Disrobing the Naked Ape : Why Darwin’s theory still holds water : DARWIN’S DANGEROUS IDEA: Evolution and the Meanings of Life, <i> By Daniel C. Dennett (Simon & Schuster: $30; 688 pp.)</i>

Daniel Dennett cannot be accused of modesty. Anyone who writes a book about the human mind and calls it “Consciousness Explained,” as Dennett did with his previous tome, has a certain degree of (how shall I put it?) confidence in what he has to say. (After two millennia of effort, philosophers can at least seek a more respectable line of work, now that their central question has been solved.) Dennett enthusiasts will be happy to see that their hero is living up to their expectations in his latest publishing venture, whose subtitle is “Evolution and the Meanings of Life.” Phew!

Dennett set himself an enormous task: that of explaining why everything of importance in the world of nature--from clams to trees, from birds to humans, including the human mind and its products--are the outcome of Darwinian evolution. On the way he seeks to demolish various proclamations of the Harvard evolutionist Stephen Jay Gould, the MIT linguist Noam Chomsky and the Oxford mathematical physicist Roger Penrose, declaring that they are wrong, wrong in their views of evolution. Now that demands some immodesty. And, whether you conclude by the time you reach the end of this massive tome that Dennett makes his case or not, you have to admit that he is up to the challenge. Few mortals would be.

A separate question is whether many readers will be up to the challenge he sets as author, for this is not light fare. We are in the month of May, but when I turned the last page of Dennett’s offering I felt as I do at the end of Thanksgiving dinner: Everything I’ve consumed was really wonderful (except, why does Aunt Jemma always insist on putting marshmallows on the sweet potatoes?), but in the end I ate just too much of everything and I’m stuffed. “Darwin’s Dangerous Idea” is like that: sound concept, lucid development of ideas, combative intellectual jousting with opponents and a conclusion that demands your attention. There’s no question that Dennett is a fine thinker and an accomplished writer. But there is too much of it all--and, yes, there are a few marshmallows, too.

Dennett explains that he was propelled into writing the book by what he heard at a Cognitive Science Symposium at MIT, in 1989. Among the topics for discussion was the nature of language. “The level of hostility and ignorance about evolution that was unabashedly expressed by eminent cognitive scientists on that occasion shocked me,” he recalls. The reason for the hostility, Dennett believes is that “People ache to believe that we human beings are vastly different from all other species.” They are right, of course: Homo sapiens is the only species that has spoken language, highly developed consciousness and creativity, and culture. But they are not right, Dennett argues, in assuming--in truth, yearning--that these attributes arose by mechanisms different from those that gave rise to birds’ wings and the elephant’s trunk; namely, evolution by natural selection. Opposition to or critiques of strict Darwinian theory stem from the desire to wrap in some kind of inexplicable mystery all that we most cherish about ourselves, says Dennett.

The triumph of Darwin’s theory was explaining how in the world of nature organisms’ anatomy and behavior appear to suit them so aptly to their environments. Prior to Darwin, scholars viewed this fit as the outcome of divine design, the work of God’s hand. After Darwin, it was recognized as the result of adaptation through natural selection. Minute change by minute change--over long periods of geological time--organisms are shaped to the exigencies of their environment. This is basic stuff, of course, at least for the 53% of the American public that accepts evolutionary theory as a scientific explanation of life’s rich diversity. For Dennett, as for the Oxford biologist Richard Dawkins before him, it is everything.

And yet even among committed evolutionists there are questions raised and controversies bitterly fought over the strict interpretation of Darwinism. These critiques have usually been over the extent to which natural selection molds life as we see it, and the rate at which evolutionary change occurs. Gould was among the most vocal in suggesting that other factors--such as historical contingency and architectural constraint--intervenes in the possible outcomes of evolution by natural selection. Those in the trade will remember the late 1970s and 1980s as a time of great debate over these issues.

Dennett and Gould have replayed the battle of late, in various arenas, including the New York Review of Books, and much of the central part of “Darwin’s Dangerous Idea” is a replay of that replay, in detail. Gould, according to Dennett, was very influential in creating a myth of revolution in thinking, but only a myth. Nothing changed, really, he argues. Gould was simply “the boy who cried wolf.” There was no fire, says Dennett. Strict Darwinism remains intact. “It falls to me to dismantle the myth,” says Dennett. He is surely wrong here, because, again, those in the trade will remember the 1980s as a time when Darwinism was enriched by a wider perspective, one in fact that included sentiments espoused by Darwin that had been swamped by early 12th-Century enthusiasms of various kinds. Nevertheless, Dennett’s arguments for why he believes he’s right are well worth reading.

I sympathize with Dennett, however, in his puzzlement over why Gould and Noam Chomsky resolutely refuse to encompass human language within an evolutionary framework of natural selection. Gould has talked about language capacity arising as a secondary property of a brain that became large for other reasons. Chomsky’s claims are similar, though a little more mystical. But I question whether Dennett is correct in suggesting that Gould’s opinion reflects his “religious yearnings.” The imputation fits the author’s thesis, that rejection of strict Darwinian theory within the human realm stems from an urge to see Homo sapiens as special in the world of nature. But much of Gould’s writing rejects this view, too. There are many citations in the book that allow the reader to form a judgment.

When Dennett, in the final section of his book, moves into ethics and morality he strays into an arena in which bitter battles have been fought, again in the 1970s and 1980s, that of sociobiology. Are these cherished virtues of humanity the outcome of mindless Darwinian evolution? Or are they the special products of the special medium of our species, that of culture. Sociobiology argued for the former all those years ago, and indeed there has recently been a resurgence of such sentiments, under a different guise, that of evolutionary psychology. Dennett is probably right here in supporting the notion that Darwinism reaches deep into the very soul of our species, and he rejects the suggestion that we are somehow diminished by the idea. Even though life is not produced by a miracle, life’s products may seem miraculous to us, and, in the glow of understanding provided by Darwinian theory, command our respect.

Why is Darwin’s idea “dangerous”? Because, says Dennett, “In a single stroke, the idea of evolution by natural selection unifies the realm of life, meaning, and purpose with the realm of space and time, cause and effect, mechanism and physical law.” In other words, it cuts through every cherished notion we hold in life, from the simplest to the most complex, from the most abstract to the most personal. It is also, he admits, seductive, because it can explain everything, sometimes facilely so.

Dennett’s book is a bold work, which the reader may want to tackle like I plank to approach next Thanksgiving’s table: Don’t consume everything in one sitting, tempting though the multitude of offerings might be; be selective in what you take, even though Dennett’s tightly developed argument makes skimming chapters difficult. That way you will come away from “Darwin’s Dangerous Idea” sated and stimulated, whether or not you agree with its thesis. You can always go back for seconds.

And, if you’re listening Aunt Jemma, please leave out the marshmallows this year!