AFTERWORD TO THE 2016 EDITION

As I embarked on the publicity tour for The Blank Slate in September 2002, I knew my life would never be the same. The Blank Slate was the kind of book everyone calls “controversial,” and I was all too aware that writers who had advanced ideas similar to mine had been vilified, picketed, blacklisted, and sometimes assaulted. To be sure, I had stayed far away from the third rail of social science, race differences in personality and intelligence. But I was pressing such hot buttons as inequality, gender, violence, politics, and child-rearing, and as the taxi pulled up and the front door closed behind me I had every reason to fear that I was leaving a comfortable academic career for a world of pain.

Pain there would be—some vituperative reviews, a screaming match on a BBC radio show—but overall I came out of the experience unbowed and barely bloodied. The Blank Slate won three book prizes, was shortlisted for the Pulitzer and Aventis (now Royal Society Winton) prizes, found itself on a dozen best-of-the-year lists, and earned enough laudatory reviews to fill several pages of excerpts in the front matter of the paperback. (My favorite: “The Blank Slate is . . . unexpectedly bracing. It feels a bit like being burgled. You’re shocked, your things are gone, but you can’t help thinking about how you’re going to replace them.”). The thousands of letters, emails, and audience questions I received, even when critical, were almost entirely constructive.

Why did my fears (and colleagues’ warnings) that The Blank Slate would be career suicide turn out to be groundless? Perhaps it was that the book was about the intemperate reactions to earlier works that had defended the idea of human nature, so any intemperate reaction would only have proved the book’s main point.

Another reason The Blank Slate has not been seen as a dangerous book is that it explicitly disavowed the fatalism that many critics read into attempts to apply biological insight to human affairs. The view of human nature that is congenial to me made this disavowal easy. Though I am an advocate of evolutionary psychology and behavioral genetics, by training and in practice I am a cognitive scientist, with an appreciation of the infinite combinatorial powers of thought and language. These powers allow our species to think up, share, and test workarounds for our evolved limitations, workarounds such as education, science, and democratic government. The Blank Slate insisted that the cognitive faculties behind these institutions are as much a part of human nature as our uglier and more primitive drives. More generally, the popularity of the blank-slate doctrine originates in the fallacy that the existence of human nature would imply that people are insensitive to input from their environments. In fact an emphasis on human nature impels us to ask how people create and respond to their cultural environments, not whether they do.

Not only do I see no contradiction between acknowledging the dark side of human nature and figuring out how best to overcome it, but I have explored in depth how our species has managed to do just that. In 2011 I expanded the observations that ended the Violence chapter into one of the most optimistic books in recent memory, The Better Angels of Our Nature: Why Violence Has Declined—to the sputtering bewilderment of the standard critics of evolutionary psychology, who allege that that approach rules out hopes for social improvement and justifies a reactionary fatalism.1

But perhaps the main reason The Blank Slate could not be easily dismissed was that that it pointed out a taboo in modern intellectual life that so many readers recognized. I find it hard to credit that anyone with an acquaintance with biology, a pair of eyes, and a dose of common sense could really believe that men and women are indistinguishable, that children’s personalities are sculpted by their parents, that all individuals have the same native intelligence, that people can be trained to find anything as aesthetically pleasing as anything else, or that all aggression is a cultural fad. Yet these are the beliefs that respectable intellectuals are compelled to profess in public—while many of them, I can testify, profess very different beliefs in private. The Blank Slate, I like to think, gave voice to this intellectual discomfort.

The most frequently asked question posed to me about The Blank Slate is whether anything has changed in the intellectual climate in the dozen or so years since it was published. The answer is “Yes, a bit.” It used to be that any popular or academic writing that invoked biology to explain some aspect of human affairs was about the invoking of biology to explain human affairs, and had to acknowledge how terribly controversial the whole idea was. Today it’s possible to bring in biology where it promises insight and let the particular explanation stand or fall on its merits. In the past decade I have written popular articles on such topics as morality, genomics, bioethics, kinship, religion, and violence, and have brought in evolution or genetics where appropriate. No editor or reader has reacted in shock, as they surely would have in the 1980s and 1990s. And it’s not just me. Many of the sources in history and political science that I consulted for Better Angels invoked the biology of human nature where applicable, as do some of our major newspaper columnists.

At the same time, most of the popular press and other intellectual forums continue to be defiantly biophobic. Take just three examples:

 

Examples aside, can residual belief in the blank slate be documented systematically? In one instance it has been. In their article “Whither the Blank Slate?” the social scientists Mark Horowitz, William Yaworsky, and Kenneth Kickham published the results of their 2012 survey of a large sample of American sociologists.2 Comparing their results to those of a 1992 survey, they found that the proportion who identified evolutionary biology or sociology as among their theoretical perspectives had tripled in those two decades, from 2.5 percent to 8.3 percent. Moreover, 37 percent either “embrace evolutionary theory or are hopeful of its promise to shed new light on social phenomena,” also an increase from that sentiment two decades earlier.

But these findings also mean that two out of three sociologists do not believe that the theory which explains the origin of all living things can tell us anything about our own social life. Horowitz et al. sum up their results by saying, “Plainly, we see appreciable support for the blank-slate critique popularized by Pinker.” A majority of the theorists “deny the role of natural selection in shaping a range of human tendencies,” and their comments revealed many instances of dichotomous thinking such as this: “[B]ecause how we know the ‘world’ first and foremost through language, knowledges, and social meaning, the question of what is purely natural or what would nature look like stripped of the social is simply unanswerable. When we try, it leads to reductionism.”

Horowitz et al. supplemented their questionnaire with two surveys of textbooks on sociological theory (their own survey, and one by Richard Machalek and Michael Martin3), which found that few of the books even mentioned sociobiology or evolutionary psychology, and that in the ones that do, “the textbook authors characterize the field as mired in reductionism and genetic determinism. People appear as little more than ‘automatons’ propelled to act rigidly by their genes and impervious to cultural context. . . . [The] sociologists present an inexcusable ‘straw man’ given decades of advances in sociobiological theory and research.”

But could the hostility to genetics and evolution just be rooted in a defensible scholarly skepticism? In The Blank Slate I argued that much of the opposition is in fact political rather than scientific. And sure enough, the acceptance of biological explanations for the particular topics in the survey depended mostly on their political aromas. With one, the causes of homosexuality, a full seventy percent of sociologists agreed with the statement that “sexual orientation has biological roots.” Not coincidentally, this is the main issue on which the politically correct position goes against the blank slate: If gay people are born that way, so the dubious argument goes, they can’t be condemned for making an immoral choice, as religious and cultural conservatives claim. With only one other issue did a majority of sociologists find a biological explanation plausible: our taste for fats and sugars—which, according to current acceptable opinion, is exploited by agribusiness to addict us to junk food. With the politically neutral topic of a fear of snakes and spiders, about half of the respondents found an evolutionary component to the explanation plausible. From there the percentage went down as the political sensitivity went up, most obviously with issues concerning sex differences, where a majority rejected the obvious evolutionary explanation for why men, compared to women, are on average more promiscuous, violent, keen for pornography, and obsessed with virginity.

The sociologists themselves varied in their overall receptiveness to evolution, and once again Horowitz et al. identified the reason: “The overriding variable in each case is political ideology,” with “radicals being the most highly anti-biological,” and those embracing a “feminist theoretical perspective” (which is not the same as feminism itself) also being hostile. In large part this comes from a paranoia about the politics of evolutionary thinkers. Horowitz et al. quote a scholar who wrote that “few would deny the trend” in which “advocates of sociobiology have tended to be politically right-wing.” Actually, the advocates of sociobiology would deny it, because the trend does not exist. Two surveys of evolutionarily oriented graduate students in psychology and anthropology have shown that these students are politically no farther to the right than their nonevolutionary peers.4 This is, of course, consistent with my discussion in the Politics chapter of a flourishing Darwinian left.

These survey results confirm my conviction that the political, moral, and scientific arguments in The Blank Slate are as relevant today as when the book was published. But of course much has happened since the book went to press. Here are a few specific observations that help bring the various sections of the book up to date, together with updates on my own thinking and writing on these topics.

Preface. The first paragraph anticipated what I knew would be the main response among nervous scientists to the book’s theme: that genes and environment are so inextricably intertwined that we are never entitled to say anything clear about either of them. In my experience the inextricability response is an escape hatch that scientists try to wiggle through whenever they are asked questions about heritability whose answers make them uncomfortable. Of course genes and environments interact in complicated ways, but it’s the task of science to disentangle complex interactions into their components and relationships. In my essay “Why Nature and Nurture Won’t Go Away,” I call out this dodge, which I call “holistic interactionism,” and show that many questions about nature and nurture, when precisely stated, are in fact scientifically answerable.5

Chapter 1: The Official Theory. I attributed the expression blank slate to an extension of the medieval Latin term tabula rasa (scraped tablet), and to John Locke’s metaphor of “white paper.” The psychologist Melanie Asriel has informed me of an earlier and more precise attribution. In De Anima (“Of the Soul”), Aristotle writes that “mind is in a sense potentially whatever is thinkable, though actually it is nothing until it has thought . . . What it thinks must be in it just as characters may be said to be on a writing tablet on which as yet nothing actually stands written” (Book III, Part 4). Thirteen hundred years later, Thomas Aquinas alluded to Aristotle’s metaphor in Summa Theologica: “But the human intellect . . . is in potentiality with regard to things intelligible, and is at first ‘like a clean tablet on which nothing is written’” (Question 79, Article 2). Interestingly, both thinkers emphasized the infinite potential of human thought rather than just the emptiness of its initial state.

Chapter 3: The Last Wall to Fall. The scientific evidence against the blank slate and the ghost in the machine continue to pile up. The fields of cognitive, social, and affective neuroscience have been locating the physical substrates of ever-more-spiritual experiences, including empathy, moral reasoning, willed action, religious belief, and self-conscious reflection. Evolutionary psychology has matured into a major field of research (David Buss’s 2015 Handbook of Evolutionary Psychology, now in a second edition, presents the state of the art) and is taking advantage of novel quantitative techniques to detect the signatures of natural selection in the human genome. The genetic patterning of brain development, in its infancy when The Blank Slate was written, is now the focus of a big-science effort at the Allen Institute for Brain Science, while other national projects are planning to map the connectome (the wiring diagram of the human brain) and to simulate large-scale neural networks. These fields are growing so quickly and in so many directions that it’s sometimes hard to see how to unify the computational, neurobiological, and evolutionary levels of analysis. David Geary’s 2005 The Origin of Mind and John Anderson’s 2009 How Can the Human Mind Occur in the Physical Universe? are two ambitious attempts.

Ironically, in the same decade that the sciences of human nature have thoroughly exorcised the ghost in the machine, American bestseller lists have been filled with kitschy memoirs by medical charlatans and manipulated children claiming that their souls left their bodies during near-death experiences and glimpsed views of heaven. These frauds and delusions are exposed by the psychologist Julien Musolino in his 2015 book The Soul Fallacy.

Research in the last dozen years has also vindicated my discrediting of the noble savage. In chapter 2 of Better Angels I reviewed new evidence for high rates of lethal violence in nonstate societies. Though it drew the expected furious opposition from Rousseauan “anthropologists of peace,” subsequent reviews have borne out the conclusion.6 The heritability of aggressive tendencies (the trigger for the BBC screamfest) had a reasonable degree of support in 2002; it has an overwhelming degree today.7

Speaking of heritability, behavioral genetics, the most despised of the sciences of human nature, is enjoying a hearty last laugh. Though its findings (particularly its First Law, that all behavioral traits are heritable) are regularly denied by bien-pensant pundits and bestselling authors, it is just those findings that have escaped the replicability crisis which has recently embroiled mainstream psychology (in a recent replication extravaganza, around two thirds of highly publicized findings in psychology failed to replicate8). Unlike the cute and counterintuitive journalist bait that comes out of many social psychology labs, the findings of behavioral genetics are large in magnitude, are based on six- and seven-figure samples, have been replicated in many decades and countries, and have not been cherry-picked from among null results stashed in file drawers. In a paper called “The Top 10 Replicated Findings from Behavioral Genetics,”9 the authors barely conceal their delight in saying “We told you so.” One occasionally still sees pea-shooting about the methodology of behavioral genetics from critics who rediscover radical-science talking points from the 1970s, but the objections were met long ago and are easily flicked away.10

One of my assertions on the debunking of the noble savage, though, needs to be modified: that Derek Freeman had given the lie to Margaret Mead’s fieldwork on sexuality in Samoa. The anthropologist Paul Shankman has shown that in accusing Mead of being hoaxed by her teenage informants about their casual attitudes toward sex, Freeman was unfair to Mead, was at least as motivated by ideology as she was, and indeed appears to have been half-mad.11 So who’s right? An anthropologist colleague who has done field work in Samoa told me that they both were, but about different Samoans. Mead, a young woman at the time and hence a nobody in the Samoan status hierarchy, had access only to the hoi polloi, and indeed their sexual mores are freer than those prevailing in the West. Freeman, an alpha male, interviewed the aristocratic men, and their attitudes are more prudish and proprietary.

Chapter 4: Culture Vultures. Though some social scientists continue to insist on the Durkheimian dogma that culture belongs in a silo insulated from psychology and biology, the movement of intellectual life toward consilience is going forward without them, and there has been a blossoming of research on how individual choices propagate through social networks into large-scale cultural phenomena.

On the empirical side we are living in the era of Big Data: massive digital datasets on the cultural products of human behavior. I have used these datasets in several analyses of the quintessential cultural entity, language. In a chapter of my 2007 book The Stuff of Thought, I analyzed the acceptance of new words in the English language, using, among other things, an exhaustive dataset on baby names made available by the Social Security Administration.12 I was also part of a team led by Jean-Baptiste Michel and Erez Lieberman Aidan that developed the Google Ngram viewer (an online tool that plots the frequency of word strings over two centuries in five million books) and launched a new field we dubbed Culturomics.

On the theoretical side we have seen a flurry of applications of network science to phenomena such as social hubs, contagion, neighborhood effects, tipping points, virality, small worlds, and six degrees of separation. Duncan Watts’s Six Degrees and Nicholas Christakis and James Fowler’s Connected explain some of the striking new findings.13 For my part, I have written on the emergence of lingua francas and the global influence of speakers of different languages (with Shahar Ronen, César Hidalgo, and others),14 and on the spread of dangerous ideologies (based on the work of Michael Macy and his collaborators).15 The implications of social networks (traditional and digital) for health and psychological well-being are explained by the psychologist and journalist Susan Pinker (my sister) in her 2014 book The Village Effect.16

Another approach to the scientific understanding of culture is to analogize it directly to biological evolution, resulting in theories called “cultural evolution” or “cultural group selection.” In my essay “The False Allure of Group Selection” I argue that the analogy is usually misleading.17

Chapter 5: The Slate’s Last Stand. This chapter described three sets of findings that (I argued) were commonly misinterpreted as supporting a scientifically respectable version of the blank slate.

The first was the unexpectedly small number of protein-coding genes in the human genome. This is now universally recognized as a red herring: the rest of the genome is packed with information that regulates how the genes are expressed and thus can shape the character of the organism.

The second neo-blank-slate movement arose from the enthusiasm surrounding artificial neural network or connectionist models, which try to get away with minimal innate structure by capitalizing on the statistical information in large amounts of input. Much of this enthusiasm is now being carried over into the applied realm of artificial intelligence, where “deep learning” algorithms are powering the software behind face recognition, social network feeds, and other applications. The computer scientist Ernest Davis and the psychologist Gary Marcus have shown, though, that these algorithms are still woefully underpowered compared to common-sense human reasoning, which can handle not just the low-hanging fruit of statistically frequent concepts but an infinite range of brand-new ones, such as “moldy blueberry soda” and “gymnasts writing novels.” As a result, the statistical learning algorithms show the pattern of progress typical of artificial intelligence research: “Rapid progress . . . up to a mediocre level, followed by slower and slower improvement.”18 Within cognitive psychology itself, the unstructured connectionist pattern associators popular in the 1980s and 1990s have largely been superseded by Bayesian models, which also soak up statistical patterns in large datasets, but combine them with prior expectations of which hypotheses are most probable, a kind of innate knowledge.19

The third slate, neural plasticity, continues to be a major topic in neuroscience, but as the novelty of seeing changes in the brain that underlie learning has worn off and the realization that something has to change in the brain for learning to be possible has sunk in, hyperbolic claims that anyone can make their brain do anything have become less common. Research on plasticity now takes place alongside work on the genetic guidance of neural development20 and on the intricate structure of the human connectome.21

The yearning for some biological phenomenon that promises liberation from the seemingly fatalistic constraints of evolution and genetics is perennial, and it was inevitable that some new research topic would be seized upon as the longed-for release. That new topic is epigenetics, the regulation of gene expression. For as long as we’ve known that every cell in the body contains a complete copy of the genome, we’ve known that genes must be turned on and off in response to signals from outside the cell. Otherwise your eyeball would be pumping out liver enzymes all day while your liver cells spewed the proteins that make up your cornea. Recently some of the major mechanisms of gene regulation have come to be better understood, in particular, the attachment and removal of methyl molecules to particular places on the DNA strand, which affects whether the underlying gene is activated. Yet many people react to the uncovering of mechanisms of gene regulation as if it were a revolutionary discovery that calls for a rethinking of nature and nurture. Just as in the 1990s, when blank-slaters thought it was an amazing revelation that education, or psychotherapy, or learning a new language can actually change your brain! (as if learning might have taken place in the pancreas), today they are exclaiming that various kinds of experience can actually change the way your genes are expressed! (as if every cell in your body churned out every protein in the genome 24/7). Epigenetics has become the new silly putty, the shape-shifting, input-copying ingredient that gives us a license to circumvent careful analyses of heredity and environment and embrace a holistic interactionism. In addition to mistaking a biological necessity for a revolutionary discovery, the epigenetics craze confuses “the genes” in the sense of the information that organizes the brain during neural development with “the genes” in the sense of the entire protein-coding machinery of the body. Likewise it confuses “the environment” in the sense of information processed through the senses with “the environment” in the sense of the biochemical milieu of the DNA molecule.

Also inflating the epigenetics bubble is a set of findings that genuinely are surprising, namely that some epigenetic markers attached to the DNA strand as a result of environmental signals (generally stressors such as starvation or maternal neglect) can be passed from mother to offspring. These intergenerational effects on gene expression are sometimes misunderstood as Lamarckian, but they’re not, because they don’t change the DNA sequence, are reversed after one or two generations, are themselves under the control of the genes, and probably represent a Darwinian adaptation by which organisms prepare their offspring for stressful conditions that persist on the order of a generation. (It’s also possible that they are merely a form of temporary damage.) Moreover, most of the transgenerational epigenetic effects have been demonstrated in rodents, who reproduce every few months; the extrapolations to long-lived humans are in most instances conjectural or based on unreliably small samples. Many biologists are starting to express their exasperation with the use of epigenetics as “the currently fashionable response to any question to which you do not know the answer,” as the epidemiologist George Davey Smith has put it.22

Part II: Fear and Loathing. Though evolutionary psychologists and behavioral geneticists no longer walk around with a target painted on their backs (and as I mentioned, I suffered no dirty tricks in the wake of The Blank Slate), the intimidation and censoring of heterodox thinkers in American universities may have worsened since 2002. This baleful development is analyzed by the civil liberties lawyer Greg Lukianoff in his recent books Freedom from Speech (2014) and Unlearning Liberty (2012); Lukianoff is also the director of the Foundation for Individual Rights in Education (www.thefire.org), which tries to combat restrictions on speech in American universities. My own analysis of the ethics of studying “dangerous ideas” may be found in my foreword to John Brockman’s 2006 collection What Is Your Dangerous Idea?23

Chapter 6: Political Scientists described the blood libel against the anthropologist Napoleon Chagnon, a live issue when the book was written. In response to overwhelming documentation that exonerated Chagnon and exposed his accuser as a mountebank, the American Anthropological Association rescinded the 2000 report by its kangaroo court. Chagnon has told his side of the story in a 2013 autobiography titled (of course) Noble Savages. The saga is masterfully recounted by the medical historian Alice Dreger in “Darkness’s Descent on the American Anthropological Association”24 and her 2015 book Galileo’s Middle Finger. In that book, Dreger reports another scandal that would fit right into this chapter: the case of the sexuality researcher Michael Bailey, whose life was made a living hell by transgender activists who took umbrage at a theory he endorsed in his 2003 book The Man Who Would Be Queen.25

Part III: Human Nature with a Human Face. Like Molière’s Bourgeois gentleman who was delighted to learn that he had been speaking prose all his life, after The Blank Slate was published I was delighted to discover that I was a “humanist,” and have since become a spokesperson for the movement that advocates a secular morality based on reason, science, and human flourishing. Recent manifestoes for humanism include Greg Epstein’s Good Without God (2009), Roy Speckhardt’s Creating Change Through Humanism (2015), Philip Kitcher’s Life After Faith (2014), and A. C. Grayling’s The God Argument (2013).

The theme of the last chapter in this section, “The Fear of Nihilism,” namely that we can enjoy a robust conception of meaning and morality without the religious conception of the soul, has been thrust into public awareness by the quartet of “new atheist” bestsellers that appeared between 2005 and 2007: Sam Harris’s The End of Faith, Richard Dawkins’s The God Delusion, Daniel Dennett’s Breaking the Spell, and Christopher Hitchens’s God Is Not Great. For an exploration of the roots of secular morality, I recommend my wife Rebecca Newberger Goldstein’s Betraying Spinoza: The Renegade Jew Who Gave Us Modernity (2006) and her Plato at the Googleplex: Why Philosophy Won’t Go Away (2014). The passions aroused by secular and religious conceptions of meaning are brought to life in her 2010 novel Thirty-Six Arguments for the Existence of God: A Work of Fiction.

Part IV: Know Thyself. A deeper exploration of the foibles of cognition, emotion, and social relations may be found in my 2007 book The Stuff of Thought and in the two psychological chapters (8 and 9) in The Better Angels of Our Nature. Many other accessible books have recently expanded on the content of these chapters, including Paul Bloom’s How Pleasure Works (2010) and Just Babies (2013), Jonathan Haidt’s The Righteous Mind (2012), Joshua Greene’s Moral Tribes (2013), Bruce Hood’s SuperSense (2009), Robert Trivers’s The Folly of Fools (2011), Robert Kurzban’s Why Everyone (Else) Is a Hypocrite (2011), and Daniel Kahneman’s Thinking Fast and Slow (2011).

Chapter 16: Politics. Thomas Sowell’s theory of the contrasting theories of human nature that underlie right-wing and left-wing political ideologies has been joined by several other attempts to distill out the essence of each one. In Moral Politics (1996), the linguist George Lakoff argues that each ideology understands society through a different metaphor of a family, the right seeing it as run by a strict father, the left by a nurturing parent.26 Jonathan Haidt, in The Righteous Mind, suggests that conservatives moralize an expansive set of ideals, which include deference to authority, conformity to social norms, and the protection of purity and sacredness, whereas liberals moralize only fairness, the care of those in need, and the prevention of harm (see also my 2008 essay “The Moral Instinct”27). And in Better Angels (chapter 3), I add that the geographic distribution of political ideologies in the United States, with conservative “red states” in the South and Southwest, and liberal “blue states” in the north and along the coasts, is a legacy of how those regions were settled.28 The South and Southwest remained a lawless frontier for much of American history, and its men developed a culture of honor (see chapter 17), while looking to women, the church, and norms of temperance to tame its violent excesses. The northern and coastal states inherited European institutions of government and the associated culture of dignity, which had grown out of a centuries-long “civilizing process.”

The four theories are related. If children are Hobbesian brutes, they need a strict father; if they are noble savages, they will flourish under the care of a nurturant parent. If people are inherently flawed, their behavior must be restrained by custom, authority and sacred values, whereas if they are capable of wisdom and reason, they can determine for themselves what is fair, harmful, or hurtful. And the American geographic divide arose not so much from different conceptions of human nature as from different strategies of how best to tame it.

Chapter 17: Violence. My 2011 book The Better Angels of Our Nature grew out of the observations in this chapter that violence has declined over the course of human history (pages 330–331 and 333–336; see also chapter 9, pages 166–169). The new book expands the analysis of violence developed in this chapter, but does not supersede it, because the focus in this one is on the widespread denial that violence has any evolutionary or genetic component at all.

Chapter 18: Gender. My comment that The Blank Slate did not bring out intemperate reactions is not exactly true. It did not lead to any intemperate reactions directed at me. But it did lead to a firestorm directed at Lawrence Summers.

Early in 2005 Summers, then President of Harvard University, was invited to deliver some impromptu remarks at a closed conference on gender imbalances in science, technology, engineering, and mathematics (STEM). Summers repeated the labor economists’ commonplace that a disparity among categories of people in professional outcomes cannot by itself be taken as proof of discrimination, because such disparities could also be the result of differences in training, talent, life priorities, and other average traits. Summers had read The Blank Slate, and with the literature review from the Gender chapter in mind, he noted that four hypotheses had to be considered to explain gender disparities in STEM: the persistence of gender discrimination and other barriers; differences between the sexes in their de facto responsibilities for child-rearing; differences between the sexes in their average talents, temperaments, and interests; and differences between the sexes in the variability of their talents, temperaments, and interests, with more males at the extremes. Infamously, during the course of this explication he uttered the phrase “intrinsic aptitude.” In the audience was the biologist Nancy Hopkins (a former neighbor, MIT colleague, and good friend of mine), who, just as infamously, said that upon hearing his speech didn’t know whether she would “throw up or black out.” After she reported the contents to a Boston Globe writer, the resulting story set off a cascade of denunciations and protests that culminated in Summers’s resignation in 2006 (though other events figured in the resignation as well.)

Those who read the transcript of Summers’s remarks came away impressed by their caution and nuance, but that proved irrelevant. The response from Summers’s critics could have jumped off the pages of the “Fear and Loathing” section: straw-manning, statistical illiteracy, a refusal to look at data, a confusion of fairness with sameness, and a vindication of what has come to be called Godwin’s Law (“As an online discussion grows longer, the probability of a comparison involving Nazis or Hitler approaches one”).29 To the credit of Harvard, several colleagues were appalled by this race to the bottom and called for a civil and evidence-based airing of the issues. In April, 2005, Harvard’s Mind/Brain/Behavior Initiative sponsored a conversation on innate sex differences between me and the developmental psychologist Elizabeth Spelke, a good friend and longtime colleague. I like to think that everyone who attended the packed event, watched the video, or read the edited transcript came away thinking that even the most fraught issues on human nature can be debated in a constructive manner.30

This came too late for Summers, who continues to be defamed as the guy who thinks that “women can’t do math.” But in my view, his remarks on sex differences in interests and life priorities have been largely vindicated by subsequent literature reviews, such as the new edition of David Geary’s Male, Female (2009) and Susan Pinker’s The Sexual Paradox (2008). Even his more incendiary remarks on mathematical ability and on gender discrimination have been shown to have important grains of truth.

Though Summers is remembered as having invoked sex differences in average abilities, what he really emphasized was sex differences in the variance in abilities, since the imbalance of men at the high end of the distribution was the phenomenon relevant to the (rather exotic) issue in question, namely the underrepresentation of women in elite university science and engineering departments. In 2006 the psychologists Steve Strand, Ian Deary, and Pauline Smith analyzed the test scores of an unprecedented sample of 300,000 British pupils.31 They found that while the girls had a slightly higher average score in verbal reasoning and the boys had a slightly higher average score in quantitative reasoning, the boys were substantially overrepresented at the high and low ends of the range of quantitative scores (making up 60 percent of the pupils in the highest tenth).

Another partial vindication has come from a set of studies conducted by the psychologists Wendy Williams and Stephen Ceci.32 The iffiest claim in Summers’s remarks had been his conjecture that discrimination was the least important of the four causes of gender disparities in STEM. It was iffy because at the time there was little basis for ranking them one way or another. Williams and Ceci analyzed a number of datasets on gender discrimination in interviewing and hiring professors and in grant and manuscript reviewing. Not only did they find little evidence for discrimination, but in new studies that used the gold standard for testing for prejudice—gatekeepers’ responses to fake résumés—they reported that “men and women faculty members from all four fields [biology, engineering, economics, and psychology] preferred female applicants 2:1 over identically qualified males”—a prejudice opposite in direction to the one that could explain female under-representation in STEM fields.

The second half of the Gender chapter discussed the psychology and politics of rape. As I mentioned, the dogmatic and illiberal atmosphere that surrounded the topic at the time is even worse today. No man can get away with discussing the problem in the mainstream press, but trenchant exposés have been penned by the writers Emily Yoffe, Heather MacDonald, and Judith Shulevitz and by the judge Nancy Gertner.33

In the course of writing Better Angels I came across two ironies in the popular understanding of rape. While researching a section called “Women’s Rights and the Decline of Rape and Battering,” I reread Susan Brownmiller’s 1975 classic Against Our Will, which is widely credited with the idea that rape has nothing to do with sex but instead is a political tactic for male dominance. To my surprise, that claim barely figured in the book. Brownmiller mentioned it briefly in two places, noting that she had adapted it from the theories of an old communist professor of hers. The rest of the book documented the history of rape and the all-too-frequent trivialization of it in the legal system and popular culture of the day, and I found it thoroughly engaging and persuasive.

I also analyzed Bureau of Justice statistics and discovered that between 1973 and 2008 the rate of sexual assault in the United States plummeted by 80 percent. (Indeed, by 2015 it had fallen another 22 percent).34 As far as I know I am the only writer who has called attention to this remarkable development, while most rape activists assume that things are as bad as ever or getting worse. So contrary to the claim that evolutionary psychology fatalistically implies that rape is inevitable, while the rape-is-not-sex dogma is necessary to effect social change, it’s the evolutionary psychologist who celebrates our ability to reduce the rate of rape, while the blank-slaters imply that four decades of concern with the crime have been futile.

Chapter 19: Children. This is my favorite chapter, and indeed one of my favorite things I have ever written. It was also (putting aside the Summers brouhaha) the most controversial. Virtually all the objections came from two misunderstandings that I had grimly anticipated, despite my having mustered every microgram of expository skill to forestall them. In my experience no one understands what the Second and Third Laws of Behavioral Genetics are about, no matter how patiently they are explained. Everyone confuses them with the First Law and concludes that the only lesson of behavioral genetics is that “it’s all in the genes.” The other stubborn misunderstanding is that if parents can’t mold their children’s personalities and intellects, then parenting “doesn’t matter.”

How well have the Three Laws stood the test of time? Very. Each is among Plomin et al.’s “Top 10 Replicated Findings in Behavioral Genetics.”35 They have also been confirmed in a massive new meta-analysis of twin studies embracing thousands of publications and millions of twin pairs.36 The heritability of intelligence (the prime manifestation of the First Law) has recently been demonstrated by an entirely new method which complements the classic studies of twins and adoptees. Genome-wide association studies, which aggregate tiny statistical effects of hundreds of thousands of genes in samples of thousands of unrelated people, have shown that about half the variation in intelligence can be predicted from looking at the genes, a figure that is similar to the one estimated by the traditional methods.37

This brings me to what my former student James Lee, together with Christopher Chabris and our other collaborators, calls the Fourth Law of Behavioral Genetics: “A typical human behavioral trait is associated with very many genetic variants, each of which accounts for a very small percentage of the behavioral variability.”38 It was a good thing that in the Children chapter I resisted the temptation to trumpet recent discoveries of single genes that were claimed to explain appreciable differences in psychological traits across the human population: few, if any, such genes exist. This became personally clear to me when I was one of the first people to have his genome sequenced and discovered that I carried a gene for baldness (a condition from which, to put it mildly, I do not suffer).39 Like many of the “gene for X” claims of the 1990s and 2000s, it was a false positive that resulted from snooping around the genome for an association between a genetic variant and a trait in a paltry sample of people. Studies that test massive numbers of people can find genes with reliable but small effects: Lee, Chabris, and I are part of a consortium that recently identified three genetic loci that each accounts for about a third of an IQ point,40 and subsequent studies by the team have identified scores more and linked them to mechanisms of brain development. (Plus ça change: As I wrote these words, an email arrived from Lee, who was about to present the newest findings at a genetics conference, telling me that the president of the society had just given a keynote address that preemptively denounced the work as racist, sexist, and homophobic.)

Also among the Top Ten replicable results is the hard-for-many-to-swallow finding that measures of the environment, such as parenting practices and socioeconomic status, are heritable (as are correlations between these measures and the traits of children). At first this sounds paradoxical: how could our genes affect our environments? They can and do via our genetically influenced life choices, which put us in particular environments, and via other people’s reactions to our genetically influenced traits. In other words, children’s intelligence and personality affect the way their parents treat them and which social milieu they end up in, not just (or even) the other way around.41

There also has been progress in solving the puzzle raised by the Third Law: What is the large but mysterious Mr. Jones factor that shapes people’s intelligence, personality, and life outcomes, but that cannot be identified with their genes, their families, or their culture? (A simple version of this puzzle is: how can we explain the differences between identical twins reared together?) In the chapter I suggested that the term “unique environment” (the hypothetical experiences that befall one child in a family but not another) is a misnomer, and that the variation may result from random accidents in the development of the brain. Geneticists sometimes call this “the dismal prospect,” since it puts a low ceiling on how well we can ever predict people’s personality and intellect.

I personally don’t find it dismal, but it doesn’t matter what I or anyone else thinks, because it increasingly appears to be the reality. Epidemiologists, frustrated by their inability to explain the pack-a-day nonagenarian and the young athlete who keels over from a heart attack (even after taking their genes into account) are starting to acknowledge the enormous influence of Lady Luck in the working of our bodies.42 That must apply in even greater measure to the working of our brains. Back in 2002 it was already known that the genes can’t wire the brain down to the last synapse, so there is tremendous room for random zigs and zags in brain development. Since then neuroscientists have shown that the prospect may be even more dismal than that, because there is also tremendous room for random variation to creep into our genomes themselves. Each of us inherits about sixty new mutations,43 and they appear to be major contributors to psychiatric disorders such as schizophrenia and autism.44 Since the genes that cause susceptibility to psychological disorders appear to be the same as the genes that underlie ordinary variation among healthy people (another of the Top Ten replicated findings from behavioral genetics45), these mutations almost certainly contribute to our personalities. And from there it gets even more dismal, because as our brains grow and function, our neurons fill up with still more mutations, large and small, which could readily affect how our brains work.46 If these germ-line and somatic mutations are a significant part of the Mr. Jones factor, our genes may have an even bigger role in shaping us than classical behavioral genetics has estimated, because these mutations are not shared among biological siblings or identical twins, whose similarities have heretofore been the main source of evidence about genetic influence.

The other possible explanation for the Third Law (not mutually exclusive with mutations and other developmental noise) is that the mysterious shapers include capricious but formative experiences that make up our unique life lines. Plomin et al. suggest that environmental influences, like genetic influences, might be distributed across thousands of events, each with a tiny effect.47 Judith Rich Harris, whose 1998 book The Nurture Assumption was a major inspiration for this chapter, wrote a follow-up in 2006 called No Two Alike, which developed her hypothesis that children undergo unique experiences that assign them social roles within a peer group, and which they build upon in developing their personalities. The Nurture Assumption was published in a new edition in 2008, and both of Harris’s brilliant and witty books are required reading for anyone with an interest in what makes us what we are.

Chapter 20: The Arts. Like the Children chapter, this one defied my expectations on which issues get people riled up, because it attracted more controversy than the discussions of race, gender, violence, politics, or inequality. Several critics thought I was attacking the artistic merits of modernism, which I had neither the qualifications nor the intention of doing. (I have nothing against Virginia Woolf, Pablo Picasso, or the Bauhaus, and indeed my own tastes in art run toward modernism.) Far from pretending to be an art critic, I was trying to connect the direction that modern and then postmodern styles took in the twentieth century to the book’s main theme, the denial of human nature—in this case the corollary of the Blank Slate that aesthetic pleasure is a social construction with no relation to our perceptual and emotional faculties. And this corollary, I suggested, can in turn help explain the declining vigor and prestige of certain forms of elite art, criticism, and scholarship.

If I were to write the chapter today, I would have drawn finer distinctions. The great works of modernism in fiction, art, and architecture did engage our aesthetic faculties, of course, just in nontraditional ways. And the rejection of beauty was stronger in some art forms (such as modern elite music) than in others (such as fiction and poetry). It was when modernism exerted a chokehold over elite arts, and then spawned postmodernism, that the denial of intrinsic beauty went overboard and gave us genres such as atonal music, brutalist architecture, postmodernist lit-crit, and grotesque conceptual art.

The other theme of the chapter is that the much-bemoaned decline of the humanities is in part self-inflicted, the result of a contempt for scientific ways of thinking and a rejection of new ideas that the sciences of human nature could inject into artistic analysis. For evidence that little has changed, see my 2013 exchange with the critic and editor Leon Wieseltier.48

I have also been disappointed by the slow pace of the effort to use psychology and biology to provide insight into artistic works. (Some exceptions include Denis Dutton’s The Art Instinct (2008), Aniruddh Patel’s Music, Language, and the Brain (2007), and Jonathan Gottschall’s The Storytelling Animal (2012).) One impediment has been a lack of collaboration between scientists and humanities scholars who could complement each other’s expertise. The humanities scholars are correct that scientists’ forays into explaining art have been, by their standards, shallow and simplistic. All the more reason for them to reach out and combine their erudition about individual works and genres with scientific insight into human emotions and aesthetic responses. Better still, universities should train a new generation of scholars who are fluent in both of the two cultures. But graduate students in the humanities tell me that any discussion that mentions Darwin or game theory rather than Derrida and Foucault will reliably vindicate Godwin’s Law.

Another impediment to consilience is a blind spot among the science-friendly scholars who have tried to bridge the two cultures. As I point out in my review of Gottschall and David Sloan Wilson’s The Literary Animal (a 2007 collection of essays on Darwinian literary criticism), these scholars tend to draw on a tiny fraction of the ideas that could provide insight into the arts, mainly, the evolutionary psychology of mating.49 And too often they invoke a biologically dubious folk-conception of evolution in which all adaptations are for “group cohesion.” A more powerful application of science to art would invoke the combinatorial richness of cognitive science and the evolutionary analysis of social conflicts, such as those explored in the Many Roots of Our Suffering chapter.

A Final Reflection. Though I’ve emphasized the ways in which The Blank Slate is as relevant today as it was in 2002, it would be a closed mind indeed that did not change at all in more than a dozen years. My biggest turnaround has been a shift in emphasis between the darker and brighter sides of human nature. I continue to believe that the human prospect is more tragic than utopian, that out of the crooked timber of humanity no truly straight thing can be made, and that we are not stardust, we are not golden, and there is no way we are getting ourselves back to the garden. At the same time, my world view has lightened up since The Blank Slate was published. My acquaintance with the statistics of human progress, starting with violence but now embracing longevity, health, literacy, and material well-being, have fortified my belief in the second half of the ending of chapter 17: that with many of our ills, human nature is the problem, but human nature is also the solution.