('I'll get an award for this and meet interesting women'). It's like driving on a quiet motorway: a lot of the thinking has been taken out of it.

Our ancestors honed that ability, to consider alternative scenarios. And within any of those scenarios, the ability to make a story of what was happening was a very powerful way to remember it and to communicate it. And, particularly, to employ it as a parable, to direct your future action or that of your children. Human beings need a very long time to get that brain upand- running, at least twice as long as their brother and sister chimpanzees. That is why threeyear- old chimps are nearly adult in chimp behaviour, and can do some of the mental tricks of six- or seven-year-old children.

But the young chimps don't hear stories. Our children have been hearing stories since they recognised any words at all, and by three years old they are making up their own stories about what is happening around them. We are all impressed by their vocabulary skills, and by their acquisition of syntax and semantics; but we should also note how good they are at making narratives out of events. From about five years old, they get their parents to do things for them by placing those things in narrative context. And most of their games with peers have a context, within which stories are played out. The context they create is just like that of the animal and fairy stories we tell them. The parents don't instruct the child how to do this, nor do the children have to elicit the 'right' storytelling behaviours from their parents. This is an evolutionary complicity. It seems very natural -after all, we are Pan narrans -that we tell stories to children, and that children and parents enjoy the activity. We learn about 'narrativium' very early in our development, and we use it and promote it for the whole of our lives.

Human development is a complex, recursive behaviour. It is not simply reading out DNA

'blueprints' and making another working part (contrary to the new folk-biology of genes). To show you how truly remarkable our development is, despite seeming so simple and so natural, let's have a look at some earlier parent-child behaviour.

Keep in mind a distinction that is being imported into more and more scientific thinking, that between 'complicated' and 'complex'. 'Complicated' means a whole set of simple things working together to produce some effect, like a clock or an automobile: each of the components -brakes, engine, body-shell, steering - contributes to what the car does by doing its own thing, pretty well.

There are some interactions, to be sure. When the engine is turning fast, it has a gyroscopic effect that makes the steering behave differently, and the gearbox affects how fast the engine is going at a particular car speed. To see human development as a kind of car assembly process, with the successive genetic blueprints 'defining' each new bit as we add them, is to see us as only complicated.

A car being driven, however, is a complex system: each action it takes helps determine future actions and is dependent upon previous actions. It changes the rules for itself as it goes. So does a garden. As plants grow, they take nutrients from the soil, and this affects what else can grow there later. But they also rot down, adding nutrients, providing habitat for insects, grubs, hedgehogs ... A mature garden has a very different dynamic from that of a new plot on a housing estate.

Similarly, we change our own rules as we develop.

There are always several superficially different, non-overlapping descriptions of any complex system, and one way to deal with a complex system is to collect these descriptions and choose appropriate ones for different ways of influencing its behaviour.46 An amusingly simple example can be seen in many French and Swiss railway stations and airports: a sign that says LOST PROPERTY OBJETS TROUVES

The French means 'found objects'. But we don't think that this is a case of the English losing objects and the French finding them. It's two descriptions of the same situation.

Now look at a baby in a pram, throwing its rattle out on to the pavement for Mummy, or child- minder, or indeed passers-by, to retrieve. We probably think that the child is not coordinated enough yet to keep its rattle within reach: we think 'Lost Property'. Then we see Mummy give the rattle back to the child, to be rewarded with a smile, and we think 'No, it's more subtle: there is a baby teaching its mother to fetch, just as we adults do with dogs'. Now we think 'Objets Trouves'. The baby's smile is itself part of a complex, reciprocal system of rewards that was set up long ago in evolution. We watch babies copy' the smiles of parents -but no, it can't be copying, because even blind babies smile. Anyway, copying would be immensely difficult: from anywhere on the retina, the undeveloped brain must 'sort out' a face with a smile, then work out which of its own muscles to work to produce that effect, without a mirror. No, it's a pre-wired reflex. Babies reflexively react to cooing sounds and to pre-wired recognition of smiles; an upwardly-curved line on a piece of paper works just as well. The 'smile' icon rewards the adult, who then tries hard to keep the baby doing it. The complex interactions proceed, changing both participants progressively.

They can be analysed more easily in unusual situations, such as sighted children with 'signing'

parents, perhaps deaf or dumb, but occasionally as part of a psychological experiment. For example in 2001 a team of Canadian researchers headed by Laura Ann Petitto studied three children, about six months old, all with perfect hearing but born to deaf parents. The parents

'cooed over' the babies in sign language, and the babies began to 'babble' sign language -that is, make a variety of random gestures with their hands -in return. The parents used an unusual and very rhythmic form of sign language, quite unlike anything they would use to adults. Similarly, adults speak to babies in a rhythmic sing-song voice, and between the ages of about six months and a year the babies' babble takes on properties of the parents' specific language. They are rewiring and 'tuning' their sense organs, in this case the cochlea, to hear that language best.

Some scientists think that babbling sounds is just random opening and closing of the jaw, but others are convinced it is an essential stage in the learning of language. The use of special rhythms by parents, and the spontaneous 'babbling' with hand-movements when the parents are deaf, indicate that the second theory is closer to the mark. Petitto suggests that the use of rhythm is an ancient evolutionary trick, exploiting the natural sensitivities of the young child.

As the child grows, its complex interaction with surrounding humans comes to produce wholly unexpected results: what we call 'emergent' behaviour, meaning that it is not overtly present in the behaviour of the components. Where two or more systems interact like this, we call the process a complicity. The interaction of an actor with an audience can build up a wholly new and unexpected relationship. The evolutionary interaction of blood-sucking insects with vertebrates paved the way for protozoan blood parasites that cause diseases like malaria and sleeping- sickness. The car-and-driver behaves differently from either alone (and car-and-driver-andalcohol is even less predictable). Similarly, human development is a progressive interaction between the child's intelligence and the culture's extelligence: a complicity. This complicity progresses from simple vocabulary-learning to the syntax of little sentences and the semantics of fulfilling the child's needs and wants and the parents' expectations. The beginning of storytelling then becomes an early threshold into worlds that our kin the chimpanzees know not of.

The stories that all human cultures use to mould the expectations and behaviour of the growing child use iconic figures: always some animals, and then status-figures of the culture (princesses, wizards, giants, mermaids). These stories sit in all our minds, contributing to our acting, our acting-out, our thinking, our predicting what will happen next, as caveman or cameraman. We learn to expect outcomes of particular kinds, frequently expressed in ritual words ('And they all lived happily ever after' or 'So it all ended in tears').47 The stories that have been used in England over the centuries have changed in complicity with the changing culture -making the culture change, and responding to those changes, like a river changing its path across a wide flood-plain that it has itself built. The Grimm Brothers and Hans Christian Andersen were but the last of a long series, with Charles Perrault accumulating the Mother Goose tales around 1690; there were many collections before that, especially some interesting Italian groupings and retellings for adults.