EVOLUTIONARY POP STAR

By J. MADELEINE NASH

His shoulder-length hair bouncing, Steve Pinker strides into the lecture hall like a rock star taking center stage. He flings his leather jacket over the back of a chair, fingers some chords on an electronic keyboard and flicks on his microphone. Over the next hour and a half, Pinker, director of the Center for Cognitive Neuroscience at the Massachusetts Institute of Technology, will treat 325 undergraduates to a series of demonstrations highlighting design glitches in that evanescent thing we call the mind.

He starts by projecting stereograms--two-dimensional images that produce three-dimensional illusions--onto a big movie screen. As the students stare, a pattern of chain-saw-wielding teddy bears magically gives rise to the image of a large, headless bear that seems to hover in space. Sometimes, explains Pinker, 43, the mind "sees" things that are not really there.

Why? In his new book, immodestly titled How the Mind Works (Norton; $29.95), Pinker suggests an intriguing if highly controversial answer. The mind, he says, is like an ancient, jerry-built computer program made up of dozens of specialized "modules," each honed by hundreds of thousands, if not millions, of years of evolution. There are modules for stereo vision and manual dexterity, for understanding numbers and grammatical speech, for sexual jealousy and romantic love. Don't think of them as "detachable, snap-in components," he cautions. They're not visible to the naked eye "like the rump steak on the supermarket cow display." A mental module, he says, "probably looks more like roadkill, sprawling messily over the bulges and crevasses of the brain."

If How the Mind Works offers a smooth and surprisingly pleasant ride over some pretty rugged intellectual terrain, it is because Pinker writes in the same breezy style that brightens his classroom lectures. He likes to quote Mae West ("Men like women with a past because they hope history will repeat itself") and Woody Allen ("I think people should mate for life, like pigeons or Catholics"), along with linguist Noam Chomsky, artificial-intelligence guru Marvin Minsky and, of course, Charles Darwin. Pinker has a showman's sense for knowing "when to hold his reader's attention with an illustration or a joke," observed University of Oxford zoologist Mark Ridley in the New York Times Book Review last week. "No other science writer makes me laugh so much."

How the Mind Works is stirring up an academic hornet's nest. The ideas that anchor Pinker's book--an artful blend of artificial intelligence and evolutionary psychology--strike many experts as glibly superficial. To Pinker's credit, he has worked hard to make explicit the sometimes tenuous connection between robots, computers and the evolution of the human psyche. Without the models developed by computer scientists, Pinker baldly states at one point, "it would be impossible to make sense of the evolution of the mind."

Sweeping pronouncements like that will strike many scientists who study the brain as puzzling, if not downright ludicrous. Neurobiologists, in particular, will find much to quibble with in How the Mind Works--which is not surprising, since Pinker comes at the subject from an entirely different perspective. The son of a traveling salesman, Pinker grew up in Montreal and attended McGill University, where he became fascinated with the psychology of perception and cognition. He received a Ph.D. from Harvard, then moved a few blocks down Massachusetts Avenue to M.I.T., linguist Chomsky's home base. Chomsky's seminal theory--that humans come into the world fully programmed for grammatical language--permeates Pinker's thinking. In his work, for example, Pinker tries to tease apart how the innate components of the language system interact with experience. "The past tense," he quips, "is my version of the geneticist's fruit fly. A verb is small, it's easy to recombine, and it's a fast breeder."

To call Pinker opinionated is an understatement. He declares, among other things, that there is no such thing as general intelligence. He dismisses as "neurobabble" the current fashion of dressing up fuzzy ideas about child rearing--like reading to babies--as somehow good for the developing brain. And he accuses intellectuals of pretending that evolution has nothing to do with "the fantastically complex design" of the human mind.

"But I can't think of anyone who thinks that," objects Patricia Churchland, a philosopher at the University of California, San Diego. "Of course, there is an evolutionary basis for the mind. The tricky part is to figure out how it all works."

Pinker has little patience with critics, particularly Harvard paleontologist Stephen Jay Gould, who accuses evolutionary psychologists in general (and presumably Pinker as well) of indulging a "penchant for narrow and often barren speculation" and "pure guesswork in the cocktail-party mode." Pinker has even less patience with those who would confuse an evolutionary explanation for how the human mind evolved with the idea that our fate is genetically predetermined. Genes, he says, "do not dictate what we should accept or how we should live."

In fact, Pinker, recently married for the second time, cheerfully confesses that he is so far voluntarily childless, thus flouting the evolutionary imperative to spread his own genes. "By Darwinian standards," he writes, "I am a horrible mistake. But I am happy to be that way, and if my genes don't like it, they can jump in the lake."