Steven Pinker's deconstruction of the mind suggests that our 20th century leisure pursuits are driven by primitive genetic imperatives. Tim Cornwell reports

Steven Pinker is a movie buff - or was, he says, until Hollywood sank to "bloodbaths and bad comedies". As a scientist writing in popular mode, he cites Star Trek, Animal House and The Godfather, on, respectively, the emotions, the nature of humour, and family dynamics. So it is apt to use a film analogy and say that his new book, How the Mind Works, leaves the reader second-guessing the simplest human pleasures in the manner of Data, the newest Star Trek android.

For Pinker makes the claim (which seems ridiculous at first glance) that our 20th-century leisure pursuits are driven by the genetic imperatives of the Stone Age. Savouring a magnificent view, we are merely exercising our ancestral instinct for exploring landscape, particularly one that resembles the African savannah. An accompanying sunset is evocative because it warns of an "imminent and consequential change" - red sky at night, shepherd's delight. We crane our necks to get a better view at the zoo not because the animals are fluffy or cute, but because we are eyeing the lunch menu. "Our fascination with animals is obvious," Pinker writes dismissively. "We eat them, they eat us."

The discussion of Darwin is back on the agenda. A relatively new school of Darwinian theory, evolutionary psychology, lays down how evolution shaped not just our bodies, but our thoughts too. It has found a champion in Pinker, professor at the Massachusetts Institute of Technology.

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Steven Pinker made his name with The Language Instinct, an investigation of how language works and where it comes from. A bestseller, it drew on his (and others', notably Noam Chomsky's) research. Now comes How the Mind Works. Pinker has moved from speciality to a Big Book, the "grand synthesis", according to the cover notes. Stephen Hawking called time, James Gleick brought chaos, now Pinker blows the mind. The key to the complex structure of the mind is set out in his opening chapter: "The mind is a system of organs of computation, designed by natural selection to solve the kinds of problems our ancestors faced in their foraging way of life, in particular, understanding and outmanouvring objects, animals, plants, and other people." Its primary functions can be divined by reverse engineering, taking the mind like an olive-pitting machine and working backwards to discover its component parts.

The 43-year-old son of a travelling salesman, Steven Pinker's image is that of a populist academic with a flair for self-promotion, who sports boots and jeans and "looks less like a professor than an FM-lite rock star", in the words of one US writer. But he insists he's no rebel. "My lifestyle is conservative. I'm not terribly different from other academics. I don't drive a motorcycle. I don't take drugs. Most of my life is spent writing, reading and going to conferences. I do have long hair, I wear colourful ties, I listen to rock music."

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Nor does he have children. A man who embraces Oxford professor Richard Dawkins's theory of The Selfish Gene - the notion that, driven by our genes, our primary evolutionary purpose is to reproduce - takes a wicked pleasure in shirking his genetic duty. "Well into my procreating years I am, so far, voluntarily childless, having squandered my biological resources reading and writing, doing research, helping out friends and students, and jogging in circles, ignoring the solemn imperative to spread my genes," he writes. "By Darwinian standards I am a horrible mistake, a pathetic loser, not one iota less than if I were a card-carrying member of Queer Nation. But I am happy to be that way, and if my genes don't like it, they can go jump in the lake."

In interview, Pinker adds that he and his wife "enjoy our lives, and each other's company, too much to allow a third party to intrude." It strikes me, as a father of two small children, that this happily childless state presumably accounts for the superior tone of a chapter on "family values". In it, Pinker posits that wicked stepmothers, sibling rivalry, kissing cousins and infanticide are all products of emotions fired by genes striving to reproduce themselves. When two-thirds of British and American mothers confess to loving one child more than another, he suggests, it is really their genes investing in winners and losers.

The Canadian-born Pinker was raised in Montreal. After graduating from McGill University, he took his doctorate in psychology at Harvard, where he encountered Chomsky's teaching at nearby MIT. Pinker would build from Chomsky's theory that we are born with an innate ability to acquire language - with brains "hard-wired" to master nouns and verbs. (Though not, Pinker insists, for reading or maths - suggesting that these subjects must be taught the old-fashioned way and not acquired by repeated exposure.) In the late 1980s, Pinker read the early work of psychologist Leda Cosmides and her husband, anthropologist John Tooby, who first coined the phrase "evolutionary psychology". There are 13 references to Tooby and seven to Cosmides at the end of How the Mind Works. It was written when he took a year's fellowship at UC Santa Barbara, home to their Center for Evolutionary Psychology.

Evolutionary psychology applies Dawkins-style Darwinian theory to the workings of the mind. It chastises those "romantics" who put the intellect on some kind of pedestal, aloof from grubby animal instincts, immune to the command: go forth and multiply. It holds that the brain is an information-processor organised into specialised modules. Just as genetic mutation and natural selection allowed the "blind watchmaker" to develop such organs as the hand or eye, so the "blind programmer" favoured the most efficient brain segments. People survived and thrived - replicating their genes - when their brains were effective in information retrieval or decision-making, in directing flight from danger or detecting fraud, in making allies or choosing mates.

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Logical skills, emotions, family relations, love of art, in Pinker's world, are byproducts of genetic replication. Using "reverse engineering", Pinker suggests that counting ability was born of the need to estimate the food on a patch of forage or what has happened when three bears go into a cave and two come out. The universal thirst for vengeance developed to warn others against killing.

Within the family, step-parenthood is the strongest risk factor for child abuse because there is no genetic common ground with the child. Post-natal depression is a prelude to the mother's decision about whether her latest offspring is a worthy candidate to nurture to adulthood; if not, infanticide may follow. As for a person's love of novels or films: "The technology of fiction delivers a simulation of life that an audience can enter in the comfort of their cave, couch, or theatre seat."

Would Darwin, however, have accepted that the herd instinct leads speeding drivers to bunch in convoys? Pinker's book prompted a blast against strident "Darwinian fundamentalism" by Harvard paleontologist Stephen Jay Gould, in The New York Review of Books. Gould quotes Darwin himself, issuing a warning against using those who would simplify and caricature his work as a catch-all theory. "I am convinced that natural selection has been the main but not the exclusive means of modification," Darwin wrote, in the preface to the 1872 edition of The Origin of Species. Gould, who calls himself a "Darwinian pluralist", cites "geological moments" and mass extinctions against the idea that individual species evolved strictly via a series of tiny genetic changes generation after generation.

More pointedly, Gould compares evolutionary psychology to "pure guesswork in the cocktail party mould", searching for speculative motives for modern behaviour. "How can we possibly know in detail," Gould asks, "what small bands of hunter-gatherers did two million years ago?" Or how relations of kinship, male and female roles, religion or storytelling evolved? Pinker fired back with a letter accusing Gould of being confused, "discourteous" and uninformed.

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Evolutionary psychology has implications for psychotherapy, according to Pinker. If anxiety and depression are programmed into us, for example, "it may not always be best to nullify them with drugs willy-nilly". He has nothing but scorn for Freud's notion of Oedipal crushes; children have motives for blocking the production of rival siblings, but not for marrying their mothers. At the same time, we do not consciously promote our genes; you cannot use evolutionary psychology to predict individual reactions. Not everyone is rushing out to clone themselves and we enjoy sex but are quite willing to use contraception.

Steven Pinker's writing style is an object lesson for any academic hoping to make the bestseller lists. But when the going gets tough, the tough reach for an anecdote. By the end of the book the constant dipping into popular culture becomes downright irritating. Hugh Grant, Robert Redford and Heidi Fleiss turn up in the space of less than a page, as part of a discussion of why men would pay women for sex (men are driven by the impulse to impregnate as many women as possible; women seek a provider who will help them nurse their genetic offspring through life.) Mae West, Jimmy Connors, Woody Allen and the Dalai Lama make appearances; so does the Dunblane massacre. Pinker seems to have less patience for high culture; he suggests that loving abstract music or art is an act of status-seeking or "cultural machismo".

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But having argued that we are formed by genetic forces beyond our ken, he ends on a curious calling to some higher intelligence and morality. Evolutionary theory cannot explain our unshakable conviction "that some acts are inherently wrong". It cannot untangle the conundrums of free will or consciousness, he says, just as our minds are unable to retain 10,000 words in short-term memory, or see in ultraviolet light. "So why should there not be creatures with more cognitive faculties than we have, or with different ones? " he asks. "The most undeniable thing there is, our own awareness, would be forever beyond our conceptual grasp. But if our minds are part of nature, that is to be expected, even welcomed."

* How the Mind Works (Allen Lane, Pounds 25)