"Does photosynthesis occur in moonlight?" and "What’s the best way to treat insomnia?" BBC Click Radio presenter Gareth Mitchell answers life's big questions
"Call yourself an evolutionary biologist and you don't
even know what laughter's for – now that is funny!"
Here’s a date for your diary: Sunday 4th May, World Laughter Day. Described by its founder, Dr Madan Kataria, as “a very auspicious day for the whole planet”, it will be marked by groups of people the world over getting together for a good giggle.
What makes a joke funny?
Freud believed the best punch lines are those that provide an acceptable channel for pent-up sexual and aggressive impulses. The superiority theory says that we laugh hardest at jokes about people who make stupid mistakes. But the most popular is the incongruity theory. Take the joke: two fish in a tank. One turns to the other and says, “Do you know how to drive this thing?” The surprise brought about by the punch line makes us laugh.
Kataria, who introduced this annual event 10 years ago, says we need more laughter in our lives to combat the global rise of stress, loneliness and depression. But that’s daft isn’t it? Surely that strange yelping sound that we emit periodically can’t be the answer to such pressing problems.
If an alien were to land on our planet and take a stroll among a crowd of earthlings, it would notice that the low hum of speech was regularly interjected by much louder exhalations and that these outbreaths were chopped into ‘ha-ha’ fragments. It might wonder what purpose this strange habit served. If we ask ourselves what triggers a good chortle, the obvious answer is that it is a response to something we find funny. But one scientist, Robert Provine, who has spent nearly two decades studying laughter, says that humour has surprisingly little to do with it. Instead, it seems to lie at the root of such lofty questions as the perception of self and the evolution of speech, language and social behaviour.
Provine, a neuroscientist at the University of Maryland in the US and author of Laughter: A Scientific Investigation, realised early on in his research that you cannot capture real-life laughter in the lab because as soon as you place it under scrutiny, it vanishes. So, instead, he gathered his data by hanging around groups of people in public places, eavesdropping on their conversations, surreptitiously noting when they laughed.
Over the course of a year he collected 1200 laugh episodes – an episode being defined as the comment immediately preceding the laughter and the laughter itself – which he sorted by speaker (the person talking), audience (the person being addressed), gender and pre-laugh comment.
His analysis of this data revealed three important facts about laughter. Firstly, that it is all about relationships. Secondly, that it occurs during phrase breaks in speech. And thirdly, that it is not consciously controlled. “It’s a message we send to other people – it practically disappears when we’re by ourselves,” he says. “And it’s not a choice. Ask someone to laugh and they’ll either try to fake a laugh or say they can’t laugh on command.”
With these conclusions, Provine has challenged traditional models of laughter – which he believes put too much emphasis on humour – and also what people generally assume to be true about it. For example, we tend to think that we know why we have just laughed. “You might say, ‘I laughed because I was embarrassed’, or ‘I laughed because it was funny’,” says Provine, “but these are all posthoc rationalisations. They’re not the reason that you laughed.”
Perhaps most surprising of all is Provine’s finding that only 15-20 per cent of everyday comments preceding laughter are remotely humorous. “Laughter usually follows comments like ‘I’ve got to go now’, ‘Here’s John’, ‘Where have you been?’,” he says. “Simply observe it in your own life and you’ll see that most laughter is like the laugh track of the world’s worst sitcom.”
The fact that we don’t have conscious control over when we laugh suggests that it must be deeply embedded in our nature, programmed by our genes rather than learned from our environment. Indeed, studies of the play behaviour of great apes suggest that having a good giggle has been around a lot longer than we have.
Chimpanzees laugh while they are having play fights although the sound is quite different to that made by humans due to their different vocal apparatus. Instead of chopping a single exhalation into the ‘ha-ha’ sound that characterises our laughter, chimps laughter sounds like panting. A recent study of orangutans reveals a deeper similarity with humans. A team of researchers watched the play behaviour of 25 individuals aged between two and 12 at four primate centres around the world.
Where inside your head does laughter come from?
There isn’t one brain centre for laughter as such. Instead it involves a network of different areas. As it is an ancient behaviour that evolved millions of years ago, it is thought that the physical act of laughter is generated by a mechanism in the brainstem that modifies respiration to enable the ‘ha-ha’ sounds to be produced. Humour, or conversational play, involves areas of the brain in the more recently-evolved frontal lobe. In brain-imaging studies, different sorts of jokes light up different parts of the cortex.
“In particular we analysed the facial expressions that they produce during social play,” says Dr Marina Davila-Ross of the University of Portsmouth. “It’s a relaxed expression where they open their mouth and show the upper row of teeth. It is very similar to the human expression of laughter.”
The team discovered that when one orangutan displayed this expression, its playmate would often produce the same expression less than half a second later. The speed with which this mimicry occurred suggested that the expressions were involuntary – in other words the laughter was contagious. “In humans, mimicking is a mechanism that enables us to understand our social partner better, and this helps us to cooperate and form social bonds. It is clear now that it evolved prior to humankind,” says Davila-Ross.
Prof Richard Wiseman, psychologist at the University of Hertfordshire and organiser of LaughLab (an internet-based experiment into the psychology of humour that involved over 350,000 people from 70 countries), agrees that laughter is contagious because it enables us to bond more strongly with each other. “We are social animals, and so it is a very helpful communication tool if we can feel what those around us are feeling. Laughter is contagious because it helps us communicate and empathise with others,” he says.
The fact that we share laughter with great apes suggests that it emerged in our ancestors sometime before the split with chimpanzees six million years ago. But it may have evolved even earlier than that. Research conducted at Bowling Green State University in Ohio, US, found that even rats produce chirps comparable to laughter when playing or when tickled, and the common ancestor of rats and humans lived 75 million years ago.
It is hard to say for sure whether rat ‘laughter’ shares the same evolutionary roots as human laughter, but the fact that it is triggered by tickling suggests a strong link because, as Provine puts it, “tickle is the most ancient and reliable stimulus of laughter”. One of the earliest ways in which a parent and child laugh and play together is through tickling.
For chimpanzees it is just as common and remains an important social interaction throughout their lives. Chimpanzees who have been taught sign language regularly discuss tickling amongst themselves. Laughter and tickling go together – the former seemingly a reflex reaction to the latter, comparable to the reflex reaction you experience when a hammer strikes your knee.
Studies of tickle (the preferred scientific term), although thin on the ground, should therefore be able to tell us a lot more about laughter. For example, we all know that we cannot make ourselves laugh through tickle. But could a machine tickle us?
One team of researchers at the University of California at San Diego built a mechanical tickling machine, complete with robotic hand and wiggling fingers, to look at this very question. They discovered that their subjects laughed just as much in response to the machine as to the experimenter. This tells us that a successful tickle doesn’t depend on another person, but merely on another entity, something that’s not you.
Provine thinks that this finding goes to the heart of an even more profound question than that of laughter. “By considering this not-youness, we discover the criteria for self,” he explains. “We’re getting to grips with a neurological mechanism for what’s us and what’s other. A tickle reveals the neurological mechanism for sociality.”
Discovering that laughter can be used as a tool to explore other aspects of our behaviour has, for Provine, been one of the most rewarding aspects of his research. Perhaps his most important insight concerns the evolution of speech, a critical event in our history that occurred sometime after we split from chimpanzees.
Provine believes that the evolution of speech and bipedal locomotion are causally related. He came to this conclusion after analysing the difference between chimp and human laughter. “It occurred to me that, basically, the human ‘ha-ha’ came about as a result of the evolution of breath control that chimps lack,” he explains. We hold our breath to lift heavy objects and quadrupedal animals must do the same when moving in order to support their body when their four limbs hit the ground. When our ancestors stood up on two feet, the thorax was freed of these mechanical demands, making it possible for speech to evolve.
“People talk about bipedality being important for carrying infants or manipulating objects in front of the body but something that hadn’t been considered was that walking upright on two legs was necessary for the evolution of speech,” concludes Provine.
By breaking away from traditional models of laughter as a mechanism simply linked to humour, and discovering its links to deep elements of human nature such as speech and sociality, Provine has reinforced just how ancient laughter is. It has been around for as long as rough-and-tumble play, an activity that you see in mammals, from rats and squirrels to chimpanzees and humans, and has most likely evolved from the laboured breathing or panting that accompanies such play.
Ultimately, it is a response to feelings of social connectedness – you don’t see any sign of it in reptiles simply because they are not social in the way that mammals are. Like many things that feel good – eating or sex, to name a couple – it is a behaviour that goes to the core of who we are as animals. So, yes, we probably should do it more to increase our sense of well-being. Maybe World Laughter Day isn’t such a daft idea after all.
Emma Bayley is Focus’s contributing editor
Robert Provine, professor of psychology and neuroscience at the University of Maryland, US
Why do we laugh?
Laughter is about relationships. We laugh much more often when we’re around other people than when we’re alone. Media is considered to be a social stimulus, so when you laugh watching a TV programme you’re laughing at the people on the box. But when you’re by yourself, not reading, not watching TV, laughter is less frequent.
Why do the urges to laugh and cry sometimes come at the same time?
Laughter and crying are closely related neurologically and evolutionarily. They both evolved as signals to change the behaviour of other people. We’re pretty good at inhibiting them but it’s hard to produce either on command. They also occur together pathologically – one of the most common symptoms of psychopathology and neuropathology is inappropriate laughter and crying. An important difference between laughter and crying, however, is that laughter is highly social, whereas crying is not. A solitary person can cry but rarely laughs.
How does the laughter of men and women differ?
Men talking to each other laugh a lot. Women talking together laugh a lot. The striking thing is that when men and women talk together, women usually laugh more than men. Men are the best laugh-getters. A number of different labs have found this in different countries around the world. Also, when people talk about class clowns, they’re almost always male.
Why do women laugh more when they’re talking to men?
Women laugh most at men that they find interesting or attractive. And men like women who laugh in their presence. This is reflected in personal ad columns. Women tend to request a good sense of humour, and men tend to advertise a good sense of humour. But laughter is not planned – it’s an honest signal and it’s hard to fake. A woman doesn’t think I want this man to like me so I’m going to laugh a lot. It just happens. If you learn how to read laughter, you can get insights into what people really think about each other.
How does humour relate to laughter?
Humour involves strong linguistic and cognitive components that are superimposed on the more ancient laughter structure. Probably the most ancient joke and the only one you can tell to both babies and chimpanzees is a feigned tickle where you act like you’re going to tickle and say things like, “I’m going to get you”, and then don’t tickle. Humour is a more cognitive level of play that evolved more recently. If you look at rough-and-tumble play, that’s where it came from. Human adults don’t typically run around chasing and tickling each other. They have conversational play, which is similar in that it still has this give-and-take in it.
The health benefits of having a good chortle
It has long been recognised that laughter and humour are good for you. Laughter makes us feel good – that’s why we pay comedians. After a really good belly laugh, when asked how they feel, most people say: “I feel a lot more relaxed.” A number of studies have emerged in recent years that show specific ways in which laughter has remarkably beneficial effects on our health.
Just the expectation of laughter boosts production of beta-endorphins, the body’s natural painkiller, by 27 per cent
A good laugh produces an increase in heart rate that is equivalent to 10 minutes on a rowing machine or 15 minutes on an exercise bike
Laughter lowers stress hormones, such as cortisol, produced by the adrenal glands, which sit on top of the kidneys
Laughter improves breast milk’s health effect – breast-fed babies with eczema experienced milder symptoms if their mothers laughed hours before feeding them
Laughter is linked to the healthy function of blood vessels. It causes the inner lining of blood vessels – the endothelium – to dilate or expand in order to increase blood flow
Laughter also increases immune-system antibodies, such as immunoglobulin A, which helps to fight upper respiratory disease
Hang out with more people
The more people you are with, the more laughter there will be around you and the more likely you are to join in with a chuckle or two.
Increase interpersonal contact
Increasing face-to-face and eye-to-eye contact with your fellow group members increases the chance that you’ll have a laugh.
Create a casual atmosphere
Worry and anxiety kill laughter, so light a few candles, put on some music and settle down with some friends for a good giggle.
Be ready to laugh
You may not be able to produce a convincing chortle voluntarily, but you can lower your laughter threshold simply by expecting to laugh more.
It’s the most ancient laugh stimulus. But be warned, the pleasure of tickling depends on who’s doing it – best not to tickle strangers
Call a professional
Obvious but effective – expose yourself to humorous entertainment such as TV shows or live comedy. Comedians make a living making you laugh.