The Intelligence Test

Stephen Jay Gould and the Nature of Evolution

By Robert Wright

A review of Wonderful Life: The Burgess Shale and the Nature of History by Stephen Jay Gould. (Originally published in The New Republic, Jan. 29, 1990. Copyright 1990, Robert Wright. Robert Wright is the author of The Moral Animal: Evolutionary Psychology and Everyday Life.)

The acclaim for Stephen Jay Gould is just shy of being universal. He was among the first to win a MacArthur Foundation "genius" award. His lectures are renowned among Harvard undergraduates for their wit and erudition. His monthly column in Natural History has a devout following, and when his essays are anthologized (The Panda's Thumb, The Flamingo's Smile, etc.), the reviews are reliably favorable and the sales enduringly brisk. All told, Gould probably commands the largest and most enthusiastic readership of any evolutionist in this century. But within one small audience, the cheers are muted. A number of evolutionary biologists complain—to each other, or to journalists off the record—that Gould has warped the public perception of their field.

Of course, successful popularizers often incur the hostility of their less famous colleagues, and the complaints are fairly predictable: he oversimplifies in order to reach a large audience, he sacrifices precision for literary flourish. But in this case the indictment is a little meatier. For one thing, there is the occasional suggestion that Gould's political ideology has colored his view of evolution (a possibility that Gould himself, actually, was the first to raise). For another, there is the claim that Gould has self-servingly misrepresented the opinions of Charles Darwin—more than a misdemeanor for a person in Gould's line of work. And these issues are magnified by Gould's stature. He is, after all, America's evolutionist laureate. If he has been systematically misleading America about what evolution is and what it means, that amounts to a lot of intellectual damage.

Any good grounds for the charges against Gould should be visible in a book like Wonderful Life. The book—it is an original composition, not an anthology—is billed by Gould's publisher as his magnum opus, "a summation of two decades of his work in paleontology and the history of life." It recapitulates Gould's favorite themes, touches once again on the question of Darwin's rightful legacy, and revisits many issues that, academic as they may sound, have ideological import: the pace of evolution, the role that "chance" plays in it, and the direction, if any, in which evolution tends to move.

Gould's central goal in this book is to demolish once and for all the comfortable notion that the human species is Darwinianly ordained—that we, the only self-conscious animals, sit at the pinnacle of evolution, and that, indeed, the whole point of evolution may in some sense have been to reach this pinnacle. There is no ladder of evolution, Gould insists, no necessary path of rising biological complexity and sentience; the coming of self-conscious intelligence was not inexorable, or even very likely. Rather, our species exists by virtue of a long series of lucky evolutionary breaks. If you re-wound the tape of organic history and edited out any one of those breaks, all subsequent evolution would be radically altered. "Replay the tape a million times," he writes, "and I doubt that anything like Homo sapiens would ever evolve again."

This is an arresting thesis, but Gould never comes close to making the case for it. To be sure, he's right in saying that there's no simple "ladder" of evolution, and that there's nothing literally inexorable about the evolution of intelligence. But there is a plausible argument that the coming of self-conscious intelligence was nonetheless quite likely from the beginning, and Gould never succeeds in casting any doubt on it. Indeed, he never even confronts the argument straightforwardly—a fact that, given what this book is supposed to be about, is nothing short of weird.

To understand how Gould's thesis intersects with political ideology, and how centrally it figures in his whole conception of evolution, you have to understand how Darwinism was distorted during the late 19th and early 20th centuries for political and religious purposes. After the publication of The Origin of Species in 1859, those clergymen who didn't reject the theory of natural selection outright tried to reconcile it with their faith. One approach was to view evolution as divinely driven—as a long and slow, but steady and inexorable march up the hill of organic complexity and intelligence, toward an animal worthy of admission to heaven. This solution to the crisis of Christian confidence was nicely adaptable to the needs of those on the right who wanted to defend capitalism in its rawest, cruelest form. The result was social Darwinism: if evolution was God's will, then the survival of the fittest, with all the attendant suffering, must be morally justified in the name of progress; with people as well as other animals, it must be all right for some to starve while others thrive. Racism and imperialism found comparable comfort; any God who had designed natural selection, it was said, would surely agree that "inferior" nations and races deserve conquest and oppression. These religious and political forces—along, no doubt, with some honest incomprehension—reinforced the simplistic equation of natural selection with inevitable progress toward a preordained goal.

Though this "progressivist" view of evolution hasn't been common among biologists for many decades, Gould has spent a good part of his career combatting it. It is a recurring theme in his Natural History columns, and it is an intended victim of the much-publicized "theory of punctuated equilibrium," which Gould co-authored. The theory holds basically that evolution proceeds in jumps and starts and somewhat chaotically: species go for long periods with little or no change, and then "suddenly" (which in evolutionary terms can mean many thousands of years) they change dramatically, often splitting into two or more new species. And these transformations, Gould stresses, don't necessarily sustain any previous trajectory of development. The upshot is an evolution that's jerky and aimless—a process that doesn't proceed smoothly, much less smoothly toward anything.

It was the theory of punctuated equilibrium that got Gould accused of putting words in Darwin's mouth. Aided by obliging journalists, Gould billed the theory as a sharp departure from the "gradualist" view of evolution purportedly held by Darwin and his intellectual descendants. But, as Richard Dawkins showed in his essay "Puncturing punctuationism" (in The Blind Watchmaker), the main contours of this "radical" theory had long been accepted by people Gould calls gradualists, notably Darwin himself. Darwin's repeated emphasis on the "gradual" nature of evolution was only for the slower students—people who couldn't quite fathom how you get an organ as complex as, say, an eyeball through incremental change. Very, very slowly, he replied. But Darwin was fully aware that the rate of evolution varies wildly in response to changing conditions. As he himself put it, "The periods, during which species have undergone modification, though long as measured by years, have probably been short in comparison with the periods during which they retain the same form." This quotation doesn't match up too neatly with Gould's assertion in Natural History that Darwin believed evolutionary change to be "generally slow, steady, gradual, and continuous."

Certainly the theory of punctuated equilibrium has its genuine novelties. For example, though almost everyone concedes the importance of rapid bursts of evolution, Gould places unusual emphasis on them, and he insists on minimizing intermittent, slower forms of change. But by and large the theory's novelties haven't impressed top-flight biologists. Today punctuationism remains a fairly hot topic within paleontology, Gould's field, but within evolutionary biology it is considered by many to be little more than a curiosity.

What had attracted Gould to the theory of punctuated equilibrium? Back in the 1970s, when he unveiled the theory, he used to note that "my daddy raised me a Marxist" and talk about the natural affinity between punctuationism, with its emphasis on periodic revolutionary upheavals, and a Marxist view of history. Both, he has written, embody the "law of transformation of quantity into quality"— "when you heat up water it boils at a certain point . . . and, if you oppress the workers more and more, eventually this leads to revolution." Gould made viewing biology through Marxist lenses sound only fair; many biologists who emphasize more gradual evolution, he noted, have probably been subconsciously influenced by their ideology—by a belief in plodding social change that comes from within the system. Indeed, a Marxist slant on change, he seemed to feel, leaves less of a taint than an ameliorist slant. In 1978, speaking at a "Dialectics Workshop" at Harvard, Gould said that gradualism, "arising largely out of pervasive political bias," has been "a restraining dogma" in discouraging radical social change. But he characterized punctuationism "not as a dogma but as an alternate or pluralistic widening of the ways we look at change." Get the distinction?

Since becoming a well-known popular writer, Gould has been less vocal about his politics. He is no longer associated with Science for the People, the Cambridge-based activist group that he worked with during the late 1970s, notably in launching some rather nasty attacks on fellow Harvard faculty member E. O. Wilson, whose book, Sociobiology, Gould deemed to have right-wing tendencies. And in recent years, when asked whether he's a Marxist, Gould has replied that he doesn't like "labels." But in a sense the issue of Marxism, for all the muttering that Gould's more ardent detractors do about it, isn't that important. Quite aside from a Marxist view of historical change, one can see a separate attraction that any leftist—or any centrist, or, for that matter, any humane conservative—might feel toward a doctrine that promises to weaken the basis for social Darwinism. The question is whether scientists should succumb to such extrascientific attractions, and whether Gould does. Or, more realistically (given that scientists are only human), the question is how successful scientists can hope to be in resisting such temptations, and whether Gould seems to be making an earnest effort at resistance.

Gould, in any event, spends much of Wonderful Life indicting another scientist for failure to resist. The book's narrative drive lies mainly in Gould's claim that the story's chief antagonist—Charles D. Walcott, head of the Smithsonian Institution from 1907 to 1927—was steered into a huge, philosophically consequential, scientific blunder by his political and religious beliefs. Walcott's error was made in deciphering fossils from the Burgess Shale, a limestone quarry in British Columbia. The shale holds a rich record of life just after the "Cambrian explosion," the period around 600 million years ago when multicellular life, then in its infancy, exhibited a sudden (as these things go) profusion of diverse forms. The shale contains around 75,000 specimens of at least 140 species. They were tiny creatures, an inch or two long, that lived underwater.

Walcott discovered the fossils in 1909, and then produced a taxonomic classification of them that went essentially unchallenged until the 1970s, when a group of British researchers showed that he had been wrong. His mistake, Gould explains, was in "shoehorning" the fossils into pre-existing categories; Walcott assumed that these animals were ancestors of existing species, that they belonged somewhere on the family tree of modern life. They might belong near the base of a main branch, or even lower, near the bottom of the trunk, but they could be squeezed in somewhere.

It turns out, however, that they can't be. Apparently many didn't evolve into anything lasting and don't fit anywhere along the conventional lineage. Judging by the Burgess Shale, then, it looks as if many, perhaps most, of the branches on the tree of early life got lopped off. What's more, it wasn't through any fault of their own. The design of the doomed species wasn't grossly flawed, Gould says: no one could have predicted which would survive and which would fail. It seems that they just ran into bad luck—a sudden ecological twist for which their past evolution had ill prepared them. Thus, the moral of the story of the Burgess Shale, as told by Gould, is very much in keeping with the moral of the theory of punctuated equilibrium. Species are frequently eliminated by "lottery," he says, and these virtually random events can fundamentally redirect evolution. Once again, Gould finds evolution to be a chaotic, directionless process.

And once again, he attributes claims to the contrary—Walcott's in this case—to subconscious bias. Walcott was a politically conservative and religious man. And, though Gould never convincingly shows Walcott's politics affecting his science, the role of his religion seems clear. Walcott wrote of God as "revealing Himself through countless ages in the development of the earth as an abode for man and in the age-long inbreathing of life into its constituent matter, culminating in man with his spiritual nature and all his God-like power." So is it surprising, asks Gould, that Walcott should see all the Burgess creatures as fitting neatly into the evolutionary march toward humanity?

Gould's probably right: Walcott's religion may well have warped his judgment. But to grant that a belief in the inevitability of evolved intelligence encouraged a misreading of the Burgess Shale is not to concede that the correct reading belies such inevitability. Once Gould's morality play is over, his argument still hasn't been made. He keeps promising that his interpretation of the Burgess Shale will lead to a "radical view about the pathways of life and the nature of history," but it never does.

The radical change Gould thinks he's ushering in is a shift in the "iconography" of evolution. Not only, he says, should we quit thinking of evolution as a ladder, leading to a specific preordained end (which, actually, pretty much everyone in science quit doing a long time ago); we should quit thinking of evolution as a robust, well-rounded tree, with all branches steadily subdividing along the way to create more kinds of life, and each branch heading toward greater organic complexity. This icon—"the cone of increasing diversity," he calls it— seems to give too much comfort to any remaining progressivists for Gould's taste, and, he says, it is belied by the many broken branches found near the bottom of the tree in the Burgess Shale. Indeed, these dead branches, Gould suggests, represent such a breadth of morphological diversity (broader, perhaps, than the current array of marine invertebrates) that the image of a tree, with its unified trunk, breaks down entirely. "Life is a copiously branching bush, continually pruned by the grim reaper of extinction," he writes. And: "The history of life is a story of massive removal followed by differentiation within a few surviving stocks, not the conventional tale of steadily increasing excellence, complexity, and diversity."

Bush, tree, cone—what's the difference? Not as much as Gould thinks. Granted, the Burgess Shale suggests that most of the branches at the bottom of the bush/tree of life never got very far. Gould's point, it seems, is that those doomed branches—broken off, perhaps, by some bit of bad luck, such as a geological or climatic upheaval—could just as easily have been our branches; our ancestors could have lost the "lottery." Or— since these prunings take place at various levels of the bush/tree—our ancestors could have been erased well after the Cambrian, perhaps even recently. And then where would we be?

Nowhere, obviously. But that's not news. Few biologists would deny that any number of chancy events could have altered evolution, perhaps so dramatically that nothing human—you know, five or six feet tall, hair under the arms, toe-nails—would have evolved. The real question is: Would any form of highly intelligent life have evolved if humans hadn't? Did the basic laws of natural selection make it highly probable that eventually some organism would have become conscious of itself, and even of the process that created it? Is great intelligence, generically speaking, inherent—or, at least virtually inherent—in evolution? For most of the book, Gould purports to be interested in that question. Yet he studiously avoids tackling it head on.

Had he done so, he would have had to face a few basic facts about evolution that seem to make him uncomfortable. The first of these is that evolution does exhibit a tendency toward rising organic complexity (along, often, with a growth in the size of organisms). An irresistible impetus? No. But a tendency? Definitely. All species have grown more complex through time; otherwise, they wouldn't be where they are today. True, a few species (some internal parasites, for example) have done some back-sliding, and become slightly less complex through evolution. And many others go long periods of time, conceivably forever, without growing more complex. And, obviously, some large and complex species die out. But to the extent that organic complexity within a particular lineage changes through natural selection, the change is almost always upward. And on the cutting edge of complexity—among the most complex (and often largest) animals in a particular group—there is very often change.

Whether you view evolution as a bush or a tree, you have to admit that its branches head generally upward.

And the reason isn't some immaterial elan vital, or anything mystical or supernatural, but rather the concrete advantages often conferred on an organism by greater complexity (the efficient division of cellular labor, for example) and greater size (which sometimes, in turn, dictates greater structural complexity). You don't have to see divine guidance in evolution to see some general patterns in it.

A companion basic fact about evolution—which Gould also prefers not to acknowledge—is that the complexity of organic information processing (in brains, notably) also tends to grow. For reasons now fairly well understood, the processing of information is fundamental to life. Even bacteria, which sit squarely at the bottom of the evolutionary tree (OK, OK, bush), absorb and process data about their environment in order to adjust to it. And once an organism is processing information, there are advantages to be gained by processing it more voluminously and complexly—greater flexibility in coping with threats, in finding food, etc. As with the growth of complexity, the evolutionary "pressure" toward greater intelligence is not irresistible. There are many reasons that many species don't get smarter with time. Maybe the species has a nice, comfortable niche already; maybe the niche "above" is occupied; maybe the needed genetic mutation just doesn't happen. Still, when the complexity of a species' information processing changes through evolution, the change is almost always upward. Across the mammalian class broadly—not just among us primates— evolution has been raising the brain-to-body ratio for a long time now.

A third basic fact about evolution is its tremendous inventiveness. As the mammoth diversity of organic form and behavior on this planet suggests, natural selection has quite a knack for "sensing" empty niches (or, strictly speaking, stumbling onto them blindly) and filling them. Thus evolution should tend not merely to create bigger, more complex, and smarter animals, but to apply this complexity and intelligence in a wide variety of ways.

I doubt Gould would admit it, but all three of these basic facts about evolution are beautifully borne out by the Burgess Shale. If we judge by the shale's fossils, as Gould wants us to, it appears that the diverse array of Cambrian multi-cellular life was ravaged by "decimation," as he calls it, and that such decimation has periodically revisited the bush of life. Yet even faced with these setbacks, evolution has flourished, generating a wide range of simple and, increasingly, complex organisms, and filling just about every obvious large-scale niche: there is life in water, life on land, life underground, life in the trees, life in the air (wings have been invented several different times by natural selection); there is multimedia information gathering and sharing—via sound, physical contact, smell, taste, and light (eyes have been invented dozens of times). Gould's choice of words in insisting that life is a bush continually "pruned" by extinction is more apt than he realizes: you cut off one branch, and the other branches flourish all the more, rapidly filling some of the ecological space that the missing branch otherwise would have occupied.

In short, what Gould seems to consider central to his argument is more or less irrelevant to it. He can talk all he wants (and he does) about the role of "contingency" in natural history, about how some quirky ecological circumstance can send the branches of evolution zigzagging in odd directions, or even snip them off. (The book's title comes from the movie It's a Wonderful Life, in which a handful of Jimmy Stewart's decisions turn out to have redirected the evolution of an entire town.) But if the overall direction of the bush's branches, after all the zigzagging and dying out are done, is toward complexity and intelligence, then how much bearing does this "contingency" have on the thesis that the evolution of highly intelligent life was highly unlikely?

Gould can respond to this question in either macro- or micro- terms. He can either (a) attack one or more of the above three generalizations about evolution, or claim they don't really add up to the image of a bush growing generally upward, or perhaps contend that there is some fundamental limit on the bush's likely growth; or (b) go down the evolutionary bush and show how at critical junctures the flow of life might well have—indeed, probably would have—veered away from the evolution of intelligence had circumstances been slightly different. Remarkably, Gould goes the whole book without doing (a), perhaps because addressing these three generalizations would require him first to utter them, which I gather he can't bring himself to do, so redolent are they—in his mind, at least— of the dreaded progressivism. But he does, in the book's last chapter, finally get around to (b): examining specific junctures of human evolution and arguing that evolution was actually quite unlikely to head, as it repeatedly did, in the direction of greater intelligence.

Look at our recent evolutionary history, says Gould. Note that even as our ancestors, early Homo sapiens, flourished, other pretenders to the throne—Neanderthals, Asian Homo erectus—fell by the wayside. Well, what if we, too, had shared their bad luck? Then there wouldn't be anything smarter than chimps.

Not so fast. Gould neglects to mention the distinct possibility that the evolutionary success of Homo sapiens was the source of the Neanderthal's demise. It sometimes happens that as a species flourishes, it displaces a species that occupies roughly the same niche; the second species either finds another niche or dies out. Once our ancestors began wielding tools deftly, engaging in long-term planning, and coordinating social endeavors (hunting, say), life probably became harder for other upright primates in the vicinity—especially if, as is quite possible, our ancestors were busy clubbing them to death and eating them. So if our little evolutionary twig had snapped, the Neanderthal twig, or some other similar twig, might well have gone on to extend the evolutionary envelope of intelligence.

Bizarrely, Gould dismisses the possibility that Neanderthals would have ever achieved great intelligence by noting that they, unlike Homo sapiens of their age, hadn't invented the calendar stick or the counting blade, and, judging by their caves, they "knew nothing of representational art." Those brutes! But of course, the same had once been true of Homo sapiens. That's the way evolution works: one day you're not so smart, and then, a few thousand generations later, you're pretty smart. What the Neanderthals did have was a proficiency with tools, and as Gould must surely know, this adds considerably to the evolutionary pressure favoring greater intelligence.

Long before Neanderthals, actually, the pressure for intelligence had been great. Even if all species of the genus Homo had perished, my strong hunch is that some other primate would have eventually taken up the torch. Consider chimps. They use rudimentary tools (twigs to collect and eat termites, stones to break open nuts); their survival can depend on fairly complex communication (vocal and otherwise); and their social dynamics establish a correlation between cleverness and reproductive success (a male's access to mates may be secured through subtle scheming involving the formation of convenient alliances and the undercutting of a rival's social status; a female's reproductive success depends in various ways on her judgment and cleverness). All these things bode well for the evolution of higher intelligence.

But you probably won't hear much about this from Gould. For these evolutionary pressures are manifested in slow, tediously incremental, but ultimately significant change—through the elimination (or failure to reproduce) of individuals within a species generation by generation, not through the sudden elimination of an entire species or the relatively sudden branching off of a new species. No environmental cataclysm is necessary (though one may help). And this sort of "gradualist" evolution Gould would rather minimize in favor of puntuationism. This emphasis is unfortunate—partly because it seems unwarranted by the evidence, but also for a quite different reason: often the logic behind the most subtle, least cataclysmic, forms of evolution is the most intellectually beautiful. It is a shame that America's foremost popularizer of Darwinism is ill-disposed to share a large part of evolution's elegance with the public.

If you somehow wiped out all the primates, I wouldn't put it past, say, wolves or lions—whose lineages have thus far grown in intelligence, after all—to have great-great-great etc. grandchildren who would play Pac-Man (or Pac-Wolf). But suppose all mammals had died out. Gould speculates that if the dinosaurs hadn't run into some bad luck and perished, then mammals, which at that time were just small furry nuisances from the dinosaur's point of view, might never have made anything of themselves.

Maybe so. Maybe not. There's simply no way of knowing. But, anyway, who's to say that the dinosaurs themselves wouldn't have someday attained great intelligence? It now looks as though some of the bigger-brained dinosaurs could stand upright and use grasping forepaws, and that some dinosaurs may have been at least quasi-warm-blooded and cared for their young. But Gould smoothly dismisses the dinosaur scenario. "Since the dinosaurs were not moving toward markedly larger brains, and since such a prospect may lie outside the capabilities of reptilian design, we must assume that consciousness would not have evolved on our planet if a cosmic catastrophe had not claimed the dinosaurs as victims [emphasis added]" What a strange thing for a co-author of the theory of punctuated equilibrium to say! If evolution passes through long periods of stasis, and then witnesses dramatic change overnight, what is the point of extrapolating from gradual trends? How could a punctuationist ever say with confidence that an animal was not "moving toward" anything?

But the strangest of Gould's logical inconsistencies occurs in the final paragraphs of the book, where he makes the case that not just mammals but all vertebrates were just plain lucky to escape the dustheap of history. He notes that among the fossils of the Burgess shale is one called Pikaia. And Pikaia is a member of the phylum Chordata, which includes vertebrates. Is Pikaia, then, the missing link, whose survival is the reason that all vertebrates, including us, exist? Well, actually, no, Gould admits. "I do not, of course, claim that Pikaia itself is the actual ancestor of vertebrates, nor would I be foolish enough to state that all opportunity for a chordate future resided with Pikaia in the Middle Cambrian . . ."

Yet in the very next paragraph Gould states exactly that: "Wind the tape of life back to Burgess times, and let it play again. If Pikaia does not survive in the replay, we are wiped out of future history—all of us, from shark to robin to orangutan." And again, in the book's final paragraph: "And so, if you wish to ask the question of the ages—why do humans exist?—a major part of the answer, touching those aspects of the issue that science can treat at all, must be: because Pikaia survived the Burgess decimation."

I have read these passages five times now, and I still can't see a way to close this immense discrepancy. Did Gould just mean to be metaphorical in the last two paragraphs? If so, dropping a hint to that effect would have been a nice touch. More likely is that here Gould has unconsciously succumbed to the tension that is tangible in much of his writing: between maintaining his scientific credentials and wowing a lay audience. He wants to make sweeping, dramatic statements that will leave readers agog, yet he can't be seen by his peers making the facile assumptions that such drama often requires.

Gould has previously pushed his luck in trying to have it both ways, and has paid the price; among some evolutionary biologists, his reputation has suffered as a result of the caricature of Darwin's thinking he invoked to convince lay readers that punctuationism was radically new. This time, it seems, he has gone further. He has sent plainly contradictory messages to his two cherished audiences. And, inadvisedly, he has sent them in consecutive paragraphs.

In a sense, though, this is not the most abject surrender he makes in this book to the pressure of trying to please all the people all the time. That comes when, in the penultimate chapter, he suddenly backtracks on what had until then seemed to be one of his central claims. For most of the book, the reader has been led to believe that Gould is talking about the predictability not merely of human intelligence, but of any sort of higher intelligence. At the outset, in the most explicit formulation of his thesis, Gould couches it in terms of human evolution per se, but he thereafter goes on to talk repeatedly in terms of the "eventual origin of self-conscious intelligence," or the "predictable evolution of consciousness." Then, 30 pages from the end, he seems to realize that, however much this bolder version of his thesis may dazzle the average book buyer, he hasn't come close to making an academically respectable argument for it. So, in a last-minute disclaimer that is virtually muttered under his breath, he admits, basically, that he was just kidding.

The admission comes as he is talking about the boundary between the inevitable and the contingent—between those features of life that follow from the basic dynamics of evolution, and those that are the result of happenstance. The evolution of human life, he is confident, falls below the boundary, in the realm of the contingent. But, he adds, nonchalantly: "Whether the evolutionary origin of self-conscious intelligence in any form lies above or below the boundary, I simply do not know [emphasis added]. All we can say is that our planet has never come close a second time."

Then what was the point of writing this book? As I've said, virtually everyone concedes that a well-timed drought or some other evolutionary obstacle might have blocked our species' particular route to intelligence. That hasn't been an issue since the looniest, most flagrantly teleological views of evolution were put to rest. 'l'he only remaining question (and the only philosophically important question, really) is whether evolution would have eventually followed alternative routes to intelligence anyway.

Even as Gould shrinks from addressing this prospect head on, note how facilely he tries to minimize it: "All we can say is that our planet has never come close a second time." This is a fairly disingenuous thing for a paleontologist to say. In paleontological time, the 250,000 years of Homo sapiens' existence is little more than a few seconds. It would be eerie indeed if two widely divergent paths to intelligence, having taken so long to get there, arrived at the same moment. Have some patience, for God's sake. The journey from a single-celled animal to a bird, to a dog, to a bear, to a chimp, took a few hundred million years. By Gould's own estimate, the Earth will probably be around another five billion years. Doesn't that leave time for a bit more action on the evolutionary front?

You could probably explain a certain number of the inconsistencies and intellectual evasions in this book by reference to time-honored popularizer's temptations: Gould likes high drama and literary flourish, and he likes to be seen brilliantly demolishing whole pillars of Western thought. So it's natural that he should make the pillars seem more important, and the demolitions more brilliant, than they really are. (In Wonderful Life he makes the pillar in question look important not only by acting as if progressivism is still a force in science, but by arguing—ineffectually—that Darwin himself harbored progressivist sentiments.) But it's a little suspicious how often these pillars seem to be supporting an ideology Gould finds abhorrent. And if you go through his past writing, you'll see this happen repeatedly: there is a bad doctrine, usually associated with a bad guy (Charles Walcott is only the latest), and then there's Stephen Jay Gould, the good guy holding up the good doctrine.

Again, it isn't Gould's cause that is objectionable; none of us wants Darwinism misused to justify racial oppression, or income inequality, or anything else. But trying to snuff out reactionary politics by distorting evolution simply won't work. Gould can keep pretending, as he did with punctuated equilibrium and has now done with the Burgess Shale, to have a view of evolution that's so radical as to single-handedly undermine social Darwinism. But eventually the truth will come out: his view is less radical and original than it's billed as being, and some of its most original parts are its shakiest. So we're back to mainstream Darwinism, and to the initial question: Is there any logical basis for reading right-wing messages into conventional ideas about how evolution works?

Fortunately, the answer is no. In fact, there is no basis for reading any political messages into the dynamics of evolution, or, even more generally, for extracting any ideals from the workings of nature. And there's no real controversy on this point. The illegitimacy of inferring "ought" from "is" has been a matter of virtual consensus in both science and philosophy for the better part of this century. It should go without saying that inferring "is" from "ought" is also illegitimate.

(Originally published in The New Republic, Jan. 29, 1990. Copyright 1990, Robert Wright. Robert Wright is the author of The Moral Animal: Evolutionary Psychology and Everyday Life.)