The biological magic of shared laughter

In a study conducted by the German paediatric surgeon Winfried Barthlen, clowns were asked to interact with hospitalised children awaiting surgery. Not surprisingly, these children showed less anxiety after a happy session with a clown. An analysis of their saliva samples showed elevated levels of oxytocin (see Frontiers in Pediatrics, 12, 1324283, 2024). 

Oxytocin is also called the bonding hormone because its levels are raised by social bonding and physical touch. Its presence increases the feeling of trust and signals that one is in a safe environment. Such neurochemical changes occur in moments of emotional well-being. For the anxious children, the clown was not just a distraction but the source of shared laughter; the clown’s presence facilitated a genuine social connection.

Other studies have shown that adrenaline and cortisol levels go down in people in whom laughter is induced, particularly when they are in the company of others with whom they share social bonds. Hormone levels are also lower when the study participants are induced to laugh together with strangers.

Both adrenaline and cortisol are stress hormones but they differ in how they act. Adrenaline is a rapid-response hormone: its presence raises blood pressure, heart rate, and blood sugar levels. The mild social stress that arises when meeting with unfamiliar faces is quickly deactivated when adrenaline is lowered: you relax. Cortisol acts slowly and the stress it induces lasts longer. When cortisol levels are lowered, the feelings of anxiety are also reduced.

By scanning groups of friends watching comedy clips together using positron emission tomography (PET), researchers in Finland showed in 2017 that endogenous opioids are released in the thalamus and other parts of the brain (Journal of Neuroscience, 37, p. 6125). Endogenous opioids act as analgesics and inhibit the sensation of pain, thus keeping you calm. In the context of social bonding, having fun together reduces stress and pain. It also serves as a reward system, the feeling of exhilaration encouraging you to spend more time in rewarding company.

Chimpanzees and other great apes also use laughter as a social lubricant. Sounding like a heavy pant, a chimpanzee’s laugh is evoked during play, such as when chasing or wrestling, or when they are tickled. Their social networks are nurtured by reciprocal grooming and play. Chimpanzees invest a considerable amount of time, up to two hours out of 12 waking hours, in social grooming. A chimpanzee’s “contact list” has about 80-100 acquaintances, with fewer than 20 being core allies.

People’s contact lists (on mobile phones) usually have between 300 and 600 names. Humans can remember the names and recognise the faces of about 1,500 individuals, acquaintances accumulated over time. It is thus evident that the expansion of human social networks has outpaced the time available for sustained one-to-one social bonding. One theory, popularised by the Oxford-based anthropologist Robin Dunbar, proposes that social laughter evolved in humans to permit shared emotional experiences among all the interacting members.

As the use of social media proliferates, we increasingly devote time to solo pursuits. Sure, you laugh and feel good when you see those forwarded kitten videos. But you laugh alone. When laughter is shared in a social setting, however, it becomes louder and more frequent as the group’s brain activity becomes synchronised. Interpersonal synchronicity lies at the heart of our social bonds. Maybe we should be spending more time in the company of our loved ones!

The article was written in collaboration with Sushil Chandani.