"Everyone laughs. And most people, most of the time, would prefer to have more of it than less. So it’s no surprise we like to be around people who can get us laughing. The fact that everyone wants to laugh suggests that laughing did something big in our evolutionary history. But what? Robin Dunbar, who heads the Social and Evolutionary Neuroscience Research Group in the Department of Experimental Psychology at the University of Oxford, has an intriguing proposal: Laughter is what allowed human social bonding to scale with the increasing size of our groups beyond what conventional forms of social grooming, between closely tied individuals, could possibly provide. When primates groom one another, combing through fur to remove entangled bits and pieces of vegetation and bugs, the hand movements trigger the brain’s endorphin system, which, according to Dunbar, underpins the creation of friendships in primates and possibly other mammals.

"As our societies grew, we needed something that could work more efficiently in holding us together." - Brian Gallagher