Sitting in the audience at a stand-up show; watching a comedy at the movies; at the office party when your boss breaks out their best knock-knock joke: these are all places where laughter is both encouraged and expected. During a quiet moment in church? Not so much. But wherever you are, if you hear someone else laughing, it’s likely you’ll get the urge to giggle too – however inappropriate that may be! Should we all just be able to control ourselves better, or is laughter really contagious?
The answer, in short, is yes.

“All emotions are contagious”
“Is laughter contagious? Well, actually, all emotions are contagious,” Dr Sandi Mann, chartered member of the British Psychological Society, told IFLScience. “We are designed to pick up other people’s emotions.”

It’s part of our evolution, and it’s something we share with other mammals. It’s been well established that apes – our closest relatives – laugh in a remarkably humanlike way. If you’re ever close enough to a bonobo to try tickling it (not something we’d necessarily recommend), you’ll find out.

Recent research even found that apes may have a sense of humor and love to tease each other. A 2021 review concluded that 65 different animal species show evidence of “play vocalizations” that mimic humans laughing when we’re having fun, mostly mammals but a few birds as well. 

In fact, laughter is such a fundamental part of what it means to be human that it transcends language and culture – there’s not a single community of people on Earth that we know of who don’t laugh. 

Why laughter is good for us
Part of the reason why a fit of the giggles spreads so easily, Dr Mann told us, is that shared emotions are integral to social bonding. A 2022 paper from University of Oxford Emeritus Professor of Evolutionary Psychology Robin Dunbar explored this further. 

“I suggest that, when hominins needed to increase the size of their groups beyond the limit that could be bonded by grooming, they co-opted laughter […] as a form of chorusing to fill the gap,” Dunbar wrote. 

Grooming – a social behavior we particularly associate with monkeys and apes, but which is seen throughout the animal world – boosts the production of endorphins in the brain. These chemical messengers relieve pain and generally make us feel good. Dunbar detailed some evidence that laughter has a similar effect, with the added benefit of being less intimate and time-consuming than grooming. Hence, humans laugh together all the time, but we’re rarely seen picking lice out of each other’s hair these days. 

A hit of endorphins also helps us de-stress. When a group of people are sharing a tense situation, Dr Mann told IFLScience, humor can help to alleviate that as well as strengthen the bond between them: “Sometimes we just need to smile, laugh, have fun to relieve the stress.”