May 2 is World Laughter Day! Apart from simply feeling good, laughter has internal health benefits and plays a foundational role in how we form relationships. Laughter is a natural response to something funny right? Wrong! Laughter is actually quite unrelated to jokes and humor. Remarkably, laughing behaviors are consistent across cultures, spanning all of humanity, while humor tends to vary widely between cultures and even cultural subsets.

Why So Serious?

Human laughter is currently thought to be an evolvement of behaviors seen in the animal kingdom such as how chimps and other primates make a panting sound when tickled or when playfully roughhousing, and how dogs strongly exhale with a “sneezing” or “huffing” sound to indicate playfulness. These nonverbal cues are meant to convey to others that the animal is friendly and nonthreatening. Similarly, humans use laughter to elicit positive reactions from other people and to communicate to them that we mean them no harm. Compared to other species, humans rely on cooperative behavior with non-family members to a much larger extent, but are also inherently competitive. So, we had to evolve a more definitive way to show others we feel positively towards them and to forge connections.

Indeed, the degree of relationship between people is reliably identifiable by their laughter. In a cross-cultural study participants listened to sound clips of two people laughing together and were able to correctly determine if the two people had just met or were long-time friends. Not only does this say something about the people laughing, but as for the people listening this study highlighted the high-degree of sensitivity to laughter we posses.

Emphasizing the role of laughter as a social cue unrelated to humor, people are 30% more likely to laugh when in a group. In one study of children watching a cartoon, the kids were eight times more likely to laugh when watching with a friend, even though they reported the same level of amusement with or without a companion. Rather than laugh, people are far more likely to comment to themselves or smile when alone.

Are You Kidding Me?

Many ideas we have about laughter are incorrect. We think of laughter as a response to a joke or witty comment, but in a study of thousands of examples of laughter, the speakers in a conversation were found to be 46 percent more likely to laugh than the listeners. This shows that laughter is an signal of desire to connect. These cases show that humans often use laughter as punctuation, inserting it into specific places in the vocal stream such as at the end of a sentence or phrase, but not in the middle of a phrase. This behavior is such an inherently human trait that congenitally deaf people laugh at the same points in signing conversations that hearing people do in speaking conversations.

Laughing Matters

In our blog post on hormones and happiness, we noted that laughter can increase endorphin production leading to increased feelings of happiness, decreased stress and an immune system boost with an increase in natural killer cell activity. In the words of famed comedian Groucho Marx, “A clown is like an aspirin, only he works twice as fast.” While the current research isn’t yet strong enough to support actual laughter prescriptions, there are no negative side effects of laughing. So go ahead and chuckle, giggle and guffaw all you want!