In a study published in the Proceedings of the Royal Society B, researchers at the University of Oxford found that laughing spurs a rush of endorphins, in much the same way as exercise, sexual activity and eating spicy food.
As well as generating mild euphoria, the endorphins dull pain. But we're not talking about a giggle here – the research team found that only a proper guffaw will do the job.
In conducting their study, the scientists first tested the pain thresholds of volunteers, before splitting them into two groups, reports the BBC.
Group 1 was shown 15 minutes of comedy videos, while the other was shown material deemed to be boring, such as “golfing programs”.
During subsequent pain tests, the scientists discovered that the people who had enjoyed a belly laugh were able to withstand up to 10 percent more pain than they had beforehand.
Professor Robin Dunbar of Oxford University, who led the research, told the BBC that the “emptying of the lungs” when laughing is what causes the release of endorphins.
It's exactly what happens when we say 'I laughed until it hurt'. It seems to be extremely painful and it's that pain that produces the endorphin effect.
Surprisingly, the scientists also discovered that the group made to endure the woeful golfing videos was less able to withstand pain afterwards.
In their findings, the research team said the ability to belly laugh was unique to early humans, reported Live Science.
Professor Dunbar said very little research has been done into exactly why humans laugh, and what role it plays in society.
We think that it is the bonding effects of the endorphin rush that explain why laughter plays such an important role in our social lives.
Our ancestors' ability to laugh, apparently, enabled them to form larger tribal groupings than the ape species that lived alongside them.
Seems evolution is a funny thing.