New Scientist - Interview

Humans don't have a monopoly on laughter, says Silvia Cardoso. A behavioural biologist at the State University of Campinas, Brazil, she says it's a primitive reflex common to most animals: even rats laugh. She tells Sophie Petit-Zeman that too little laughter could have serious consequences for our mental, physical and social well-being.

Why are you interested in laughter?

It's a universal phenomenon, and one of the most common things we do. We laugh many times a day, for many different reasons, but rarely think about it, and seldom consciously control it. We know so little about the different kinds and functions of laughter, and my interest really starts there. Why do we do it? What can laughter teach us about our positive emotions and social behaviour? There's so much we don't know about how the brain contributes to emotion and I think we can get at understanding this by studying laughter.

So why do people laugh so much?

Only 10 or 20 per cent of laughing is a response to humour. Most of the time it's a message we send to other people--communicating joyful disposition, a willingness to bond and so on. It occupies a special place in social interaction and is a fascinating feature of our biology, with motor, emotional and cognitive components. Scientists study all kinds of emotions and behaviour, but few focus on this most basic ingredient. Laughter gives us a clue that we have powerful systems in our brain which respond to pleasure, happiness and joy. It's also involved in events such as release of fear.

My professional focus has always been on emotional behaviour. I spent many years investigating the neural basis of fear in rats, and came to laughter via that route. When I was working with rats, I noticed that when they were alone, in an exposed environment, they were scared and quite uncomfortable. Back in a cage with others, they seemed much happier. It looked as if they played with one another--real rough-and-tumble--and I wondered whether they were also laughing. The neurobiologist Jaak Panksepp had shown that juvenile rats make short vocalisations, pitched too high for humans to hear, during rough-and-tumble play. He thinks these are similar to laughter. This made me wonder about the roots of laughter.

Do you believe other animals laugh too?

You only have to look at the primates closest to humans to see that laughter is clearly not unique to us. I don't find this too surprising, because we're only one among many social species and there's no reason why we should have a monopoly on laughter as a social tool. The great apes, such as chimpanzees, do something similar to humans. They open their mouths wide, expose their teeth, retract the corners of their lips, and make loud and repetitive vocalisations in situations that tend to evoke human laughter, like when playing with one another or with humans, or when tickled. Laughter may even have evolved long before primates. We know that dogs at play have strange patterns of exhalation that differ from other sounds made during passive or aggressive confrontation.

But I think we need to be careful about over-interpreting panting behaviour in animals at play. It's nice to think of it as homologous to human laughter, but it could just be something similar but with entirely different purposes and evolutionary advantages.

Everything humans do has a function, and laughing is no exception. Its function is surely communication. We need to build social structures in order to live well in our society and evolution has selected laughter as a useful device for promoting social communication. In other words, it must have a survival advantage for the species.

Do you think we have 'laughter genes'?

I'm sure that laughter has been selected by evolution as a useful device for promoting social communication. But we have yet to discover which genes command the enormously complex chain of physiological events which accompany laughter generation.

How have people studied those events?

There have been some studies using advanced brain-imaging techniques such as positron emission tomography and functional magnetic resonance imaging, as well as older-style tests such as electro-encephalography. They've really helped us to understand which bits of the brain are involved in which bits of emotion--normal or abnormal.

What have they found?

The brain scans are usually done while people are responding to humorous material. You see brainwave activity spread from the sensory processing area of the occipital lobe, the bit at the back of the brain that processes visual signals, to the brain's frontal lobe. It seems that the frontal lobe is involved in recognising things as funny. The left side of the frontal lobe analyses the words and structure of jokes while the right side does the intellectual analyses required to "get" jokes. Finally, activity spreads to the motor areas of the brain controlling the physical task of laughing. We also know about these complex pathways involved in laughter from neurological illness and injury. Sometimes after brain damage, tumours, stroke or brain disorders such as Parkinson's disease, people get "stonefaced" syndrome and can't laugh.

I find it improbable that a purely psychological mass reaction would last so long and be so widespread. Sometimes people have fits of abnormal, inappropriate, unrestrained and uncontrollable laughter dissociated from any social or humour stimulus. Laughter involves motor, emotional and cognitive components, each one located in a specific part of the brain. The American neurologists Hanna and Antonio Damasio suggest that abnormal laughter occurs when structures in the basal part of the brain are damaged. The pathways that normally automatically adjust the execution of laughter to be appropriate to the stimulus for it are disrupted and the brain gets incomplete information about the cognitive and situational context of a potential stimulus--it gets it wrong about whether or not to laugh--resulting in chaotic behaviour. Based on this model, I suggest that a viral infection, probably some kind of encephalitis in the basal part of the brain, provoked the 1962 epidemic. Many of the people affected had fever, and some also had movement disturbances.

We see babies and children laughing with their mothers, and it's easy to assume that they're imitating. But we've studied children who have no opportunity to learn laughter, because they're congenitally blind, deaf, or mute, and found that they can smile and laugh even though they're unable to copy others. It's only the beginning of the story, though, and we need to know more about the differences between laughter in different people.

How is laughter different in people who are blind or deaf?

The groundbreaking study in this area was conducted by the human ethologist Irenaus Eibl-Eibsfeldt. He found that laughter and crying patterns are well-developed in such children. He concluded that these expressions evolved through natural selection. Deaf children have different sound patterns in their laughter, as they have in speech. Blind children seem not to display all the facial components of laughter. We're going to study these differences by statistically analysing the minute variations in laughter between different types of people. We'll video their faces while they laugh in response to various stimuli. Then we'll analyse every millisecond of their facial behaviour and vocalisation.

Does laughter differ between the sexes?

I'm sure it does, particularly the uses to which the sexes put laughter as a social tool. For instance, women smile more than laugh, and are particularly adept at smiling and laughing with men as a kind of "social lubricant". It might even be possible that this has a biological origin, because women don't or can't use their physical size as a threat, which men do, even if unconsciously.

And between cultures?

Cultural differences are certainly part of it. Loud, raucous laughter with exaggerated movements and expressions is considered "unfeminine" in most cultures, and is much more common among men, particularly if they're with other men. In several situations I see laughter used, apparently unconsciously, to help get things as diverse as power, friendship, a lover or truthful behaviour from subordinates. For instance, socially dominant individuals, from bosses to tribal chiefs, use laughter to control their subordinates. When the boss laughs, their minions laugh too. Laughter might be a form of asserting power by controlling the emotional climate of the group, and it also has a dark side. There are theories that laughter and aggression have common origins, with some kinds of laughter in primates apparently being threatening--just look at the way they bare their teeth. That might explain why being laughed at is so unpleasant.

Is it true that laughing can make us healthier?

It's undoubtedly the best medicine. For one thing, it's exercise. It activates the cardiovascular system, so heart rate and blood pressure increase, then the arteries dilate, causing blood pressure to fall again. Repeated short, strong contractions of the chest muscles, diaphragm and abdomen increase blood flow into our internal organs, and forced respiration--the ha! ha!--makes sure that this blood is well oxygenated. Muscle tension decreases, and indeed we may temporarily lose control of our limbs, as in the expression "weak with laughter". It may also release brain endorphins, reducing sensitivity to pain and boosting endurance and pleasurable sensations. Some studies suggest that laughter affects the immune system by reducing the production of hormones associated with stress, and that when you laugh the immune system produces more T-cells. But no rigorously controlled studies have confirmed these effects. Laughter's social role is definitely important. I'm very concerned that today's children may be heading for a whole lot of social ills because their play and leisure time is so isolated and they lose out on lots of chances for laughter.

When children stare at computer screens, rather than laughing with each other, this is at odds with what's natural for them. Natural social behaviour in children is playful behaviour, and in such situations laughter indicates that make-believe aggression is just fun, not for real, and this is an important way in which children form positive emotional bonds, gain new social skills and generally start to move from childhood to adulthood. I think parents need to be very careful to ensure that their children play in groups, with both peers and adults, and laugh more.

March 2002 - Telegraph

Laughter is a part of human behavior all over the world, and it reduces anxiety and lowers blood pressure

We laugh more frequently than we eat, sing or have sex. So why do we know so little about it? David Derbyshire investigates

A is standing a bar when he hears a voice coming from the peanut bowl. "I really like your tie," it says. "You're smashing, you are. You're really lovely."

Surprised, the man picks up his drink, and walks to his table. Passing the cigarette machine, he hears another voice. "You and your wife are ugly, fat and stupid," the voice says.

The man is baffled and asks the barman what is going on. "I'm so sorry," says the barman. "The peanuts are complimentary but the cigarette machine is out of order."

Some people, when hearing that joke, smile. A collection of 17 muscles around their mouth contorts and their eyes crease up.

Others laugh. They emit a series of short vowel-like notes, each around 75 milliseconds long, repeated at regular intervals 210 milliseconds apart.

It's a peculiar response. But then laughter is a funny business. It's part of human behaviour all over the world, irrespective of culture. It takes place whenever two or three people meet informally, when somebody else strokes our feet, when a four-month-old baby sees a familiar smiling face.

It makes us less stressed, lowers our blood pressure and reduces anxiety. It's more common than sex, eating or singing. And yet it remains one of the least understood aspects of human behaviour.

Next week, Ken Dodd and Dr Richard Wiseman, the psychologist behind Laugh Lab, a mass experiment into what makes people laugh, will present an evening exploring comedy and the psychology of laughter as part of Wrexham Science Festival.

"Comedy should not be over-analysed. It is either funny or it isn't," says Dodd, who has been touring Britain with his marathon stage show for almost 50 years.

"Laughter is a safety valve. For instance, people might come to my shows feeling miserable, but I won't let them out again until they're laughing their heads off. I want them to forget their cares and worries for a couple of hours (at least) and that's what they can do by having a good laugh."

Dodd is one of the greatest experts in what Britain finds funny. At his home in Knotty Ash, Liverpool, he has collected more than 20,000 books on the subject. He travels 100,000 miles a year, using a "giggle map" which tells him what jokes go down well in different areas.

"I was fortunate enough to have comedy heroes who were naturally funny and gifted. Performers like Arthur Askey, Ted Ray, Rob Wilton and Tommy Cooper. There is a difference between those who say funny things and those who say things funny," he says. "It can be measured by reaction: it starts with a titter, progresses to a chuckle and then explodes into uninhibited laughter. There is nothing like a full-blooded belly laugh.

"I think it was Freud who once described humour as being as incongruous as a buckled wheel, but the trouble with Freud is that he never played the old Glasgow Empire on a wet Monday night after both Rangers and Celtic had lost on the previous Saturday."

Matt Pritchett, award-winning cartoonist of The Telegraph, is weary of the analysis of comedy. His cartoons - described as the "instant hit" of comedy - are regarded as the funniest in the business.

"It is said that there are only a few types of jokes - such as incongruities, surprises, exaggerations and slapstick. I think it's so hard to explain what makes a joke so funny and I'm not always the best judge of my own stuff," he says.

"The disadvantage of the cartoon is that you cannot set up a joke like a stand-up comic would. But then, it can be more instant. I suppose what I am doing is trying to see the flippant or absurd side of everyday situations."

Freud saw laughter as a release - as a way of converting latent aggression into something more socially acceptable. A joke sets up a tension that is relieved by laughter. It also explains why people laugh when they are nervous or suddenly relieved.

For the philosopher Thomas Hobbes, laughter was an expression of superiority, "nothing else but a sudden glory arising from some sudden conception of some eminency in ourselves, by comparison with the infirmity of others, or with our own formerly".

Researchers have shown that people laugh more if their boss tells a joke. Someone falling over on a banana skin and getting up is funny. But how much more funny is it when the victim is a policeman or politician?

The philosophers Kant and Schopenhauer both explained humour through incongruity. In the joke "two fish in a tank, one turns to the other and says `do you know how to drive this?' " the humour comes from the incongruity. It is the sudden realisation that the word tank is ambiguous that forces the listener to see the sentence from a completely new perspective.

According to Robert Provine, one of the world's leading authorities on laughter, traditional models of laughter may offer insights, but they are "limited" because they put too much emphasis on humour.

As professor of psychology and assistant director of the neuroscience program at the University of Maryland, he has studied laughter in shopping centres, schools, offices and parties for the past two decades.

His most surprising conclusion is that most laughter has little to do with humour.

After studying 1,200 examples of natural laughter in the real world, he found fewer than 20 per cent were linked to humour.

Most laughter follows apparently banal or humourless statements. It occurs during playful behaviour and social bonding.

"Laughter is social, being 30 times less frequent in solitary than social situations. We laugh when alone even less than we smile when alone," says Prof Provine, the author of Laughter: A Scientific Investigation. "Humour should be a footnote in the story about laughter, not vice versa."

Clues to the origin of laughter can be seen in our nearest relatives, the great apes. Chimpanzees make a "ha-ah" panting noise when tickled or playing which is similar to laughter, Prof Provine argues. Because they cannot make more than a single sound in one breath, it "differs from the `ha-ha' sound" of modern human laughter. According to Prof Provine it sounds like "a handsaw cutting wood".

The fact that a primitive form of laughter is found in apes suggests it emerged in our ancestors long before we developed language skills, some time before the split with chimpanzees six million years ago.

It may have evolved as a signal of reassurance and safety - a way of letting others in a group know that there is no danger. It may even have had an even more specific role, acting as a signal that any tickling and play fighting were intended to be safe and non-threatening. Just as chimps laugh during play fights, human adults laugh when mock wrestling or tickling each other.

"Tickle, the most ancient and reliable stimulus of laughter, is undervalued in the literature. Humour is a recently evolved cognitive and linguistic stimulus for laughter, not reflective of laughter's rowdy physical roots," says Prof Provine.

"Laughter is the ritualised sound of the laboured breathing of rough and tumble. Tickle is social - you can't tickle yourself - and has a reciprocal nature. You engage others in the give and take of tickle battles. The neural mechanism of tickle locks people together in social play."

Jason Rutter, a sociologist at the Centre for Research on Innovation and Competition, at the University of Manchester, studied the reactions of the audience at dozens of stand-up comedy shows and found that only a small amount of laughter was triggered by traditional punchlines or jokes.

The skills used by comedians to provoke laughter go far beyond telling jokes. According to Dr Rutter, in a comedy routine, the comedian gives cues to the audience to laugh. The audience knows the rules of comedy, and usually wants to be entertained.

The rhetorical tricks used by comedians are close to those used by politicians - such as trotting out lists of threes and setting up opposites.

"Certainly jokes are important, but in a stand-up comedy routine, it's hard to say that the jokes are causing the laughter," says Dr Rutter.

"As Frank Carson said, it is indeed the way that you tell them rather than the jokes themselves that are the most important. We recognise the rhetoric of comedy as tools for showing us where the opportunities to laugh are.

"Laughter does not just happen or erupt out of a response to a joke stimulus. It is negotiated."

"On average people laugh 18 times a day, but the spectrum is huge," says Dr Wiseman, of the University of Hertfordshire.

"Some of it is related to mood, but there may be differences in the brain that can explain why some people laugh more. Verbal humour lights up the parts of the frontal cortex involved in resolving ambiguities, flexible thinking and seeing situations from a different point of view.

"So it could be that people who laugh more are resolving ambiguities more quickly. Or it could be personality related. Some people find slapstick funnier than wordplay, but laugh less because there is less slapstick out there to laugh at.

"The people who laugh more cope better with the stress of daily life, they live longer and are healthier. Laughter also helps us to bond with people and communicate with one another and so research into humour is far from trivial. It's serious science, a bringing together of red noses and white coats."

1999 - Reuters News

Riddles, jokes and computers can help children improve their reading skills. Developmental psychologists told the annual meeting of The British Psychological Society that training youngsters to understand and make up riddles and jokes can improve their reading comprehension.

Different types of linguistic awareness seem to underpin decoding and comprehension skills, and riddle training is potentially useful in remediating poor comprehension. A professor at the University of Sussex has conducted two studies to develop programs to help children whose reading progress drops around the age of seven to nine.

Forty children were given standardized reading tests for accuracy and comprehension and were also asked to choose appropriate punchlines for ambiguous riddles to improve their linguistic awareness.The children with the highest number of correct riddles had better comprehension scores.

In the second study, an equal number of pupils had either riddle, absurdity or story reading training. The students who had practiced with riddle training and absurdity also improved their comprehension skills.

Riddles and jokes are focusing on double meanings. You're sitting back from the text and reflecting on the meaning of the text.

Laughter is a primitive reflex common to most animals not just humans