The Evolution of Laughter and the Edinburgh Fringe.

I have just returned from a great 10 days at the Edinburgh fringe festival of comedy. Having watched over 100 acts perform (and performed myself) I have been thinking about the evolution of laughter. I saw some brilliant performances by (amongst others) Paul Foot, Trevor Lock, Baba Brinkman, (Rap Guide To Religion / The Rap Canterbury Tales / Off The Top with his brilliant neuroscientist wife Dr. Heather Berlin) and the very wrong Lewis Schaffer. But I also saw some terrible, excruciating performances by those struggling with their art and the very nature of laughter. They are heroes too. All comics will die on stage at some point in their career. By dying on stage, I don’t mean like Tommy Cooper on 15 April 1984, whom collapsed on the stage of Her Majesty's Theatre and died. At that moment he was relieved of life but invested with immortality.

When I go I want to be on stage I want the audience laughing and everyone happy.

In comedic terms ‘dying’ means the very act of going on stage and nobody laughing (or worse one person laughing, perhaps only once). It is part of the growth of a comic, his or her evolution and his / her curse. We have all died. Some more than others. The importance of other people laughing is often forgotten. It is why in America they are so keen on ‘canned’ or taped laughter tracks. So try watching Friends Without Laughter Soundtrack is Creepy!

Interestingly it appears that laughter is like the viral contagion de jour, Ebola. On Jan. 30, 1962, three schoolgirls started giggling in a boarding school classroom in the northeastern corner of what is now Tanzania—and touched off a very strange epidemic. The three couldn’t stop laughing—and soon the uncontrollable cackles spread to their classmates. The laughing attacks lasted from a few minutes up to a few hours; one poor girl reportedly experienced symptoms for 16 straight days. Victims couldn’t focus on their schoolwork, and would lash out if others tried to restrain them.

When 95 of the school’s 159 pupils had come down with what came to be known asomuneepo, the Swahili word for laughing disease, the school shut down. The students returned to their villages, taking omuneepo with them. The affliction spread from person to person, school-to-school, village to village. The education of the children is being seriously interfered with and there is considerable fear among the village communities, noted local medical officers in a 1963 report in the Central African Journal of Medicine. They could find no explanation for the matter. When the epidemic finally died down months later, roughly a thousand people had been struck by the laughing disease.

But why do audiences laugh? Or indeed rats? Yes rats do laugh when tickled. A bit like being at Spank! at 1am, in the Underbelly of Edinburgh (an out-of-control, shambolic, rodent like comedy show that is also an amazing success). What is the trigger for this unconditional laughter? One of the more complex aspects of human behaviour is our universal ability to laugh. Laughter has puzzled behavioural biologists for many years because it is hard to imagine how this strange behaviour has evolved. Why would laughing individuals be fitter in reproductive terms? And why is this ability is built-in, like sneezing, rather than something we learn, like hunting?

It appears to be linked to evolution of the tickle response. In 1897, psychologists established that there are two kinds of tickles. Knismesis is caused by very light movement across the skin. It doesn’t make you laugh, and is sometimes accompanied by an itching sensation. Knismesis is often caused by animals and insects crawling across the skin, and may have evolved in a wide range of species as adaptive defense from things like ticks, fleas, mosquitoes, scorpions and spiders.

Gargalesis is the other tickle, the laugh-producing one caused by applying pressure to ticklish areas. Gargalesis laughter gets you into a very small club that includes humans, chimps, gorillas, orangutans and, surprisingly, rats. Baba Brinkman will have a field day with the evolution of this complex event….maybe his next work will be the rap guide to laughter?

Biologists think gargalesis evolved in primates as a means of social bonding and self-defense development (since it provides lots of practice protecting your neck, ribs and (under)belly). Primates’ tickling laughs all share some sonic similarities, too, leading researchers to think that the reaction began with one of our common ancestors.

Rat laughter, meanwhile doesn’t really sound like anything we’d recognise among apes, and consists of pulsating, high-frequency ultrasonic chirps, starting with a vocalised inhalation. Washington State University researcher Jaak Panksepp, who discovered rats’ tickle laughter in 2007, says the rodents are particularly ticklish in their nape area, which is where juveniles often target play activities such as pinning each other down. He also found that tickling rats to the point of laughter seemed to promote bonding and tickled rats would seek out specific lab workers’ hands that had tickled them before.

More animals may laugh when tickled, but researchers haven’t found them yet. They’re looking, though, in the same place the rest of us go to see animals being tickled: YouTube. Marina Davila-Ross from the University of Portsmouth has been poring over the large amount of animal footage on YouTube for animals reacting noisily to tickling. She is collecting examples to assess whether the noises count as laughter, or are positive vocalisations signaling happiness.

The evolution of laughter, they say, is intimately linked with the evolution of the human brain, itself a puzzle of the highest order. There is widespread belief that the brain evolved rapidly at the same time as human group sizes increased. Bigger groups naturally lead to greater social complexity. And it’s easy to imagine that things like language and complex social behaviours are the result of brain evolution. But the latest thinking is more subtle; more like the brilliant Trevor Lock.

Known as the social brain hypothesis, this holds that the brain evolved not to solve complicated ecological problems such as how to use tools, how to hunt more effectively and how to cook. Instead, the brain evolved to better cope with the social demands of living in larger groups. In chimps, an important aspect of social behaviour is grooming, something they can spend up to 20 per cent of their time doing. Grooming is an activity that takes place in pairs. It is important because it establishes and strengthens bonds between individuals. However, there is a clear practical limit to the number of individuals you can bond with in this way before you begin to starve.

The social brain hypothesis is that language evolved as a way of establishing and strengthening bonds with larger numbers of individuals in a shorter a period of time. Conversation can easily include up to 10 individuals and would have been a skill that dramatically improves the fitness of these individuals for life in the group. Since the act of talking limits the number of individuals who can take part in a conversation, laughter is a method that individuals use to signal their participation in larger group chats. And the result of all this extra bonding is that the larger group, and hence the individuals within it, flourishes.

Laughter is a similar kind of release and the intellectual momentum that builds up during conversation needs to be relieved, either through verbalisation or some other mechanism. But without anything specific to say, the result is the kind of panting and cackling that we call laughter. That’s why it is built in. This social significance of this behaviour is the thing that has evolved, not the activity itself.

This interesting idea is a synthesis of ideas from a mind-boggling array of disciplines: neuroimaging, neurophysiology, sound analysis, physiology as well as evolutionary theory and now comedy, to name just a few.

Laughter, in other words, is more than just a response to humour. It’s a primal human tool, one of the building blocks of society. It taps into the core of what we are as social creatures, expressing from one person to another what often cannot be said in any other way: either that everything is in good fun—or, as in the case of omuneepo, that something is very, very wrong.

Like one of Lewis Schaffer’s jokes.