We all appreciate the importance of humour. It can lift the glummest of moments, forge a friendship, and relieve stress after a hard day at work.

In relationships, a sense of humour rates consistently highly in surveys of desirable qualities in a partner, often beating physical attraction to the top of the list. So much store do we set in humour, that incompatibility of what we find amusing can damage or even break a relationship for good. But humour is not only vital to a successful relationship. A new understanding of its workings tells us that it has helped human beings to evolve into the intelligent species we are today, and may play a vital role in childhood development.

In recognition of the importance of humour, announcement of the shortlist for Booktrust's first Roald Dahl Funny Prize, awarded to outstanding books for children aged 6 or under, and 7 to 14 was made this week.

So what is humour, and why is it so important? By studying more than 10,000 examples, ranging from stock formats such as sarcasm and slapstick, through to individual instances of both popular and high-brow comedy, we began to notice a pattern. What the research tells us, essentially, is that the brain finds something amusing when it recognises a pattern that surprises it. These patterns take a variety of different forms, from simple repetition to more complex variations. The reason we are beginning to understand this only now is because the process of recognising the patterns is unconscious.

Why then have we developed humour? Did it really help us to escape the jaws of a sabre-tooth tiger? Well, in a way, yes. On an evolutionary level, the ability to recognise patterns instantly and unconsciously is a remarkable asset, unparalleled in the animal kingdom. The rewards of humour encouraged human beings to develop a remarkable adaptability to new circumstances.

But patterns alone are not enough. The necessary element of surprise in humour means that our attention is drawn to those patterns that are novel or unexpected. In short, through the faculty of humour we evolved into the thoughtful, problem-solving, quick-witted and successful species we are today.

There are many amazing implications of our new understanding of humour. There is now the certainty that one day we will be able to produce an artificial intelligence that benefits from a sense of humour. But perhaps the most engaging is the light it throws on childhood development. It is now clear that when an infant laughs he or she is responding to the same stimuli as an adult - recognising patterns that surprise them.

Children laugh before they can speak

Even the earliest laughter evoked by peek-a-boo is stimulated by surprise repetition. If the build-up is too obvious the child may not laugh. But while there is the slightest uncertainty about how, when or if the next stage will arrive, the potential for humour remains.

After peek-a-boo children generally progress to clap-hands and face-pulling, each representing a developmental stage. In fact, there is a direct correlation between the stages of childhood development and humour, suggesting that humorous games play a crucial role in honing an infant's perceptual abilities. However, it's important to note that a tendency not to laugh does not automatically imply a failure to recognise patterns. It can just as frequently signal that a child finds the amusement tedious or predictable.

A sense of humour develops early. Children laugh long before they start to speak. Interestingly, the same patterns then have to be relearnt for linguistic humour somewhere between the ages of 6 and 9.

Wordplay and the structures of jokes often cause a child significant difficulties when first attempting to emulate them, but by getting to grips with linguistic humour, a child completes the final stage of humorous development. Enthusiasm for the written word can contribute significantly to this, a point not lost on the Children's Laureate, Michael Rosen, a member of the judging panel for the annual Roald Dahl Funny Prize. “Through print we are most able to get hold of abstract ideas, to take on board the idea of multiple viewpoints and to handle complex, interwoven thoughts. It is vital, therefore, that we find materials that enable children to find the printed word attractive and exciting. Humour is one of the tickling sticks we have to do this.”

Beyond teething problems with language, the basis of childhood humour is identical to its adult counterpart, providing unique opportunities to bridge emotional and intellectual distances between generations. For younger children, reading along with adults provides confirmation that verbal and linguistic humour are just as fun as their equivalents in the physical world, and can forge an important bond between adult and child. With or without a comprehension of the science, it is easy to see the benefits of such interaction.

Humour is a very serious matter

Although we laugh at different things as we get older the mechanism of humour remains the same, but at the same time our changing experiences mean that we will recognise and be surprised by different patterns.

Such shifts remind us that we cannot dictate what people should or should not find amusing. Although we can explain how and why we find something humorous, the perception of what is funny belongs with the individual, whether adult or child. At the other end of the scale, humour has contributed fundamentally to the success of the species, playing a vital role in the development of the unique intellectual and perceptual abilities, and is a very serious matter indeed.

Alastair Clarke is an evolutionary theorist and author of The Pattern Recognition Theory of Humour (Pyrrhic House). www.pyrrhichouse.co.uk For more information about Booktrust's Roald Dahl Funny Prize visit www.roalddahlprize.org

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