Humour and the evolution of laughter
For centuries, people too boring to tell jokes have been trying to explain why they are funny.
Thomas Hobbes thought humour was about feeling superior to others. If he’s right, he won’t be laughing much, since his theory sucks.
Francis Hutcheson thought humour was about realizing that something is incongruous. Like long acrylic nails on a police dog, or a funeral where the eulogizer breaks into speed-yodeling. Or a sentence where you imply that Thomas Hobbes’ theory sucks if it is right – and that’s the reason his dusty corpse won’t be laughing. At first your brain tries to interpret things seriously, but a moment later you realize that’s absurd!
Herbert Spencer and Sigmund Freud thought that humour was due to relief, or the discharge of repressed “psychic energy” which builds up due to false expectations.
Much more recently, McGraw and Warren suggest that humour is the result of a violation that is also taken to be benign.
If we leave out the theory of superiority – the inferior theory, here – the punchline these theories share is that a joke works because of how we deal with surprise. Our expectations are violated, but the violation is overcome / the stakes are lowered.
Incongruity theory is about frame-breaking. You start with the assumption that things must be normal, and then you see the leprechaun grasp the stripper pole.
Relief theory suggests that false expectations are the source of internal pressure, which is released by a folksy pressure valve – as if the brain ran on some law of conservation-of-emotion.
Benign violation theory makes it a bit clearer that people laugh at different things. Some people take a violation more seriously than others. What counts as “benign” depends on context.
None of them are clear about where laughter comes from, though.
Laughter is classically treated as just the obvious symptom of humour – you could refer to either laughter or humour and be pointing at the same thing: Hutcheson’s book on humour is called Thoughts on Laughter, and Spencer’s is The Physiology of Laughter. But laughter and humour are not the same. Laughter is a motor action; humour is a mental move. Most of us have laughed without joy before, or suppressed laughter when it would be inappropriate.
One theory of laughter is that it is a play signal. Play is important because it allows us to get close to being in a dangerous situation without actually being in much danger. It’s a low-stakes simulation where we practice for the higher-stakes future.1 Since we want it to be a good simulation – and since sometimes there could be real violence between the same people who played together – it’s important to make it clear what’s play, and what isn’t. Laughter says we’re playing right now; it isn’t that serious.
Other mammal species play, and have play vocalizations that are similar to human laughter. Play in its oldest and stupidest form is about physical aggression, but the same vocalizations could be adapted for more subtle games, like wordplay. So we end up laughing to indicate “this isn’t serious disrespect, it’s just a stand-up comedian simulating disrespect, ahaha we’re all just playing right now”. (Some audience members will not find the violation so benign.)
But laughter-as-play-signal doesn’t explain how laughter evolved in the specific form it did. Why the rapid contractions of the diaphragm? Why not just make some other noise or movement for “playing”? Maybe because laughter is particularly simple and legible even when it would be difficult to make other noises? I’m not satisfied.
There’s an ancient coupling between breathing, brain activity, and emotions. When you slow down and hold your breath for a moment, your body becomes more still. Predators are less likely to notice you, and you are more likely to notice them. A moment later you may be more confident in your surroundings, enough to breathe harder, and move around. There’s a rhythm between moving-and-breathing, and stopping-and-slowing – change your surroundings, then process the consequences, then repeat.
Even a solitary animal has these rhythms. And since they use them anyway, they’re ready to be adapted for social purposes: a single exaggerated exhalation could serve as a signal to nearby friends that this is a low-threat moment – so let’s move. Later, a single exhalation is adapted into a series of repeated exhalations which signal something similar, but over a longer period.
That’s my favourite hypothesis about the embodied origin of laughter: it’s an evolved caricature of exhalation, which was available to be caricatured because it was already coupled to fear/appraisal/relief dynamics at a low level.