How much art can a brain take?

Man does not live by bread alone; nor by know-how, safety, children, or sex. People everywhere spend as much time as they can afford on activities that, in the struggle to survive and reproduce, seem pointless. In all cultures, people tell stories and recite poetry. They joke, laugh, and tease. They sing and dance. They decorate surfaces.

As if that weren't enough of a puzzle, the more biologically frivolous and vain the activity, the more people exalt it. Art, literature, and music are thought to be not just pleasurable but noble. They are the mind's best work, what makes life worth living. Why do we pursue the biologically trivial and futile and experience them as sublime? To many educated people the question seems horribly philistine, even immoral. But it is unavoidable for anyone interested in the makeup of Homo sapiens. Members of our species do mad deeds like living for their art and (in India) selling their blood to buy movie tickets. Why? How might we understand the psychology of the arts within the modern understanding of the brain as a biological organ shaped by the forces of evolution?

Every university has a faculty of arts, which usually dominates the institution in numbers and in the public eye. But the tens of thousands of scholars and millions of pages of scholarship have shed almost no light on the question of why people pursue the arts at all. The function of the arts is almost defiantly obscure, and I think there are several reasons why.

One is that the arts engage not only the psychology of aesthetics but also the psychology of status. The very uselessness of art that makes it so incomprehensible to the evolutionary biologist makes it all too comprehensible to the economist and social psychologist. What better proof that you have money to spare than your being able to spend it on doodads and stunts that don't fill the belly or keep the rain out but that require precious materials, years of practice, a command of obscure texts, or intimacy with the elite?

The grand styles of one century become tacky in the next, as we see in words that are both period labels and terms of abuse ("gothic", "mannerist", "baroque", "rococo"). The steadfast patrons of the arts are the aristocracy and those who want to join them. Modern and postmodern works are intended not to give pleasure but to confirm or confound the theories of a guild of critics and analysts, to epater les bourgeois, or to baffle the yokels.

Academics and intellectuals are culture vultures. In a gathering of today's elite, it is perfectly acceptable to laugh that you barely passed Physics for Poets and Rocks for Jocks and have remained ignorant of science ever since, despite the obvious importance of scientific literacy to informed choices about personal health and public policy. But saying that you have never heard of James Joyce or that you tried listening to Mozart once but prefer Andrew Lloyd Webber is as shocking as blowing your nose on your sleeve or announcing that you employ children in a sweatshop. The blending in people's minds of art, status and virtue is an extension of Bell's principle of "sartorial morality": people find dignity in the signs of an honourably futile existence removed from all menial necessities.

I mention these facts not to denigrate the arts but to clarify an important mystery in understanding ourselves. Of course we find pleasure and enlightenment in contemplating the products of the arts, and not all of it is a pride in sharing the tastes of the beautiful people. But to understand the psychology of the arts, we must leave at the door our terror of being mistaken for the kind of person who prefers Lloyd Webber to Mozart. We need to begin with folk songs, pulp fiction and paintings on black velvet, not Mahler, Eliot and Kandinsky. And that does not mean compensating for our slumming by dressing up the lowly subject matter in highfalutin "theory" (a semiotic analysis of Bugs Bunny, a psychoanalytic exegesis of James Bond, a deconstruction of Vogue). It means asking a simple question: What is it about the mind that lets people take pleasure in shapes and colours and sounds and stories and myths?

One route to the pleasure circuits is via the senses, which stimulate the circuits when they are in environments that would have led to fitness in past generations. Now, if the intellectual faculties could identify the pleasure-giving patterns, purify them and concentrate them, the brain could stimulate itself without the messiness of electrodes or drugs. It could give itself intense artificial doses of the sights and sounds and smells that ordinarily are given off by healthful environments. We enjoy strawberry cheesecake, but not because we evolved a taste for it. We evolved circuits that gave us trickles of enjoyment from the sweet taste of ripe fruit, the creamy mouth feel of fats and oils from nuts and meat, and the coolness of fresh water. Cheesecake packs a sensual wallop unlike anything in the natural world because it packs megadoses of agreeable stimuli concocted for the express purpose of pressing our pleasure buttons. Pornography is another pleasure technology. Art may be a third.

The visual arts are one example of a technology designed to defeat the locks that safeguard our pleasure buttons and to press the buttons in various combinations. Vision solves the unsolvable problem of recovering a description of the world from its projection on to the retina by making assumptions about how the world is put together. Optical illusions, including paintings, photographs, movies and television, cunningly violate those assumptions and give off patterns of light that dupe our visual system into seeing scenes that aren't there.

That's the lock-picking. The pleasure buttons are the content of the illusions. Everyday photographs and paintings (the ones that most people hang in their living rooms, though not necessarily the ones you would see in a museum) depict plants, animals, landscapes and people. Many biologists believe that the geometry of beauty is the visible signal of adaptively valuable objects: safe, food-rich, explorable, learnable habitats, and fertile, healthy mates and offspring.

It's helpful to distinguish delight, perhaps the product of a useless technology for pressing our pleasure buttons, from instruction, perhaps a product of a cognitive adaptation. The technology of fiction delivers a simulation of life that an audience can enter in the comfort of their cave, couch, or cinema seat. Words can evoke mental images, which can activate the parts of the brain that register the world when we actually perceive it. Other technologies violate the assumptions of our perceptual apparatus and trick us with illusions that partly duplicate the experience of seeing and hearing real events. They include costumes, makeup, sets, sound effects, cinematography and animation. Perhaps in the near future we can add virtual reality to the list, and in the more distant future the feelies of Brave New World. When the illusions work, there is no mystery to the question "Why do people enjoy fiction?". It is identical to the question "Why do people enjoy life?". When we are absorbed in a book or a movie, we get to see breathtaking landscapes, hobnob with important people, fall in love with ravishing men and women, protect loved ones, attain impossible goals, and defeat wicked enemies. Not a bad deal for pounds 6.50.

Another key pleasure button is the one labelled "gossip". Gossip is a favourite pastime in all human societies because knowledge is power. Knowing who needs a favour and who is in a position to offer one, who is trustworthy and who is a liar, who is available (or soon to become available) and who is under the protection of a jealous spouse or family - all give obvious strategic advantages in the games of life. That is especially true when the information is not yet widely known and one can be the first to exploit an opportunity, the social equivalent of insider trading. In the small bands in which our minds evolved, everyone knew everyone else, so all gossip was useful. Today, when we peer into the private lives of fictitious characters, we are giving ourselves the same buzz.

Literature, of course, not only delights but instructs. Fictional narratives might work a bit like experiments. The author places a fictitious character in a hypothetical situation in an otherwise real world, and allows the reader to explore the consequences. Once the fictitious world is set up, the protagonist is given a goal and we watch as he or she pursues it in the face of obstacles. We watch what happens to them and mentally take notes on the outcomes of the strategies and tactics they use in pursuing their goals.

What are those goals? A Darwinian would say that ultimately organisms have only two: to survive and to reproduce. And those are precisely the goals that drive the human organisms in fiction. Most of the 36 plots in Georges Polti's catalogue, The Thirty-Six Dramatic Situations, are defined by love or sex or a threat to the safety of the protagonist or his kin (for example, "Mistaken jealousy", "Vengeance taken for kindred upon kindred" and "Discovery of the dishonour of a loved one"). The difference between fiction for children and fiction for adults is commonly summed up in two words: sex and violence. The American movie critic Pauline Kael got the title for one of her books from an Italian movie poster that she said contained "the briefest statement imaginable of the basic appeal of the movies": Kiss Kiss Bang Bang.

Sex and violence are not just the obsessions of pulp fiction and trash TV. The writers Richard Lederer and Michael Gilleland present the following tabloid headlines:

Doctor's wife and local minister exposed for conceiving illegitimate daughter

Teenagers commit double suicide; families vow to end vendetta

Student confesses to axe murder of local pawnbroker and assistant

Madwoman long imprisoned in attic sets house on fire, then leaps to death

Sound familiar? They are the plots of The Scarlet Letter, Romeo and Juliet, Crime and Punishment and Jane Eyre. Fictional narratives supply us with a mental catalogue of the conundrums we might face some day and the strategies we could deploy against them. The cliche that life imitates art is true because the function of some kinds of art may be for life to imitate it. But if we really want to understand this strange and eternally fascinating quirk of the human brain, we cannot just exalt the finest examples. We have to look at the typical examples, and the mixture of motives that draws people to them.

This is adapted from Steven Pinker's `How the Mind Works', Penguin, pounds 9.99. Steven Pinker and Richard Dawkins debate the motion "Is science killing the soul?" at Westminster Central Hall on Wednesday 10 February, 7pm.