humor, thus allowing for humor to be logically processed. This information is relayed to the rest of the brain to produce laughter. Laughter itself occurs through the contraction of a combination of facial muscles as well as the behavior of the respiratory system's epiglottis—a flap that covers the larynx, or voice box and controls air flow—in certain ways such that air intake into your lungs becomes sporadic. This produces the resounding laughter that everyone knows and loves.

However, the true reason behind why laughter exists today lies in evolution. For example, the rat and chimpanzee both exhibit laughter, along with many other species. Laughter is often seen in herding animals as a way of signaling that a situation is safe as well as assessing other’s intentions to deem them as trustworthy. After all, being able to trust a group of animals rather than working alone in herding groups is almost always favored for survival. Parts of the brain, such as the frontal lobe and neocortex, are also more active during laughter, signaling that the brain has developed patterns to recognize laughter as an evolutionary advantage. This pattern recognition reflects in the human tendency to naturally mimic others, making laughter actually contagious along with inciting feelings of joy and relief. However, humans are the only species to exhibit two different types of laughter, giving us an insight into the true reason why humans laugh so much in our daily lives.

These two types of laughter are known as Duchenne and non-Duchenne laughter. These names arise from 19th-century scientist Guillaume Duchenne, who mapped out many of the facial muscles involved in laughter. Duchenne laughter is more spontaneous and emotional and typically seen as a response to something genuinely funny and joy-inducing. Studies show Duchenne laughter triggers parts of the brainstem and limbic system, which are the areas of the brain that are primarily responsible for emotional activity. For example, a study conducted by D. Keltner and G. A. Bonanno shows how Duchenne laughter affects our emotions, leading to better anger management, social relations, and positive engagement with strangers. Duchenne laughter is usually associated with smiling with one’s eyes and suggests a more genuine connection between people. 

On the other hand, non-Duchenne laughter is only present in humans. Scientists believe this to be associated with the development of social situations in our lives, requiring a form of “fake” laughter to connect, show respect, and seem likable to others in conversation. This laughter is seen as a “polite smile” and is generally more controlled and done on purpose. It seeks to imitate spontaneous laughter but ultimately fails to trigger the same psychological effect in others as Duchenne laughter does.

Although the evolutionary theory for laughter and its importance in social interaction is the most accepted reason why laughter exists in our lives, some other theories may also help us interpret laughter and its purpose. The Relief Theory of Humor is an interpretation of laughter as a means of stabilizing our emotions and relieving ourselves of pent-up nervous energy. The Superiority Theory is another interpretation that presents how humans feel good about not being in a worse situation than they see someone else in, causing them to laugh at the person in the worse situation. A common example of this is when you see someone get injured or when someone else is crying, sometimes resulting in an urge for you to laugh even though there is no rational reason to do so.

As we navigate through our stressful lives, let’s not forget the power of laughter, providing us with a constant reminder that no matter how different we can be, everyone can always bond over a simple “hahaha!” every now and then.