What do Stalin, modern architecture, radical feminism, and most parenting experts have in common? They are all products of the false belief that we are born with empty minds, a tabula rasa. Or so says Steven Pinker in his new book, The Blank Slate. If the aim of science is to explain apparently unrelated phenomena via a single elegant theory, Pinker is obviously onto something big. Any theory that can explain the origins of the Five Year Plan and Le Corbusier must be reckoned with.
Pinker, Peter de Florez Professor of Psychology in the Department of Brain and Cognitive Sciences at MIT, is an accomplished psycholinguist. But he is best known as a science popularizer. His previous popular books, including The Language Instinct (1994) and How the Mind Works (1997), were huge commercial and critical successes. While The Language Instinct concentrated on the Chomskyan revolution and the now overwhelming evidence of an inborn mental organ underlying grammar, How the Mind Works cast a broader net, reviewing a good deal of cognitive science and a smattering of neurobiology. In his latest book, Pinker steps back yet further and reassesses the interminable debate over nature vs. nurture. Are personality, intelligence, gender, and the moral sense in the genes or are they the stuff of culture? In view of his previous work, you probably won’t be surprised to learn that Pinker thinks much of what makes you you resides in your genome.
Pinker takes aim at three targets in his book. He calls them the Blank Slate (the notion that the mind has no inherent structure), the Noble Savage (the notion that man is born innocent and is corrupted by society), and the Ghost in the Machine (the notion that mind differs from matter). These correspond, at least loosely, to the philosophical traditions of empiricism, Romanticism, and dualism, respectively. Pinker considers all three traditions because he believes they are typically found together. While this seems doubtful (Marxists subscribe to the Blank Slate and the Noble Savage but reject the Ghost in the Machine, while Catholics do the opposite), it doesn’t much matter. Pinker ends up attacking what he takes to be the errors of the Blank Slate almost exclusively and the other two targets mostly disappear.
The Blank Slate is a distinctly Western idea of fairly recent origin. It was first articulated in 1690 by John Locke in An Essay Concerning Human Understanding. Though Locke offered the tabula rasa as an epistemological theory—knowledge comes from experience—it had, and has, obvious social implications. As Pinker explains:
The Blank Slate has also served as a sacred scripture for political and ethical beliefs. According to the doctrine, any differences we see among races, ethnic groups, sexes, and individuals come not from differences in their innate constitution but from differences in their experiences. Change the experiences—by reforming parenting, education, the media, and social rewards—and you can change the person. Underachievement, poverty, and antisocial behavior can be ameliorated; indeed, it is irresponsible not to do so.
Despite the warm feelings such talk evokes in most of us, Pinker says we’ve got it all wrong. In fact we have it wrong in two ways. The first is that the Blank Slate is simply false. The “new sciences of human nature”—combining cognitive science, neuroscience, genetics, and evolution—strongly suggest that our minds are partly “hardwired” at birth. Pinker spends much of his book arguing that this hardwiring likely underlies many human universals—forms of behavior and mental structures shared by all peoples in all cultures, e.g., baby talk and incest avoidance. But it also seems likely that such hardwiring underlies some differences among people. Though Pinker emphasizes that he’s not a fanatic—he does not deny an important role for environment in who we become—he believes that differences in traits such as those that contribute to personality are at least partly due to differences in genes. He also argues that male and female minds differ biologically. Male minds are, for example, predisposed to greater aggression and sexual promiscuity. Male and female minds also appear to have different cognitive strengths: boy brains are better at mentally rotating 3-D objects, for example, while girl brains are better at recalling words. And these differences in brain functioning are, Pinker argues, likely genetic.
The second way Pinker says we have it all wrong is in thinking that the Blank Slate is a moral good. It is not. Pinker devotes much of the second half of his book to the moral and political implications of the debate between nature and nurture. He concludes that Blank Slate ideology is pernicious nonsense that “distorts our science and scholarship, our public discourse, and our day-to-day lives.” Locke’s ostensibly innocent tabula rasa is in fact an “anti-life, anti-human theoretical abstraction that denies our common humanity, our inherent interests, and our individual preferences.” Not surprisingly Pinker thinks this monstrous doctrine has given rise to a host of sins, including those listed at the start of this review.
At the same time, Pinker tells us, denial of the Blank Slate does not lead to moral catastrophe. Despite left-wing propaganda to the contrary, the “existence of human nature is not a reactionary doctrine that dooms us to eternal oppression, violence, and greed” or that requires us to “abandon feminism, or to accept current levels of inequality or violence.” Devoting a chapter each to gender, inequality, child-rearing, and violence, Pinker concludes that you can be both a hereditarian and a decent human being. The reason, he says, is simple: biology is not morality. And once this fact sinks in, we see that we can both recognize and condemn any dark, biological side to humanity. The new sciences of human nature are morally neutral.
The most impressive thing about The Blank Slate has less to do with its thesis than with how it’s delivered. Pinker’s prose remains as brisk and witty as ever and he’s able to convey difficult technical matters with a minimum of jargon. He also scores a number of direct intellectual hits and is perhaps at his best when exposing the undeniable excesses of Blank Slate enthusiasts. His accounts of behaviorists who have maintained that sexual desire is learned, and fringe feminists who have claimed that castration can’t stop rape since it’s a crime of violence, are devastating.
This is not to say the book is without problems. Some of these amount to mere annoyances, like Pinker’s tendency to talk out of both sides of his mouth. He tells us early on, for instance, that there is good evidence that “sexual orientation” is heritable but later on that “no one knows why some boys become gay.” Similarly, “the idea that nature and nurture interact to shape some part of the mind might turn out to be wrong” but “the nature-nurture debate, as it has been played out for millennia, really is over, or ought to be.”
But the most serious problem with Pinker’s book is that he makes things too easy on himself. Pinker has a habit of making things seem simpler than they are and of doing so in a way that just happens to make his claims more secure and his conclusions more inescapable than they really are. This is not to say that the direction he moves in is wrong—a wholly Blank Slate is untenable and he is right to say so—but it is to say that there are good reasons for not going as far as he’d like you to. Pinker’s tendency to make things too easy leads him into three kinds of problems. One is scientific, one historical, and one ethical.
Pinker’s scientific problems begin when he builds—and then torches—a straw man. For the Blank Slate he assails is something few thinking people believe in. Of course we’re organisms, of course we evolved, and of course this is as true for the brains between our ears as for our ears. This may have been scandalous stuff in 1871 when Darwin published The Descent of Man but it is not now. The result is that it’s easy for Pinker to appear on the side of the angels. He assails those intellectuals who believed that genes cannot shape brains or who insisted that our minds are animated by little ghosts who lurk in the interstices of our neurons. Whether such intellectuals still exist seems a lesser concern.
But there’s more going on than this. After Pinker’s relentless parodying of the Blank Slate, the reader, sensibly enough, wants nothing of it. The problem is that it’s unclear what Pinker is proposing instead, at least early on. And that’s because Pinker has a frustrating way of not distinguishing between weak and strong versions of his claims.
Take this statement: “History and culture, then, can be grounded in psychology, which can be grounded in computation, neuroscience, genetics, and evolution.” This is one of Pinker’s big conclusions. But it might mean several very different things. One is that culture is made from minds which are made from neurons which are made by genes. This is undeniable. Another is that culture is made from minds that have been hardwired by genes to have certain contents—to think certain thoughts, say—a stronger claim. Yet another is that culture is made from minds that have been shaped by natural selection to think certain thoughts because those thoughts maximized the number of children ancestral thinkers had on the savanna and so gave them an evolutionary advantage over those who did not think such thoughts. This claim is stronger still.
This ambiguity comes in handy. If Pinker senses doubt about a strong version of his claims, he can adroitly slip into a defense of a weak version. Are you feeling uneasy about the notion that culture can be reduced to neurons and genes? But surely you admit that “culture relies on neural circuitry that accomplishes the feat we call learning”? Surely you acknowledge that “culture could not exist without mental faculties that allow humans to create and learn.” Well, of course you do.
If that’s the claim of the new sciences of human nature, we can all agree they’ve been a big (if banal) success. But that’s not their claim. The new sciences of human nature go much further. And so does Pinker.
As his book progresses it becomes clear that Pinker is committed to a particular and strong strain of psychology. It’s not just that minds emerge from neurons (no Ghost in the Machine). And it’s not just that some features of minds—grammar, say—are genetically hardwired (no Blank Slate). It’s that we can “reverse engineer” the mind and the mental modules that allegedly make it up. (A mental module is a neurological “program” that performs a specific function. The grammar module, for instance, does a different job from the visual surface-perception module, which in turn does a different job from the “cheater-detection” module, as described below.) Just as an engineer who sees a spark plug for the first time could infer its purpose by studying an engine, so we as psychologists can infer the evolutionary “purpose” of behaviors and mental modules by studying when they come into play in daily life and how they increase reproductive success. We can, in other words, discern the adaptive reasons why our minds do what they do. In short Pinker champions a Darwinian psychology of human beings. But the proposition that we can build a Darwinian science of mind is distinct from—and more ambitious than—the proposition that the slate isn’t blank.
Pinker’s fondness for “evolutionary psychology” will come as no surprise to those who remember How the Mind Works. But it is surprising to see how extreme he has become. Pinker seems never to have met an adaptive tale he doesn’t like. Rape is likely an adaptive strategy pursued by low-status males who are “alienated from a community” and “unable to win the consent of women.” A gene that predisposes such males to rape will spread. Neonaticide, the killing of newborns, reflects the evolutionary calculus of conflict between parent and offspring. A gene that predisposes mothers to kill newborns when times are tough, saving resources for reproduction when times are better, will also spread. Weak armies may march suicidally into bat-tle because of natural selection. Evolution favors bluffing in confrontations (an opponent might, after all, back down) which in turn favors some self-deception (you’re a better liar if you believe your own lie). Psychopaths may walk among us because of an esoteric evolutionary phenomenon called frequency-dependent selection. A gene that predisposes one to lie, cheat, and manipulate may enjoy an advantage when rare (since most people are trusting and thus vulnerable) but not when common. And so it goes. In places Pinker simply seems credulous. When discussing twins who were separated at birth, for example, he is enthusiastic about those who “both grew up to be captains of their volunteer fire departments” or who “both twirled their necklaces when answering questions.”
Now there’s no reason to think that Pinker’s psychology-as-adaptive-tale is inherently hopeless. A Darwinian approach to mind may be no more impossible than a Darwinian approach to mammaries, and an evolutionary psychology might well reveal something about human nature. Indeed any or all of Pinker’s adaptive tales could be true. But there are grounds for worry. One is that, despite Pinker’s confident tone, the evidence for his stories varies wildly and some of his tales are sheer speculation. There is, for example, little or no evidence that either human neonaticide or self-deception is genetic. These cases are in fact symptomatic of a serious problem with evolutionary psychology: its research program shows a curious tendency to invert itself. You might think that convincing evidence that a particular form of behavior is inherited usually leads to attempts to explain how and why it evolved. But often what happens is the reverse: the fact that we can conceive of an adaptive tale about why a behavior should evolve becomes the chief reason for suspecting it’s genetic. Why, after all, does Pinker think human neonaticide might be genetic? Where are the twin studies, chromosome locations, and DNA sequences supporting such a claim? The answer is we don’t have any.
What we do have is a story—there’s an undeniable Darwinian logic underlying the murder of newborns in certain circumstances. And so the inversion occurs: the evolutionary story rings true; but evolution requires genes; therefore, it’s genetic. This move is so easy and so seductive that evolutionary psychologists sometimes forget a hard truth: a Darwinian story is not Mendelian evidence. A Darwinian story is a story. And the accumulation of such stories has an important consequence. The slate may seem to get less and less blank in part because evolutionary psychologists keep scribbling more and more tales on it.
An evolutionary psychologist might counter that the fact that a behavior conforms so closely to what’s expected of an adaptive one is evidence that it’s a bona fide biological adaptation. And here we arrive at another problem. For the same logic that makes a behavior evolutionarily advantageous might also make it “economically” advantageous. In other words, sometimes it just pays to behave in a certain way, and an organism with a big-enough brain reasons this out, while evolved instincts and specialized mental modules are beside the point.
Take cooperation. Evolutionary psychologists are keen on the idea that people are genetically predisposed to cooperate in certain circumstances but not in others: our genes have shaped our emotions, for instance, such that we feel gratitude to those who work with us but react angrily to cheats and freeloaders; moreover our brains allegedly come equipped with a “cheater-detection module” that grants us special facility in spotting cheats and rule-breakers. (In fact, the neural structures underlying such hypothesized modules are usually completely unknown.) Though all of this could be true, it seems entirely possible that we, with our prodigious brains, just figure out (or know from long cultural experience) that it pays to work together under certain circumstances. The point is that when evolutionary and economic considerations yield the same prediction, conformity to Darwinian predictions cannot be taken as decisive.
Some of Pinker’s adaptive tales also give short shrift to another possibility: a behavior might be genetic but not adaptive. If being a psychopath, for example, does prove to be genetic (the evidence is suggestive) it doesn’t follow that one must embrace baroque tales about exotic forms of natural selection. Maybe many psychopaths carry a deleterious mutation. Maybe, in other words, not being a psychopath is a good thing, just as you’d guess if you were innocent of evolutionary psychology.1
In sum, evolutionary psychology suffers a methodological problem: it is at times surprisingly unrigorous. Too often, data are skimpy, alternative hypotheses are neglected, and the entire enterprise threatens to slip into undisciplined storytelling. (One of the worst examples comes from Pinker himself. His popular piece on two cases of middle-class neonaticide is a nearly data-free account that comes perilously close to parody.2 ) Concerns about rigor are surely the leading worry about evolutionary psychology among working biologists. Ask a molecular geneticist who’s skeptical of Darwinian psychology to explain why. You won’t hear that the slate is blank; you’ll hear about “soft science.” In the end, evolutionary psychology wants to have it both ways. It longs after the prestige of hard science but hopes to be held to a lower standard of rigor than, say, molecular biology.
The important distinction we’re left with is the weak vs. strong one that Pinker blurs. One can admit that the slate isn’t blank without buying Darwinian psychology. One can say no to Locke without saying yes to Pinker. And note that this isn’t a mere formal possibility, a position no one actually takes. The linguist Noam Chomsky and the philosopher Jerry Fodor are, for instance, strongly committed mental nativists; yet both have profound reservations about Darwinian psychology. And some evolutionary biologists—even those who are enthusiastic about mental nativism—have worried aloud about evolutionary psychology’s modus operandi.3 Sharing their worries is not symptomatic of scientific illiteracy.
The second problem with Pinker’s book is historical. He misrepresents the objections of early opponents to Darwinian psychology. Darwinian approaches to mind have come in two varieties: evolutionary psychology and its precursor sociobiology. Pinker sees red (or, as we’ll see, Red) when meeting criticism of either and the most incendiary parts of his book are spent excoriating those who dared question sociobiology. The main target of his wrath is the radical science movement that sprung up in the wake of E.O. Wilson’s 1975 book Sociobiology. This in itself is somewhat odd as the radical science movement has been dead for as long as I can remember. Indeed I doubt most of Pinker’s readers know such a movement existed, much less have lost sleep over the threat it posed to God and country. But most readers likely have heard of those once associated with the movement—the geneticist Richard Lewontin and the late paleontologist Stephen Jay Gould, among others—and that seems grounds enough for Pinker to launch his crusade. He devotes most of two chapters to denouncing Lewontin and his associates, who, we are told, were “politically motivated” and responsible for “twenty-five years of pointless attacks.” By the end the naive reader has likely concluded that sociobiology’s critics were radical extremists hellbent on discrediting a Darwinian science of mind because it jeopardized their Maoist program of social engineering.
The main problem with this Red Scare argument isn’t that it’s unnecessarily vicious (though it is). The main problem is that the reader never hears Lewontin et al.’s real objections. Instead he is fed a simplistic line that maintains that sociobiology’s critics believed that next to nothing is in the genes. Now it’s true that sociobiology’s opponents thought that far less of human behavior is genetic than does Pinker. But it’s not true that this was their only—or even most important—criticism. Several of the objections of Lewontin and his colleagues to sociobiology assumed that mental traits and behaviors are in fact genetic. Here are two:
(1) The slate might not be blank, but it’s unclear if natural selection did the writing. Lewontin stressed that there are “many alternative evolutionary forces besides direct adaptation for establishment of characters.”4 Indeed Gould and Lewontin’s famous “spandrels” argument assumes that a trait is part of our biological heritage but is not the direct product of natural selection; instead it reflects an inevitable consequence of how organisms are built, just as spandrels, the triangular spaces between arches often found in ecclesiastical architecture, are an inevitable byproduct of placing a frame on arches. (See illustration on this page.) Gould made it clear that he thought this argument applies to many biological structures, including the human mind:
Snails build their shells by winding a tube around an axis of coiling. This geometric process leaves an empty cylindrical space, called an umbilicus, along the axis. A few species of snails use the umbilicus as a brooding chamber for storing eggs. But the umbilicus arose as a nonadaptive spandrel, not as an adaptation for reproduction. The overwhelming majority of snails do not use their umbilici for brooding, or for much of anything.
If any organ is, prima facie, replete with spandrels, the human brain must be our finest candidate—thus making adaptationism a particularly dubious approach to human behavior.5
Though spandrels represent Gould and Lewontin’s best-known objection to adaptationism generally and to sociobiology in particular, Pinker doesn’t say a word about them.
(2) Though a behavior may be adaptive, it might not be optimal, i.e., the best possible solution to a “problem” posed by the environment. The point is that natural selection merely makes things better; it does not guarantee that, out of several possible improvements, the best will be chosen. Indeed it is a mathematical fact that if several beneficial mutations are available, selection will often choose one that is not the best.6 Moreover, while sociobiologists typically look at a single trait, selection doesn’t. Selection only “sees”—and improves—overall fitness. Because of trade-offs among traits it’s possible that no trait is currently optimal. All of this is important since an entire empirical approach to sociobiology rested on the assumption that behaviors are optimal.
It seems clear why Pinker ignores these objections. It is, after all, easier to ridicule sociobiology’s critics by portraying them as politically unhinged than by engaging their actual arguments. It’s easier to win a debate if the audience can’t hear what the other side says. But while sociobiology’s critics were more sensible than Pinker lets on, we can still ask: Did they sometimes go too far? The answer is surely yes. Some of their claims were too extreme and some of their arguments haven’t aged well. But, despite Pinker’s enthusiasm, the same can of course be said of the early sociobiologists. It would, after all, be trivially easy to ridicule sociobiology by presenting only its most extravagant or dubious claims. Just look, for instance, at Wilson’s On Human Nature (1978) with its bizarre suggestion (among others) that sociobiology will reshape the humanities. No matter who you think won the sociobiology wars, you won’t find a balanced history of them in The Blank Slate.
The third problem with Pinker’s book involves ethics. The ultimate point of his argument is that the new sciences of human nature pose no threat to decency. We merely have to “distinguish biological facts from human values.” Is murderous rage in our genes? No problem. We can still condemn it. Is rape “a feature of human nature”? Also not a problem. For it “is inherent to our value system that the interests of women should not be subordinated to those of men.” No matter what our genes say, a liberal ethic is always there to Just Say No. No matter what the truth about human nature, we needn’t condone murder, rape, selfishness, or greed. And it’s true, we needn’t. But Pinker barely notices that the morality that’s always there to save the day—the one he glibly invokes to dispel the menace of evolutionary psychology—is itself a legacy of the despised Blank Slate.
Why do we believe all people have a right to something like life, liberty, and the pursuit of happiness? Why do we deny the divine rights of kings? And why, despite the fact that many cultures grant men nearly unchecked control over women, do we believe “the interests of women should not be subordinated to those of men”? Surely much of the answer is that we are inheritors of a liberal tradition that springs from Locke and his fellow travelers, men who rejected the hereditarian claims of royalty and aristocracy and gave birth to Enlightenment ideology. (Pinker does admit that one kind of feminism grew out of Enlightenment liberalism but that’s close to all we hear of his ideological debt.) In the end, Pinker fails to face a hard question: Is it really clear—if his hereditarian views had held from the time of Locke—that we would now be mouthing assuring words about how our value system demands that women not be subordinated to men? Is it really clear that the liberal ethic Pinker reflexively reaches for would be there?
While he never articulates this question, Pinker seems to sense it. The evidence is that he tries, in two steps, to evade it. Step one is to claim that our moral sense is itself a product of evolution. But this alone won’t do. Darwinism may well have endowed us with a crude morality, but this can’t explain why kings but not women once had rights, but now women but not kings do. Hence step two. Here we expand the moral circle out from kin, to tribe, to nation, and ultimately to all humanity. Though Pinker’s discussion of this expansion is complex, he thinks it also involves some evolution. For the moral circle mainly expands, he says, by the principle of reciprocal altruism, a sociobiological theory that shows how kindness can spread even among unrelated individuals. To Pinker, then, the moral circle is primarily “pushed outward by the expanding networks of reciprocity that make other human beings more valuable alive than dead.” This network is facilitated by “trade, cultural exchanges, and people-to-people activities.”
But this is silly. The notion that our moral circle expanded by reciprocity is in many cases ahistorical nonsense. Men had plenty of “people-to-people” interaction with women while condemning them to second-class citizenship. And slaveholding Southerners had more “cultural exchanges” and “people- to-people activities” with African-Americans than did abolitionist Northerners. At what point in history did our “networks of reciprocity” with women and slaves become sufficiently dense that the calculus of reciprocity demanded that we grant them the vote and freedom? The question is absurd. The fact is that for every case in which morality plausibly expanded by reciprocity there’s another in which it expanded by selfless moral reasoning, political or religious struggle, or even court rulings that forced a rule of conduct on those who initially opposed it. And it should be evident that a morality that bids us care for the severely handicapped cannot be explained by an expectation of reciprocity. So Pinker cannot, I think, minimize the debt he owes to Enlightenment ideology. The morality he uses to pacify evolutionary psychology is, to a good extent, a Blank Slate morality. Not bad for an “anti-life, anti-human theoretical abstraction.”
It is, I suppose, clear why Pinker doesn’t play up this fact. An awkward fact is, after all, most easily dealt with by not acknowledging it. But in the end the awkwardness shades into irony. For if the moral of Pinker’s story is that our robust liberal values can rise to the challenge of any Darwinian finding, it’s no longer clear who the hero of his story is—the hereditarian findings he so loudly champions or the Blank Slate liberal values that so deftly neutralize them.
For more on this possibility, see Chris Moore and Michael R. Rose, "Adaptive and Nonadaptive Explanations of Sociopathy," Behavioral and Brain Sciences, Vol. 18, No. 3 (September 1995), pp. 566–567.↩
"Why They Kill Their Newborns," The New York Times Magazine, November 2, 1997.↩
See Chomsky's Rules and Representations (Columbia University Press, 1980), pp. 99–100, and Fodor's In Critical Condition: Polemical Essays on Cognitive Science and the Philosophy of Mind (MIT Press, 1998) and The Mind Doesn't Work That Way (MIT Press, 2000), Chapter 5. See also D.S. Wilson, "Tasty Slice—But Where Is the Rest of the Pie?" Evolution and Human Behavior, Vol. 20 (1999), pp. 279–287, especially his critique of evolutionary psychological work on music as a sexual display.↩
R.C. Lewontin, "Sociobiology as an Adaptationist Program," Behavioral Science, Vol. 24, No. 1 (January 1979).↩
"Evolution: The Pleasures of Pluralism," The New York Review, June 26, 1997, p. 52; see also Stephen Jay Gould and Richard Lewontin, "The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme," Proceedings of the Royal Society of London, 1979. N.S. Newcombe, an authority on human spatial skills, recently suggested that the difference between male and female spatial abilities may be a spandrel, not an adaptive difference as Pinker suggests. ("Is Sociobiology Ready for Prime Time?" The Chronicle of Higher Education, December 13, 2002.)↩
H.A. Orr, "The Population Genetics of Adaptation: The Adaptation of DNA Sequences," Evolution, Vol. 56, No. 7 (July 2002), pp. 1317–1330.↩
For more on this possibility, see Chris Moore and Michael R. Rose, “Adaptive and Nonadaptive Explanations of Sociopathy,” Behavioral and Brain Sciences, Vol. 18, No. 3 (September 1995), pp. 566–567.↩
“Why They Kill Their Newborns,” The New York Times Magazine, November 2, 1997.↩
See Chomsky’s Rules and Representations (Columbia University Press, 1980), pp. 99–100, and Fodor’s In Critical Condition: Polemical Essays on Cognitive Science and the Philosophy of Mind (MIT Press, 1998) and The Mind Doesn’t Work That Way (MIT Press, 2000), Chapter 5. See also D.S. Wilson, “Tasty Slice—But Where Is the Rest of the Pie?” Evolution and Human Behavior, Vol. 20 (1999), pp. 279–287, especially his critique of evolutionary psychological work on music as a sexual display.↩
R.C. Lewontin, “Sociobiology as an Adaptationist Program,” Behavioral Science, Vol. 24, No. 1 (January 1979).↩
“Evolution: The Pleasures of Pluralism,” The New York Review, June 26, 1997, p. 52; see also Stephen Jay Gould and Richard Lewontin, “The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme,” Proceedings of the Royal Society of London, 1979. N.S. Newcombe, an authority on human spatial skills, recently suggested that the difference between male and female spatial abilities may be a spandrel, not an adaptive difference as Pinker suggests. (“Is Sociobiology Ready for Prime Time?” The Chronicle of Higher Education, December 13, 2002.)↩
H.A. Orr, “The Population Genetics of Adaptation: The Adaptation of DNA Sequences,” Evolution, Vol. 56, No. 7 (July 2002), pp. 1317–1330.↩