The sciences of human nature can strengthen the interests of women by
separating
those herrings from the truly important goals.
Steven-Pinker-The-Blank-Slate 1
And if a man rapes for sex, that does not mean that he "just can't help it" or that we have to excuse him, any more than we have to excuse the man who shoots the owner of a liquor store to raid the cash register or who bashes a driver over the head to steal his BMW.
The great contribution of feminism to the morality of rape is to put issues of consent and coercion at center stage.
The ultimate motives of the rapist are irrelevant.
Finally, think about the humanity of the picture that the gender-feminist theory has painted. As the equity feminist Wendy McElroy points out, the theory holds that "even the most loving and gentle husband, father, and son is a beneficiary of the rape of women they love. No ideology that makes such vicious accusations against men as a class can heal any wounds. It can only provoke hostility in return. "86 {364}
~
Does one need scientific methodology in order to conclude that the anti-female propaganda that permeates our nation's cultural output promotes a climate in which acts of sexual hostility directed against women are not only tolerated but ideologically encouraged?
? ? ? ? Brownmiller asked a revealing rhetorical question:
McElroy responded: "The answer is a clear and simple 'yes. ' One needs scientific methodology to verify any
empirical claim. " And she called attention to the consequences of Brownmiller's attitude: "One of the casualties of the new dogma on rape has been research. It is no longer 'sexually correct' to conduct studies on the causes of rape, because -- as any right-thinking person knows -- there is only one cause: patriarchy. Decades ago, during the heyday of liberal feminism and sexual curiosity, the approach to research was more sophisticated. "87 McElroy's suspicions are borne out by a survey of published "studies" of rape that found that fewer than one in ten tested hypotheses or used scientific methods. 88
Scientific research on rape and its connections to human nature was thrown into the spotlight in 2000 with the publication of A Natural History of Rape. Thornhill and Palmer began with a basic observation: a rape can result in a conception, which could propagate the genes of the rapist, including any genes that had made him likely to rape. Therefore, a male psychology that included a capacity to rape would not have been selected against, and could have been selected for. Thornhill and Palmer argued that rape is unlikely to be a typical mating strategy because of the risk of injury at the hands of the victim and her relatives and the risk of ostracism from the community. But it could be an opportunistic tactic, becoming more likely when the man is unable to win the consent of women, alienated from a community (and thus undeterred by ostracism), and safe from detection and punishment (such as in wartime or pogroms). Thornhill and Palmer then outlined two theories. Opportunistic rape could be a Darwinian adaptation that was specifically selected for, as in certain insects that have an appendage with no function other than restraining a female during forced copulation. Or rape could be a by-product of two other features of the male mind: a desire for sex and a capacity to engage in opportunistic violence in pursuit of a goal. The two authors disagreed on which hypothesis was better supported by the data, and they left that issue unresolved.
No honest reader could conclude that the authors think rape is "natural" in the vernacular sense of being welcome or unavoidable. The first words of the book are, "As scientists who would like to see rape eradicated from human
life . . . ," which are certainly not the words of people who think it is inevitable. Thornhill and Palmer discuss the environmental circumstances that {365} affect the likelihood of rape, and they offer suggestions on how to reduce it. The idea that most men have the capacity to rape works, if anything, in the interests of women, because it calls for vigilance against acquaintance rape, marital rape, and rape during societal breakdowns. Indeed, the analysis jibes with Brownmiller's own data that ordinary men, including "nice" American boys in Vietnam, may rape in wartime. For that matter, Thornhill and Palmer's hypothesis that rape is on a continuum with the rest of male sexuality makes them strange allies with the most radical gender feminists, such as Catharine MacKinnon and Andrea Dworkin, who said that "seduction is often difficult to distinguish from rape. In seduction, the rapist often bothers to buy a bottle of wine. "89
Most important, the book focuses in equal part on the pain of the victims. (Its draft title was Why Men Rape, Why Women Suffer. ) Thornhill and Palmer explain in Darwinian terms why females throughout the animal kingdom resist being forced into sex, and argue that the agony that rape victims feel is deeply rooted in women's nature. Rape subverts female choice, the core of the ubiquitous mechanism of sexual selection. By choosing the male and the circumstances for sex, a female can maximize the chances that her offspring will be fathered by a male with good genes, a willingness and ability to share the responsibility of rearing the offspring, or both. As John Tooby and Leda Cosmides have put it, this ultimate (evolutionary) calculus explains why women evolved "to exert control over their own sexuality, over the terms of their relationships, and over the choice of which men are to be the fathers of their children. " They resist being raped, and they suffer when their resistance fails, because "control over their sexual choices and relationships was wrested from them. "90
Thornhill and Palmer's theory reinforces many points of an equity-feminist analysis. It predicts that from the woman's point of view, rape and consensual sex are completely different. It affirms that women's repugnance toward rape is not a symptom of neurotic repression, nor is it a social construct that could easily be the reverse in a different culture. It predicts that the suffering caused by rape is deeper than the suffering caused by other physical traumas or body violations. That justifies our working harder to prevent rape, and punishing the perpetrators more severely, than we do for other kinds of assault. Compare this analysis with the dubious claim by two gender feminists that an aversion to rape has to be pounded into women by every social influence they can think of:
Female fear. . . [results] not only from women's personal backgrounds but from what women as a group have imbibed from history, religion, culture, social institutions, and everyday social interactions. Learned early in life, female fear is continually reinforced by such {366} social institutions as the school, the church, the law, and the press. Much is also learned from parents, siblings, teachers, and friends. 91
But despite the congeniality of their analysis to women's interests, Thornhill and Palmer had broken a taboo, and the response was familiar: there were demonstrations, disruptions of lectures, and invective that would curdle your hair, as the popular malaprop has it. "Latest nauseating scientific theory" was a typical reaction, and radical scientists
? ? ? ? ? ? ? applied their usual standards of accuracy to denounce it. Hilary Rose, discussing a presentation of the theory by another biologist, wrote, "The sociobiologist David Barash's appeal in defense of his misogynist claims that men are naturally predisposed to rape, 'If Nature is sexist don't blame her sons,' can no longer plug into the old deference to science as the view from nowhere. "92 Barash, of course, had said no such thing; he had referred to rapists as criminals who should be punished. The science writer Margaret Wertheim began her review of Thornhill and Palmer's book by calling attention to a recent epidemic of rape in South Africa. 93 Pitting the theory that rape is "a byproduct of social conditioning and chaos" against the theory that rape has evolutionary and genetic origins, she sarcastically wrote that if the latter were true, "South Africa must be a hothouse for such genes. " Two slurs for the price of one: the statement puts Thornhill and Palmer on the simplistic side of a false dichotomy (in fact, they devote many pages to the social conditions fostering rape) and slips in the innuendo that their theory is racist, too. The psychologist Geoffrey Miller, in his own mixed review of the book, diagnosed the popular reaction:
The Natural History of Rape has already suffered the worst possible fate for a popular science book. Like The Descent of Man and The Bell Curve, it has become an ideological touchstone. People who wish to demonstrate their sympathy for rape victims and women in general have already learned that they must dismiss this book as sexist, reactionary pseudo-science. News stories that treat the book as a symptom of chauvinist cultural decay have greatly outnumbered reviews that assess it as science. Viewed sociologically, turning books into ideological touchstones can be useful. People can efficiently sort themselves out into like-minded cliques without bothering to read or think. However, there can be more to human discourse than ideological self-advertisement. 94
It's unfortunate that Thornhill and Palmer themselves set up a dichotomy between the theory that rape is an adaptation (a specifically selected sexual strategy) and the theory that it is a by-product (a consequence of using violence in general), because it diverted attention from the more basic claim that rape has something to do with sex. I think their dichotomy is drawn too {367} sharply. Male sexuality may have evolved in a world in which women were more discriminating than men about partners and occasions for sex. That would have led men to treat female reluctance as an obstacle to be overcome. (Another way to put it is that one can imagine a species in which the male could become sexually interested only if he detected reciprocal signs of interest on the part of the female, but that humans do not appear to be such a species. ) How the woman's reluctance is overcome depends on the rest of the man's psychology and on his assessment of the circumstances. His usual tactics may include being kind, persuading the woman of his good intentions, and offering the proverbial bottle of wine, but may become increasingly coercive as certain risk factors are multiplied in: the man is a psychopath (hence insensitive to the suffering of others), an outcast (hence immune to ostracism), a loser (with no other means to get sex), or a soldier or ethnic rioter who considers an enemy subhuman and thinks he can get away with it. Certainly most men in ordinary circumstances do not harbor a desire to rape. According to surveys, violent rape is unusual in pornography and sexual fantasies, and according to laboratory studies of men's sexual arousal, depictions of actual violence toward a woman or signs of her pain and humiliation are a turnoff. 95
What about the more basic question of whether the motives of rapists include sex? The gender-feminist argument that they do not points to the rapists who target older, infertile women, those who suffer from sexual dysfunction during the rape, those who coerce nonreproductive sexual acts, and those who use a condom. The argument is unconvincing for two reasons. First, these examples make up a minority of rapes, so the argument could be turned around to show that most rapes do have a sexual motive. And all these phenomena occur with consensual sex, too, so the argument leads to the absurdity that sex itself has nothing to do with sex. And date rape is a particularly problematic case for the not-sex theory. Most people agree that women have the right to say no at any point during sexual activity, and that if the man persists he is a rapist -- but should we also believe that his motive has instantaneously changed from wanting sex to oppressing women?
On the other side there is an impressive body of evidence (reviewed more thoroughly by the legal scholar Owen Jones than by Thornhill and Palmer) that the motives for rape overlap with the motives for sex:96
? Coerced copulation is widespread among species in the animal kingdom, suggesting that it is not selected against and may sometimes be selected for. It is found in many species of insects, birds, and mammals, including our relatives the orangutans, gorillas, and chimpanzees.
? Rape is found in all human societies.
? Rapists generally apply as much force as is needed to coerce the victim into sex. They rarely inflict a serious or fatal injury, which would preclude {368} conception and birth. Only 4 percent of rape victims sustain serious injuries, and fewer than one in five hundred is murdered.
? Victims of rape are mostly in the peak reproductive years for women, between thirteen and thirty-
? ? ? ? ? ? ? five, with a mean in most data sets of twenty-four. Though many rape victims are classified as children (under the age of sixteen), most of these are adolescents, with a median age of fourteen. The age distribution is very different from that of victims of other violent crimes, and is the opposite of what would happen if rape victims were picked for their physical vulnerability or by their likelihood of holding positions of power.
? Victims of rape are more traumatized when the rape can result in a conception. It is most psychologically painful for women in their fertile years, and for victims of forced intercourse as opposed to other forms of rape.
? Rapists are not demographically representative of the male gender. They are overwhelmingly young men, the age of the most intense sexual competitiveness. The young males who allegedly have been "socialized" to rape mysteriously lose that socialization as they get older.
? Though most rapes do not result in conception, many do. About 5 percent of rape victims of reproductive age become pregnant, resulting in more than 32,000 rape-related pregnancies in the United States each year. (That is why abortion in the case of rape is a significant issue. ) The proportion would have been even higher in prehistory, when women did not use long-term contraception. 97 Brownmiller wrote that biological theories of rape are "fanciful" because "in terms of reproductive strategy, the hit or miss ejaculations of a single-strike rapist are a form of Russian roulette compared to ongoing consensual mating. "98 But ongoing consensual mating is not an option for every male, and dispositions that resulted in hit-or-miss sex could be evolutionarily more successful than dispositions that resulted in no sex at all. Natural selection can operate effectively with small reproductive advantages, as little as 1 percent.
~
The payoff for a reality-based understanding of rape is the hope of reducing or eliminating it. Given the theories on the table, the possible sites for levers of influence include violence, sexist attitudes, and sexual desire.
Everyone agrees that rape is a crime of violence. Probably the biggest amplifier of rape is lawlessness. The rape and abduction of women is often a goal of raiding in non-state societies, and rape is common in wars between states and riots between ethnic groups. In peacetime, the rates of rape tend to track rates of other violent crime. In the United States, for example, the rate of forcible rape went up in the 1960s and down in the 1990s, together with the rates of other violent crimes. 99 Gender feminists blame violence against women on civilization and social institutions, but this is exactly backwards. {369} Violence against women flourishes in societies that are outside the reach of civilization, and erupts whenever civilization breaks down.
Though I know of no quantitative studies, the targeting of sexist attitudes does not seem to be a particularly promising avenue for reducing rape, though of course it is desirable for other reasons. Countries with far more rigid gender roles than the United States, such as Japan, have far lower rates of rape, and within the United States the sexist 1950s were far safer for women than the more liberated 1970s and 1980s. If anything, the correlation might go in the opposite direction. As women gain greater freedom of movement because they are independent of men, they will more often find themselves in dangerous situations.
What about measures that focus on the sexual components of rape? Thornhill and Palmer suggested that teenage boys be forced to take a rape-prevention course as a condition for obtaining a driver's license, and that women should be reminded that dressing in a sexually attractive way may increase their risk of being raped. These untested prescriptions are an excellent illustration of why scientists should stay out of the policy business, but they don't deserve the outrage that followed. Mary Koss, described as an authority on rape, said, "The thinking is absolutely unacceptable in a democratic society. " (Note the psychology of taboo -- not only is their suggestion wrong, but merely thinking it is "absolutely unacceptable. ") Koss continues, "Because rape is a gendered crime, such recommendations harm equality. They infringe more on women's liberties than men's. "100
One can understand the repugnance at any suggestion that an attractively dressed woman excites an irresistible impulse to rape, or that culpability in any crime should be shifted from the perpetrator to the victim. But Thornhill and Palmer said neither of those things. They were offering a recommendation based on prudence, not an assignment of blame based on justice. Of course women have a right to dress in any way they please, but the issue is not what women have the right to do in a perfect world but how they can maximize their safety in this world. The suggestion that women in dangerous situations be mindful of reactions they may be eliciting or signals they may inadvertently be sending is just common sense, and it's hard to believe any grownup would think otherwise -- unless she has been indoctrinated by the standard rape-prevention programs that tell women that "sexual assault is not an act of sexual gratification" and that "appearance and attractiveness are not relevant. "101 Equity feminists have called attention to
? ? ? ? ? ? the irresponsibility of such advice, in terms far harsher than anything by Thornhill and Palmer. Paglia, for example, wrote:
For a decade, feminists have drilled their disciples to say, "Rape is a crime of violence but not sex. " This sugar-coated Shirley Temple {370} nonsense has exposed young women to disaster. Misled by feminism, they do not expect rape from the nice boys from good homes who sit next to them in class. . . . These girls say, "Well, I should be able to get drunk at a fraternity party and go upstairs to a guy's room without anything happening. " And I say, "Oh, really? And when you drive your car to New York City, do you leave your keys on the hood? " My point is that if your car is stolen after you do something like that, yes, the police should pursue the thief and he should be punished. But at the same time, the police -- and I -- have the right to say to you, "You stupid idiot, what the hell were you thinking? "102
Similarly, McElroy points out the illogic of arguments like Koss's that women should not be given practical advice that "infringes more on women's liberties than men's":
The fact that women are vulnerable to attack means we cannot have it all. We cannot walk at night across an unlit campus or down a back alley, without incurring real danger. These are things every woman should be able to do, but "shoulds" belong in a Utopian world. They belong in a world where you drop your wallet in a crowd and have it returned, complete with credit cards and cash. A world in which unlocked Porsches are parked in the inner city. And children can be left unattended in the park. This is not the reality that confronts and confines us. 103
The flight from reality of the rape-is-not-sex doctrine warps not just advice to women but policies for deterring rapists. Some prison systems put sex offenders in group therapy and psychodrama sessions designed to uproot experiences of childhood abuse. The goal is to convince the offenders that aggression against women is a way of acting out anger at their mothers, fathers, and society. (A sympathetic story in the Boston Globe concedes that "there is no way to know what the success rate of [the] therapy is. ")104 Another program reeducates batterers and rapists with "pro-feminist therapy" consisting of lectures on patriarchy, heterosexism, and the connections between domestic violence and racial oppression. In an article entitled "The Patriarchy Made Me Do It," the psychiatrist Sally Satel comments, "While it's tempting to conclude that perhaps pro-feminist 'therapy' is just what a violent man deserves, the tragic fact is that truly victimized women are put in even more danger when their husbands undergo a worthless treatment. "105 Savvy offenders who learn to mouth the right psychobabble or feminist slogans can be seen as successfully treated, which can win them earlier release and the opportunity to prey on women anew. {371}
In his thoughtful review, Jones explores how the legal issues surrounding rape can be clarified by a more sophisticated understanding that does not rule the sexual component out of bounds. One example is "chemical castration," voluntary injections of the drug Depo-Provera, which inhibits the release of androgens and reduces the offender's sex drive. It is sometimes given to offenders who are morbidly obsessed with sex and compulsively commit crimes such as rape, indecent exposure, and child abuse. Chemical castration can cut recidivism rates dramatically -- in one study, from 46 percent to 3 percent. Use of the drug certainly raises serious constitutional issues about privacy and punishment, which biology alone cannot decide. But the issues become cloudier, not clearer, when commentators declare a priori that "castration will not work because rape is not a crime about sex, but rather a crime about power and violence. "
Jones is not advocating chemical castration (and neither am I). He is asking people to look at all the options for reducing rape and to evaluate them carefully and with an open mind. Anyone who is incensed by the very idea of mentioning rape and sex in the same breath should read the numbers again. If a policy is rejected out of hand that can reduce rape by a factor of fifteen, then many women will be raped who otherwise might not have been. People may have to decide which they value more, an ideology that claims to advance the interests of the female gender or what actually happens in the world to real women.
~
Despite all the steam coming out of people's ears in the modern debate on the sexes, there are wide expanses of common ground. No one wants to accept sex discrimination or rape. No one wants to turn back the clock and empty the universities and professions of women, even if that were possible. No reasonable person can deny that the advances in the freedom of women during the past century are an incalculable enrichment of the human condition. All the more reason not to get sidetracked by emotionally charged but morally irrelevant red herrings.
The sciences of human nature can strengthen the interests of women by separating those herrings from the truly important goals. Feminism as a movement for political and social equity is important, but feminism as an academic clique committed to eccentric doctrines about human nature is not. Eliminating discrimination against women is important, but
? ? ? ? ? ? believing that women and men are born with indistinguishable minds is not. Freedom of choice is important, but ensuring that women make up exactly 50 percent of all professions is not. And eliminating sexual assaults is important, but advancing the theory that rapists are doing their part in a vast male conspiracy is not.
<< {372} >> Chapter 19
Children
"The nature-nurture debate is over. " So begins a recent article with a title -- "Three Laws of Behavior Genetics and What They Mean" -- as audacious as its opening sentence. 1 The nature-nurture debate is, of course, far from over when it comes to identifying the endowment shared by all human beings and understanding how it allows us to learn, which is the main topic of the preceding chapters. But when it comes to the question of what makes people within the mainstream of a society different from one another -- whether they are smarter or duller, nicer or nastier, bolder or shyer -- the nature-nurture debate, as it has been played out for millennia, really is over, or ought to be.
In announcing that the nature-nurture debate is over, the psychologist Eric Turkheimer was not just using the traditional mule-trainer's technique of getting his subjects' attention, namely whacking them over the head with a two- by-four. He was summarizing a body of empirical results that are unusually robust by the standards of psychology. They have been replicated in many studies, several countries, and over four decades. As the samples grew (often to many thousands), the tools were improved, and the objections were addressed, the results, like the Star-Spangled Banner, were still there.
The three laws of behavioral genetics may be the most important discoveries in the history of psychology. Yet most psychologists have not come to grips with them, and most intellectuals do not understand them, even when they have been explained in the cover stories of newsmagazines. It is not because the laws are abstruse: each can be stated in a sentence, without mathematical paraphernalia. Rather, it is because the laws run roughshod over the Blank Slate, and the Blank Slate is so entrenched that many intellectuals cannot comprehend an alternative to it, let alone argue about whether it is right or wrong.
Here are the three laws: {373}
? The First Law: All human behavioral traits are heritable.
? The Second Law: The effect of being raised in the same family is smaller than the effect of the genes. ? The Third Law: A substantial portion of the variation in complex human behavioral traits is not accounted for by the effects of genes or families.
The laws are about what make us what we are (compared with our compatriots) and thus they are about the forces that impinge on us in childhood, the stage of life in which it is thought that our intellects and personalities are formed. "Just as the twig is bent, the tree's inclined," wrote Alexander Pope. "The child is father of the man," wrote Wordsworth, echoing Milton's "The childhood shows the man as morning shows the day. " The Jesuits used to say, "Give me the child for the first seven years, and I'll give you the man," and the motto was used as the tag line of the documentary film series by Michael Apted that follows a cohort of British children every seven years (Seven Up, Fourteen Up, and so on). In this chapter I will walk you through the laws and explore what they mean for nature, nurture, and none of the above.
~
The First Law: All human behavioral traits are heritable. Let's begin at the beginning. What is a "behavioral trait"? In many studies it is a stable property of a person that can be measured by standardized psychological tests. Intelligence tests ask people to recite a string of digits backwards, define words like reluctant and remorse, identify what an egg and a seed have in common, assemble four triangles into a square, and extrapolate sequences of geometric patterns. Personality tests ask people to agree or disagree with statements like "Often I cross the street in order not to meet someone I know," "I do not blame a person for taking advantage of someone who lays himself open to it," "Before I do something I try to consider how my friends will react to it," and "People say insulting and vulgar things about me. " It sounds dodgy, but the tests have been amply validated: they give pretty much the same result each time a person is tested, and they statistically predict what they ought to predict reasonably well. IQ tests predict performance in school and on the job, and personality profiles correlate with other people's judgments of the person and with life outcomes such as psychiatric diagnoses, marriage stability, and brushes with the law. 2
In other studies behavior is recorded more directly. Graduate students hang out in a schoolyard with a stopwatch and clipboard observing what the children do. Pupils are rated for aggressiveness by several teachers, and the ratings are
? ? ? ? ? ? ? ? averaged. People report how much television they watch or how many cigarettes they smoke. Researchers tally cut- and-dried outcomes such as high school graduation rates, criminal convictions, or divorces.
Once the measurements are made, the variance of the sample may be {374} calculated: the average squared deviation of each person's score from the group mean. The variance is a number that captures the degree to which the members of a group differ from one another. For example, the variance in weight in a sample of Labrador retrievers will be smaller than the variance in weight in a sample that contains dogs of different breeds. Variance can be carved into pieces. It is mathematically meaningful to say that a certain percentage of the variance in a group overlaps with one factor (perhaps, though not necessarily, its cause), another percentage overlaps with a second factor, and so on, the percentages adding up to 100. The degree of overlap may be measured as a correlation coefficient, a number between -1 and +1 that captures the degree to which people who are high on one measurement are also high on another measurement. It is used in behavioral genetic research as an estimate of the proportion of variance accounted for by some factor. 3
Heritability is the proportion of variance in a trait that correlates with genetic differences. It can be measured in several ways. 4 The simplest is to take the correlation between identical twins who were separated at birth and reared apart. They share all their genes and none of their environment (relative to the variation among environments in the sample), so any correlation between them must be an effect of their genes. Alternatively, one can compare identical twins reared together, who share all their genes and most of their environment, with fraternal twins reared together, who share half their genes and most of their environment (to be exact, they share half of the genes that vary among the people within the sample -- obviously they share all the genes that are universal across the human species). If the correlation is higher for pairs of identical twins, it presumably reflects an effect of the extra genes they have in common. The bigger the difference between the two correlations, the higher the heritability estimate. Yet another technique is to compare biological siblings, who share half their genes and most of their environment, with adoptive siblings, who share none of their genes (among those that vary) and most of their environment.
The results come out roughly the same no matter what is measured or how it is measured. Identical twins reared apart are highly similar; identical twins reared together are more similar than fraternal twins reared together; biological siblings are far more similar than adoptive siblings. 5 All this translates into substantial heritability values, generally between . 25 and . 75. A conventional summary is that about half of the variation in intelligence, personality, and life outcomes is heritable -- a correlate or an indirect product of the genes. It's hard to be much more precise than that, because heritability values vary within this range for a number of reasons. 6 One is whether measurement error (random noise) is included in the total variance to be explained or is estimated and pulled out of the equation. Another is whether all the effects of the genes are being estimated or only the additive effects: the ones that exert the same {375} influence regardless of the person's other genes (in other words, the genes for traits that breed true). A third is how much variation there was in the sample to begin with: samples with homogeneous environments give large heritability estimates, those with varied environments give smaller ones. A fourth is when in the person's lifetime a trait is measured. The heritability of intelligence, for example, increases over the lifespan, and can be as high as . 8 late in life. 7 Forget "As the twig is bent"; think "Omigod, I'm turning into my parents! "
"All traits are heritable" is a bit of an exaggeration, but not by much. 8 Concrete behavioral traits that patently depend on content provided by the home or culture are, of course, not heritable at all: which language you speak, which religion you worship in, which political party you belong to. But behavioral traits that reflect the underlying talents and temperaments are heritable: how proficient with language you are, how religious, how liberal or conservative. General intelligence is heritable, and so are the five major ways in which personality can vary (summarized by the acronym OCEAN): openness to experience, conscientiousness, extroversion-introversion, antagonism-agreeableness, and neuroticism. And traits that are surprisingly specific turn out to be heritable, too, such as dependence on nicotine or alcohol, number of hours of television watched, and likelihood of divorcing. Finally there are the Mallifert brothers in Chas Addams's patent office and their real-world counterparts: the identical twins separated at birth who both grew up to be captains of their volunteer fire departments, who both twirled their necklaces when answering questions, or who both told the researcher picking them up at the airport (separately) that a wheel bearing in his car needed to be replaced.
I once watched an interview in which Marlon Brando was asked about the childhood influences that made him an actor. He replied that identical twins separated at birth may both use the same hair tonic, smoke the same brand of cigarettes, vacation on the same beach, and so on. The interviewer, Connie Chung, pretended to snore as if she were sitting through a boring lecture, not realizing that he was answering her question -- or, more accurately, explaining why he couldn't answer it. As long as the heritability of talents and tastes is not zero, none of us has any way of knowing whether a trait has been influenced by our genes, our childhood experiences, both, or neither. Chung is not alone in her failure to understand this point. The First Law implies that any study that measures something in parents and something in their biological children and then draws conclusions about the effects of parenting is worthless,
? ? ? ? ? ? ? ? because the correlations may simply reflect their shared genes (aggressive parents may breed aggressive children, talkative parents talkative children). But these expensive studies continue to be done and continue to be translated into parenting advice as if the heritability of all traits were zero. Perhaps Brando should be asked to serve on grant review panels.
Behavioral genetics does have its critics, who have tried to find alternative {376} interpretations for the First Law. Perhaps children separated at birth are deliberately placed in similar adoptive families. Perhaps they have contact with each other during their separation. Perhaps parents expect identical twins to be more alike and so treat them more alike. Twins share a womb, not just their genes, and identical twins sometimes share a chorion (the membrane surrounding the fetus) and a placenta as well. Perhaps it is their shared prenatal experience, not their shared genes, that makes them more alike.
These possibilities have been tested, and though in some cases they may knock down a heritability estimate by a few points, they cannot reduce it by much. 9 The properties of adoptive parents and homes have been measured (their education, socioeconomic status, personalities, and so on), and they are not homogeneous enough to force identical twins into the same personalities and temperaments. 10 Identical twins are not earmarked for homes that both encourage twirling necklaces or sneezing in elevators. More important, the homes of identical twins who were separated at birth are no more similar than the homes of fraternal twins who were separated at birth, yet the identical twins are far more similar. 11 And most important of all, differences in home environments do not produce differences in grown children's intelligence and personality anyway (as we shall see in examining the Second Law), so the argument is moot.
As for contact between separated twins, it is unlikely that an occasional encounter between two people could revamp their personality and intelligence, but in any case the amount of contact turns out to have no correlation with the twins' degree of similarity. 12 What about the expectations of parents, friends, and peers? A neat test is provided by identical twins who are mistakenly thought to be fraternal until a genetic test shows otherwise. If it is expectations that make identical twins alike, these twins should not be alike; if it is the genes, they should be. In fact the twins are as alike as when the parents know they are identical. 13 And direct measures of how similarly twins are treated by their parents do not correlate with measures of how similar they are in intelligence or personality. 14 Finally, sharing a placenta can make identical twins more different, not just more similar (since one twin can crowd out the other), which is why studies have shown little or no consistent effect of sharing a placenta. 15 But even if it were to make them more similar, the inflation of heritability would be modest. As the behavioral geneticist Matt McGue noted . of a recent mathematical model that tried to use prenatal effects to push down heritability estimates as much as possible, "That the IQ debate now centers on whether IQ is 50% or 70% heritable is a remarkable indication of how the nature- nurture debate has shifted over the past two decades. "16 In any case, studies comparing adoptees with biological siblings don't look at twins at all, and they come to the same conclusions as the twin studies, so no peculiarity of twinhood is likely to overturn the First Law. {377}
Behavioral genetic methods do have three built-in limitations. First, studies of twins, siblings, and adoptees can help explain what makes people different, but they cannot explain what people have in common, that is, universal human nature. To say that the heritability of intelligence is . 5, for example, does not imply that half of a person's intelligence is inherited (whatever that would mean); it implies only that half of the variation among people is inherited. Behavioral genetic studies of pathological conditions, such as those discussed in Chapters 3 and 4, can shed light on universal human nature, but they are not relevant to the topics of this chapter.
Second, behavioral genetic methods address variation within the group of people being examined, not variation between groups of people. If the twins or adoptees in a sample are all middle-class American whites, a heritability estimate can tell us about why middle-class American whites differ from other-middle-class American whites, but not why the middle class differs from the lower or upper class, why Americans differ from non-Americans, or why whites differ from Asians or blacks.
Third, behavioral genetic methods can show only that traits correlate with genes, not that they are directly caused by them. The methods cannot distinguish traits that are relatively direct products of the genes -- the result of genes that affect the wiring or metabolism of the brain -- from traits that are highly indirect products, say, the result of having genes for a certain physical appearance. We know that tall men on average are promoted in their jobs more rapidly than short men, and that attractive people on average are more assertive than unattractive ones. 17 (In one experiment, subjects undergoing a fake interview had to cool their heels when the interviewer was called out of the room by a staged interruption. The plain-looking subjects waited nine minutes before complaining; the attractive ones waited three minutes and twenty seconds. )18 Presumably people defer to tall and good-looking people, and that makes them more successful and entitled. Height and looks are obviously heritable, so if we didn't know about the effects of looks, we might think that these people's success comes directly from genes for ambition and assertiveness instead of
? ? ? ? ? ? ? ? ? ? ? ? ? ? coming indirectly from genes for long legs or a cute nose. The moral is that heritability always has to be interpreted in the light of all the evidence; it does not wear its meaning on its sleeve. That having been said, we know that the heritability of personality cannot, in fact, be reduced to genes for appearance. The effects of looks on personality are small and limited; blond jokes notwithstanding, not all attractive women are vain and entitled. The heritability of personality traits, in contrast, is large and pervasive, too large to be explained away as a by-product of looks. 19 And as we saw in Chapter 3, personality traits can in some cases be tied to actual genes with products in the nervous system. With the completion of the Human Genome Project, it is likely that geneticists soon will be discovering more of those linkages. {378}
The First Law is a pain in the neck for radical scientists, who have tried unsuccessfully to discredit it. In 1974, Leon Kamin wrote that "there exist no data which should lead a prudent man to accept the hypothesis that IQ test scores are in any degree heritable," a conclusion he reiterated with Lewontin and Rose a decade later. 20 Even in the 1970s the argument was tortuous, but by the 1980s it was desperate and today it is a historical curiosity. 21 As usual, the attacks have not always come in dispassionate scholarly analyses. Thomas Bouchard, who directed the first large- scale study of twins reared apart, is one of the pioneers of the study of the genetics of personality. Campus activists at the University of Minnesota distributed handouts calling him a racist and linking him to "German fascism," spray- painted slogans calling him a Nazi, and demanded that he be fired. The psychologist Barry Mehler accused him of "rehabilitating" the work of Josef Mengele, the doctor who tormented twins in the Nazi death camps under the guise of research. As usual, the charges were unfair not just intellectually but personally: far from being a fascist, Bouchard was a participant in the Berkeley Free Speech Movement of the 1960s, was briefly jailed for his activism, and says he would do it again today. 22
These attacks are transparently political and easy to discount. More pernicious is the way that the First Law is commonly interpreted: "So you're saying it's all in the genes," or, more angrily, "Genetic determinism! " I have already commented on this odd reflex in modern intellectual life: when it comes to genes, people suddenly lose their ability to distinguish 50 percent from 100 percent, "some" from "all," "affects" from "determines. " The diagnosis for this intellectual crippling is clear: if the effects of the genes must, on theological grounds, be zero, then all nonzero values are equivalently heretical.
But the worst fallout from the Blank Slate is not that people misunderstand the effects of the genes. It is that they misunderstand the effects of the environment.
~
The Second Law: The effect of being raised in the same family is smaller than the effect of the genes. By now you appreciate that our genes play a role in making us different from our neighbors, and that our environments play an equally important role. At this point everyone draws the same conclusion. We are shaped both by our genes and by our family upbringing: how our parents treated us and what kind of home we grew up in.
Not so fast. Behavioral genetics allows us to distinguish two very different ways in which our environments might affect us. 23 The shared environment is what impinges on us and our siblings alike: our parents, our home life, and our
neighborhood (as compared with other parents and neighborhoods in the sample). The nonshared or unique environment is everything else: anything that impinges on one sibling but not another, including parental favoritism (Mom always liked you best), the presence of the other siblings, unique {379} experiences like falling off a bicycle or being infected by a virus, and for that matter anything that happens to us over the course of our lives that does not necessarily happen to our siblings.
The effects of the shared environment can be measured in twin studies by subtracting the heritabihty value from the correlation between the identical twins. The rationale is that identical twins are alike (measured by the correlation) because of their shared genes (measured by the heritabihty) and their shared environment, so the effects of the shared environment can be estimated by subtracting the heritabihty from the correlation. Alternatively, the effects can be estimated in adoption studies simply by looking at the correlation between two adoptive siblings: they do not share genes, so any similarities (relative to the sample) must come from the experiences they shared growing up in the same home. A third technique is to compare the correlation between siblings reared together (who share genes and a home environment) with the correlation between siblings reared apart (who share only genes).
The effects of the unique environment can be measured by subtracting the correlation between identical twins (who share genes and an environment) from 1 (which is the sum of the effects of the genes, the shared environment, and the unique environment). By the same reasoning, it can be measured in adoption studies by subtracting the heritabihty estimate and the shared-environment estimate from 1. In practice all these calculations are more complicated, because they may try to account for nonadditive effects, where the whole is not the sum of the parts, and for noise in the measurements. But you now have the basic logic behind them.
So what do we find? The effects of shared environment are small (less than 10 percent of the variance), often not
? ? ? ? ? ? ? ?
Finally, think about the humanity of the picture that the gender-feminist theory has painted. As the equity feminist Wendy McElroy points out, the theory holds that "even the most loving and gentle husband, father, and son is a beneficiary of the rape of women they love. No ideology that makes such vicious accusations against men as a class can heal any wounds. It can only provoke hostility in return. "86 {364}
~
Does one need scientific methodology in order to conclude that the anti-female propaganda that permeates our nation's cultural output promotes a climate in which acts of sexual hostility directed against women are not only tolerated but ideologically encouraged?
? ? ? ? Brownmiller asked a revealing rhetorical question:
McElroy responded: "The answer is a clear and simple 'yes. ' One needs scientific methodology to verify any
empirical claim. " And she called attention to the consequences of Brownmiller's attitude: "One of the casualties of the new dogma on rape has been research. It is no longer 'sexually correct' to conduct studies on the causes of rape, because -- as any right-thinking person knows -- there is only one cause: patriarchy. Decades ago, during the heyday of liberal feminism and sexual curiosity, the approach to research was more sophisticated. "87 McElroy's suspicions are borne out by a survey of published "studies" of rape that found that fewer than one in ten tested hypotheses or used scientific methods. 88
Scientific research on rape and its connections to human nature was thrown into the spotlight in 2000 with the publication of A Natural History of Rape. Thornhill and Palmer began with a basic observation: a rape can result in a conception, which could propagate the genes of the rapist, including any genes that had made him likely to rape. Therefore, a male psychology that included a capacity to rape would not have been selected against, and could have been selected for. Thornhill and Palmer argued that rape is unlikely to be a typical mating strategy because of the risk of injury at the hands of the victim and her relatives and the risk of ostracism from the community. But it could be an opportunistic tactic, becoming more likely when the man is unable to win the consent of women, alienated from a community (and thus undeterred by ostracism), and safe from detection and punishment (such as in wartime or pogroms). Thornhill and Palmer then outlined two theories. Opportunistic rape could be a Darwinian adaptation that was specifically selected for, as in certain insects that have an appendage with no function other than restraining a female during forced copulation. Or rape could be a by-product of two other features of the male mind: a desire for sex and a capacity to engage in opportunistic violence in pursuit of a goal. The two authors disagreed on which hypothesis was better supported by the data, and they left that issue unresolved.
No honest reader could conclude that the authors think rape is "natural" in the vernacular sense of being welcome or unavoidable. The first words of the book are, "As scientists who would like to see rape eradicated from human
life . . . ," which are certainly not the words of people who think it is inevitable. Thornhill and Palmer discuss the environmental circumstances that {365} affect the likelihood of rape, and they offer suggestions on how to reduce it. The idea that most men have the capacity to rape works, if anything, in the interests of women, because it calls for vigilance against acquaintance rape, marital rape, and rape during societal breakdowns. Indeed, the analysis jibes with Brownmiller's own data that ordinary men, including "nice" American boys in Vietnam, may rape in wartime. For that matter, Thornhill and Palmer's hypothesis that rape is on a continuum with the rest of male sexuality makes them strange allies with the most radical gender feminists, such as Catharine MacKinnon and Andrea Dworkin, who said that "seduction is often difficult to distinguish from rape. In seduction, the rapist often bothers to buy a bottle of wine. "89
Most important, the book focuses in equal part on the pain of the victims. (Its draft title was Why Men Rape, Why Women Suffer. ) Thornhill and Palmer explain in Darwinian terms why females throughout the animal kingdom resist being forced into sex, and argue that the agony that rape victims feel is deeply rooted in women's nature. Rape subverts female choice, the core of the ubiquitous mechanism of sexual selection. By choosing the male and the circumstances for sex, a female can maximize the chances that her offspring will be fathered by a male with good genes, a willingness and ability to share the responsibility of rearing the offspring, or both. As John Tooby and Leda Cosmides have put it, this ultimate (evolutionary) calculus explains why women evolved "to exert control over their own sexuality, over the terms of their relationships, and over the choice of which men are to be the fathers of their children. " They resist being raped, and they suffer when their resistance fails, because "control over their sexual choices and relationships was wrested from them. "90
Thornhill and Palmer's theory reinforces many points of an equity-feminist analysis. It predicts that from the woman's point of view, rape and consensual sex are completely different. It affirms that women's repugnance toward rape is not a symptom of neurotic repression, nor is it a social construct that could easily be the reverse in a different culture. It predicts that the suffering caused by rape is deeper than the suffering caused by other physical traumas or body violations. That justifies our working harder to prevent rape, and punishing the perpetrators more severely, than we do for other kinds of assault. Compare this analysis with the dubious claim by two gender feminists that an aversion to rape has to be pounded into women by every social influence they can think of:
Female fear. . . [results] not only from women's personal backgrounds but from what women as a group have imbibed from history, religion, culture, social institutions, and everyday social interactions. Learned early in life, female fear is continually reinforced by such {366} social institutions as the school, the church, the law, and the press. Much is also learned from parents, siblings, teachers, and friends. 91
But despite the congeniality of their analysis to women's interests, Thornhill and Palmer had broken a taboo, and the response was familiar: there were demonstrations, disruptions of lectures, and invective that would curdle your hair, as the popular malaprop has it. "Latest nauseating scientific theory" was a typical reaction, and radical scientists
? ? ? ? ? ? ? applied their usual standards of accuracy to denounce it. Hilary Rose, discussing a presentation of the theory by another biologist, wrote, "The sociobiologist David Barash's appeal in defense of his misogynist claims that men are naturally predisposed to rape, 'If Nature is sexist don't blame her sons,' can no longer plug into the old deference to science as the view from nowhere. "92 Barash, of course, had said no such thing; he had referred to rapists as criminals who should be punished. The science writer Margaret Wertheim began her review of Thornhill and Palmer's book by calling attention to a recent epidemic of rape in South Africa. 93 Pitting the theory that rape is "a byproduct of social conditioning and chaos" against the theory that rape has evolutionary and genetic origins, she sarcastically wrote that if the latter were true, "South Africa must be a hothouse for such genes. " Two slurs for the price of one: the statement puts Thornhill and Palmer on the simplistic side of a false dichotomy (in fact, they devote many pages to the social conditions fostering rape) and slips in the innuendo that their theory is racist, too. The psychologist Geoffrey Miller, in his own mixed review of the book, diagnosed the popular reaction:
The Natural History of Rape has already suffered the worst possible fate for a popular science book. Like The Descent of Man and The Bell Curve, it has become an ideological touchstone. People who wish to demonstrate their sympathy for rape victims and women in general have already learned that they must dismiss this book as sexist, reactionary pseudo-science. News stories that treat the book as a symptom of chauvinist cultural decay have greatly outnumbered reviews that assess it as science. Viewed sociologically, turning books into ideological touchstones can be useful. People can efficiently sort themselves out into like-minded cliques without bothering to read or think. However, there can be more to human discourse than ideological self-advertisement. 94
It's unfortunate that Thornhill and Palmer themselves set up a dichotomy between the theory that rape is an adaptation (a specifically selected sexual strategy) and the theory that it is a by-product (a consequence of using violence in general), because it diverted attention from the more basic claim that rape has something to do with sex. I think their dichotomy is drawn too {367} sharply. Male sexuality may have evolved in a world in which women were more discriminating than men about partners and occasions for sex. That would have led men to treat female reluctance as an obstacle to be overcome. (Another way to put it is that one can imagine a species in which the male could become sexually interested only if he detected reciprocal signs of interest on the part of the female, but that humans do not appear to be such a species. ) How the woman's reluctance is overcome depends on the rest of the man's psychology and on his assessment of the circumstances. His usual tactics may include being kind, persuading the woman of his good intentions, and offering the proverbial bottle of wine, but may become increasingly coercive as certain risk factors are multiplied in: the man is a psychopath (hence insensitive to the suffering of others), an outcast (hence immune to ostracism), a loser (with no other means to get sex), or a soldier or ethnic rioter who considers an enemy subhuman and thinks he can get away with it. Certainly most men in ordinary circumstances do not harbor a desire to rape. According to surveys, violent rape is unusual in pornography and sexual fantasies, and according to laboratory studies of men's sexual arousal, depictions of actual violence toward a woman or signs of her pain and humiliation are a turnoff. 95
What about the more basic question of whether the motives of rapists include sex? The gender-feminist argument that they do not points to the rapists who target older, infertile women, those who suffer from sexual dysfunction during the rape, those who coerce nonreproductive sexual acts, and those who use a condom. The argument is unconvincing for two reasons. First, these examples make up a minority of rapes, so the argument could be turned around to show that most rapes do have a sexual motive. And all these phenomena occur with consensual sex, too, so the argument leads to the absurdity that sex itself has nothing to do with sex. And date rape is a particularly problematic case for the not-sex theory. Most people agree that women have the right to say no at any point during sexual activity, and that if the man persists he is a rapist -- but should we also believe that his motive has instantaneously changed from wanting sex to oppressing women?
On the other side there is an impressive body of evidence (reviewed more thoroughly by the legal scholar Owen Jones than by Thornhill and Palmer) that the motives for rape overlap with the motives for sex:96
? Coerced copulation is widespread among species in the animal kingdom, suggesting that it is not selected against and may sometimes be selected for. It is found in many species of insects, birds, and mammals, including our relatives the orangutans, gorillas, and chimpanzees.
? Rape is found in all human societies.
? Rapists generally apply as much force as is needed to coerce the victim into sex. They rarely inflict a serious or fatal injury, which would preclude {368} conception and birth. Only 4 percent of rape victims sustain serious injuries, and fewer than one in five hundred is murdered.
? Victims of rape are mostly in the peak reproductive years for women, between thirteen and thirty-
? ? ? ? ? ? ? five, with a mean in most data sets of twenty-four. Though many rape victims are classified as children (under the age of sixteen), most of these are adolescents, with a median age of fourteen. The age distribution is very different from that of victims of other violent crimes, and is the opposite of what would happen if rape victims were picked for their physical vulnerability or by their likelihood of holding positions of power.
? Victims of rape are more traumatized when the rape can result in a conception. It is most psychologically painful for women in their fertile years, and for victims of forced intercourse as opposed to other forms of rape.
? Rapists are not demographically representative of the male gender. They are overwhelmingly young men, the age of the most intense sexual competitiveness. The young males who allegedly have been "socialized" to rape mysteriously lose that socialization as they get older.
? Though most rapes do not result in conception, many do. About 5 percent of rape victims of reproductive age become pregnant, resulting in more than 32,000 rape-related pregnancies in the United States each year. (That is why abortion in the case of rape is a significant issue. ) The proportion would have been even higher in prehistory, when women did not use long-term contraception. 97 Brownmiller wrote that biological theories of rape are "fanciful" because "in terms of reproductive strategy, the hit or miss ejaculations of a single-strike rapist are a form of Russian roulette compared to ongoing consensual mating. "98 But ongoing consensual mating is not an option for every male, and dispositions that resulted in hit-or-miss sex could be evolutionarily more successful than dispositions that resulted in no sex at all. Natural selection can operate effectively with small reproductive advantages, as little as 1 percent.
~
The payoff for a reality-based understanding of rape is the hope of reducing or eliminating it. Given the theories on the table, the possible sites for levers of influence include violence, sexist attitudes, and sexual desire.
Everyone agrees that rape is a crime of violence. Probably the biggest amplifier of rape is lawlessness. The rape and abduction of women is often a goal of raiding in non-state societies, and rape is common in wars between states and riots between ethnic groups. In peacetime, the rates of rape tend to track rates of other violent crime. In the United States, for example, the rate of forcible rape went up in the 1960s and down in the 1990s, together with the rates of other violent crimes. 99 Gender feminists blame violence against women on civilization and social institutions, but this is exactly backwards. {369} Violence against women flourishes in societies that are outside the reach of civilization, and erupts whenever civilization breaks down.
Though I know of no quantitative studies, the targeting of sexist attitudes does not seem to be a particularly promising avenue for reducing rape, though of course it is desirable for other reasons. Countries with far more rigid gender roles than the United States, such as Japan, have far lower rates of rape, and within the United States the sexist 1950s were far safer for women than the more liberated 1970s and 1980s. If anything, the correlation might go in the opposite direction. As women gain greater freedom of movement because they are independent of men, they will more often find themselves in dangerous situations.
What about measures that focus on the sexual components of rape? Thornhill and Palmer suggested that teenage boys be forced to take a rape-prevention course as a condition for obtaining a driver's license, and that women should be reminded that dressing in a sexually attractive way may increase their risk of being raped. These untested prescriptions are an excellent illustration of why scientists should stay out of the policy business, but they don't deserve the outrage that followed. Mary Koss, described as an authority on rape, said, "The thinking is absolutely unacceptable in a democratic society. " (Note the psychology of taboo -- not only is their suggestion wrong, but merely thinking it is "absolutely unacceptable. ") Koss continues, "Because rape is a gendered crime, such recommendations harm equality. They infringe more on women's liberties than men's. "100
One can understand the repugnance at any suggestion that an attractively dressed woman excites an irresistible impulse to rape, or that culpability in any crime should be shifted from the perpetrator to the victim. But Thornhill and Palmer said neither of those things. They were offering a recommendation based on prudence, not an assignment of blame based on justice. Of course women have a right to dress in any way they please, but the issue is not what women have the right to do in a perfect world but how they can maximize their safety in this world. The suggestion that women in dangerous situations be mindful of reactions they may be eliciting or signals they may inadvertently be sending is just common sense, and it's hard to believe any grownup would think otherwise -- unless she has been indoctrinated by the standard rape-prevention programs that tell women that "sexual assault is not an act of sexual gratification" and that "appearance and attractiveness are not relevant. "101 Equity feminists have called attention to
? ? ? ? ? ? the irresponsibility of such advice, in terms far harsher than anything by Thornhill and Palmer. Paglia, for example, wrote:
For a decade, feminists have drilled their disciples to say, "Rape is a crime of violence but not sex. " This sugar-coated Shirley Temple {370} nonsense has exposed young women to disaster. Misled by feminism, they do not expect rape from the nice boys from good homes who sit next to them in class. . . . These girls say, "Well, I should be able to get drunk at a fraternity party and go upstairs to a guy's room without anything happening. " And I say, "Oh, really? And when you drive your car to New York City, do you leave your keys on the hood? " My point is that if your car is stolen after you do something like that, yes, the police should pursue the thief and he should be punished. But at the same time, the police -- and I -- have the right to say to you, "You stupid idiot, what the hell were you thinking? "102
Similarly, McElroy points out the illogic of arguments like Koss's that women should not be given practical advice that "infringes more on women's liberties than men's":
The fact that women are vulnerable to attack means we cannot have it all. We cannot walk at night across an unlit campus or down a back alley, without incurring real danger. These are things every woman should be able to do, but "shoulds" belong in a Utopian world. They belong in a world where you drop your wallet in a crowd and have it returned, complete with credit cards and cash. A world in which unlocked Porsches are parked in the inner city. And children can be left unattended in the park. This is not the reality that confronts and confines us. 103
The flight from reality of the rape-is-not-sex doctrine warps not just advice to women but policies for deterring rapists. Some prison systems put sex offenders in group therapy and psychodrama sessions designed to uproot experiences of childhood abuse. The goal is to convince the offenders that aggression against women is a way of acting out anger at their mothers, fathers, and society. (A sympathetic story in the Boston Globe concedes that "there is no way to know what the success rate of [the] therapy is. ")104 Another program reeducates batterers and rapists with "pro-feminist therapy" consisting of lectures on patriarchy, heterosexism, and the connections between domestic violence and racial oppression. In an article entitled "The Patriarchy Made Me Do It," the psychiatrist Sally Satel comments, "While it's tempting to conclude that perhaps pro-feminist 'therapy' is just what a violent man deserves, the tragic fact is that truly victimized women are put in even more danger when their husbands undergo a worthless treatment. "105 Savvy offenders who learn to mouth the right psychobabble or feminist slogans can be seen as successfully treated, which can win them earlier release and the opportunity to prey on women anew. {371}
In his thoughtful review, Jones explores how the legal issues surrounding rape can be clarified by a more sophisticated understanding that does not rule the sexual component out of bounds. One example is "chemical castration," voluntary injections of the drug Depo-Provera, which inhibits the release of androgens and reduces the offender's sex drive. It is sometimes given to offenders who are morbidly obsessed with sex and compulsively commit crimes such as rape, indecent exposure, and child abuse. Chemical castration can cut recidivism rates dramatically -- in one study, from 46 percent to 3 percent. Use of the drug certainly raises serious constitutional issues about privacy and punishment, which biology alone cannot decide. But the issues become cloudier, not clearer, when commentators declare a priori that "castration will not work because rape is not a crime about sex, but rather a crime about power and violence. "
Jones is not advocating chemical castration (and neither am I). He is asking people to look at all the options for reducing rape and to evaluate them carefully and with an open mind. Anyone who is incensed by the very idea of mentioning rape and sex in the same breath should read the numbers again. If a policy is rejected out of hand that can reduce rape by a factor of fifteen, then many women will be raped who otherwise might not have been. People may have to decide which they value more, an ideology that claims to advance the interests of the female gender or what actually happens in the world to real women.
~
Despite all the steam coming out of people's ears in the modern debate on the sexes, there are wide expanses of common ground. No one wants to accept sex discrimination or rape. No one wants to turn back the clock and empty the universities and professions of women, even if that were possible. No reasonable person can deny that the advances in the freedom of women during the past century are an incalculable enrichment of the human condition. All the more reason not to get sidetracked by emotionally charged but morally irrelevant red herrings.
The sciences of human nature can strengthen the interests of women by separating those herrings from the truly important goals. Feminism as a movement for political and social equity is important, but feminism as an academic clique committed to eccentric doctrines about human nature is not. Eliminating discrimination against women is important, but
? ? ? ? ? ? believing that women and men are born with indistinguishable minds is not. Freedom of choice is important, but ensuring that women make up exactly 50 percent of all professions is not. And eliminating sexual assaults is important, but advancing the theory that rapists are doing their part in a vast male conspiracy is not.
<< {372} >> Chapter 19
Children
"The nature-nurture debate is over. " So begins a recent article with a title -- "Three Laws of Behavior Genetics and What They Mean" -- as audacious as its opening sentence. 1 The nature-nurture debate is, of course, far from over when it comes to identifying the endowment shared by all human beings and understanding how it allows us to learn, which is the main topic of the preceding chapters. But when it comes to the question of what makes people within the mainstream of a society different from one another -- whether they are smarter or duller, nicer or nastier, bolder or shyer -- the nature-nurture debate, as it has been played out for millennia, really is over, or ought to be.
In announcing that the nature-nurture debate is over, the psychologist Eric Turkheimer was not just using the traditional mule-trainer's technique of getting his subjects' attention, namely whacking them over the head with a two- by-four. He was summarizing a body of empirical results that are unusually robust by the standards of psychology. They have been replicated in many studies, several countries, and over four decades. As the samples grew (often to many thousands), the tools were improved, and the objections were addressed, the results, like the Star-Spangled Banner, were still there.
The three laws of behavioral genetics may be the most important discoveries in the history of psychology. Yet most psychologists have not come to grips with them, and most intellectuals do not understand them, even when they have been explained in the cover stories of newsmagazines. It is not because the laws are abstruse: each can be stated in a sentence, without mathematical paraphernalia. Rather, it is because the laws run roughshod over the Blank Slate, and the Blank Slate is so entrenched that many intellectuals cannot comprehend an alternative to it, let alone argue about whether it is right or wrong.
Here are the three laws: {373}
? The First Law: All human behavioral traits are heritable.
? The Second Law: The effect of being raised in the same family is smaller than the effect of the genes. ? The Third Law: A substantial portion of the variation in complex human behavioral traits is not accounted for by the effects of genes or families.
The laws are about what make us what we are (compared with our compatriots) and thus they are about the forces that impinge on us in childhood, the stage of life in which it is thought that our intellects and personalities are formed. "Just as the twig is bent, the tree's inclined," wrote Alexander Pope. "The child is father of the man," wrote Wordsworth, echoing Milton's "The childhood shows the man as morning shows the day. " The Jesuits used to say, "Give me the child for the first seven years, and I'll give you the man," and the motto was used as the tag line of the documentary film series by Michael Apted that follows a cohort of British children every seven years (Seven Up, Fourteen Up, and so on). In this chapter I will walk you through the laws and explore what they mean for nature, nurture, and none of the above.
~
The First Law: All human behavioral traits are heritable. Let's begin at the beginning. What is a "behavioral trait"? In many studies it is a stable property of a person that can be measured by standardized psychological tests. Intelligence tests ask people to recite a string of digits backwards, define words like reluctant and remorse, identify what an egg and a seed have in common, assemble four triangles into a square, and extrapolate sequences of geometric patterns. Personality tests ask people to agree or disagree with statements like "Often I cross the street in order not to meet someone I know," "I do not blame a person for taking advantage of someone who lays himself open to it," "Before I do something I try to consider how my friends will react to it," and "People say insulting and vulgar things about me. " It sounds dodgy, but the tests have been amply validated: they give pretty much the same result each time a person is tested, and they statistically predict what they ought to predict reasonably well. IQ tests predict performance in school and on the job, and personality profiles correlate with other people's judgments of the person and with life outcomes such as psychiatric diagnoses, marriage stability, and brushes with the law. 2
In other studies behavior is recorded more directly. Graduate students hang out in a schoolyard with a stopwatch and clipboard observing what the children do. Pupils are rated for aggressiveness by several teachers, and the ratings are
? ? ? ? ? ? ? ? averaged. People report how much television they watch or how many cigarettes they smoke. Researchers tally cut- and-dried outcomes such as high school graduation rates, criminal convictions, or divorces.
Once the measurements are made, the variance of the sample may be {374} calculated: the average squared deviation of each person's score from the group mean. The variance is a number that captures the degree to which the members of a group differ from one another. For example, the variance in weight in a sample of Labrador retrievers will be smaller than the variance in weight in a sample that contains dogs of different breeds. Variance can be carved into pieces. It is mathematically meaningful to say that a certain percentage of the variance in a group overlaps with one factor (perhaps, though not necessarily, its cause), another percentage overlaps with a second factor, and so on, the percentages adding up to 100. The degree of overlap may be measured as a correlation coefficient, a number between -1 and +1 that captures the degree to which people who are high on one measurement are also high on another measurement. It is used in behavioral genetic research as an estimate of the proportion of variance accounted for by some factor. 3
Heritability is the proportion of variance in a trait that correlates with genetic differences. It can be measured in several ways. 4 The simplest is to take the correlation between identical twins who were separated at birth and reared apart. They share all their genes and none of their environment (relative to the variation among environments in the sample), so any correlation between them must be an effect of their genes. Alternatively, one can compare identical twins reared together, who share all their genes and most of their environment, with fraternal twins reared together, who share half their genes and most of their environment (to be exact, they share half of the genes that vary among the people within the sample -- obviously they share all the genes that are universal across the human species). If the correlation is higher for pairs of identical twins, it presumably reflects an effect of the extra genes they have in common. The bigger the difference between the two correlations, the higher the heritability estimate. Yet another technique is to compare biological siblings, who share half their genes and most of their environment, with adoptive siblings, who share none of their genes (among those that vary) and most of their environment.
The results come out roughly the same no matter what is measured or how it is measured. Identical twins reared apart are highly similar; identical twins reared together are more similar than fraternal twins reared together; biological siblings are far more similar than adoptive siblings. 5 All this translates into substantial heritability values, generally between . 25 and . 75. A conventional summary is that about half of the variation in intelligence, personality, and life outcomes is heritable -- a correlate or an indirect product of the genes. It's hard to be much more precise than that, because heritability values vary within this range for a number of reasons. 6 One is whether measurement error (random noise) is included in the total variance to be explained or is estimated and pulled out of the equation. Another is whether all the effects of the genes are being estimated or only the additive effects: the ones that exert the same {375} influence regardless of the person's other genes (in other words, the genes for traits that breed true). A third is how much variation there was in the sample to begin with: samples with homogeneous environments give large heritability estimates, those with varied environments give smaller ones. A fourth is when in the person's lifetime a trait is measured. The heritability of intelligence, for example, increases over the lifespan, and can be as high as . 8 late in life. 7 Forget "As the twig is bent"; think "Omigod, I'm turning into my parents! "
"All traits are heritable" is a bit of an exaggeration, but not by much. 8 Concrete behavioral traits that patently depend on content provided by the home or culture are, of course, not heritable at all: which language you speak, which religion you worship in, which political party you belong to. But behavioral traits that reflect the underlying talents and temperaments are heritable: how proficient with language you are, how religious, how liberal or conservative. General intelligence is heritable, and so are the five major ways in which personality can vary (summarized by the acronym OCEAN): openness to experience, conscientiousness, extroversion-introversion, antagonism-agreeableness, and neuroticism. And traits that are surprisingly specific turn out to be heritable, too, such as dependence on nicotine or alcohol, number of hours of television watched, and likelihood of divorcing. Finally there are the Mallifert brothers in Chas Addams's patent office and their real-world counterparts: the identical twins separated at birth who both grew up to be captains of their volunteer fire departments, who both twirled their necklaces when answering questions, or who both told the researcher picking them up at the airport (separately) that a wheel bearing in his car needed to be replaced.
I once watched an interview in which Marlon Brando was asked about the childhood influences that made him an actor. He replied that identical twins separated at birth may both use the same hair tonic, smoke the same brand of cigarettes, vacation on the same beach, and so on. The interviewer, Connie Chung, pretended to snore as if she were sitting through a boring lecture, not realizing that he was answering her question -- or, more accurately, explaining why he couldn't answer it. As long as the heritability of talents and tastes is not zero, none of us has any way of knowing whether a trait has been influenced by our genes, our childhood experiences, both, or neither. Chung is not alone in her failure to understand this point. The First Law implies that any study that measures something in parents and something in their biological children and then draws conclusions about the effects of parenting is worthless,
? ? ? ? ? ? ? ? because the correlations may simply reflect their shared genes (aggressive parents may breed aggressive children, talkative parents talkative children). But these expensive studies continue to be done and continue to be translated into parenting advice as if the heritability of all traits were zero. Perhaps Brando should be asked to serve on grant review panels.
Behavioral genetics does have its critics, who have tried to find alternative {376} interpretations for the First Law. Perhaps children separated at birth are deliberately placed in similar adoptive families. Perhaps they have contact with each other during their separation. Perhaps parents expect identical twins to be more alike and so treat them more alike. Twins share a womb, not just their genes, and identical twins sometimes share a chorion (the membrane surrounding the fetus) and a placenta as well. Perhaps it is their shared prenatal experience, not their shared genes, that makes them more alike.
These possibilities have been tested, and though in some cases they may knock down a heritability estimate by a few points, they cannot reduce it by much. 9 The properties of adoptive parents and homes have been measured (their education, socioeconomic status, personalities, and so on), and they are not homogeneous enough to force identical twins into the same personalities and temperaments. 10 Identical twins are not earmarked for homes that both encourage twirling necklaces or sneezing in elevators. More important, the homes of identical twins who were separated at birth are no more similar than the homes of fraternal twins who were separated at birth, yet the identical twins are far more similar. 11 And most important of all, differences in home environments do not produce differences in grown children's intelligence and personality anyway (as we shall see in examining the Second Law), so the argument is moot.
As for contact between separated twins, it is unlikely that an occasional encounter between two people could revamp their personality and intelligence, but in any case the amount of contact turns out to have no correlation with the twins' degree of similarity. 12 What about the expectations of parents, friends, and peers? A neat test is provided by identical twins who are mistakenly thought to be fraternal until a genetic test shows otherwise. If it is expectations that make identical twins alike, these twins should not be alike; if it is the genes, they should be. In fact the twins are as alike as when the parents know they are identical. 13 And direct measures of how similarly twins are treated by their parents do not correlate with measures of how similar they are in intelligence or personality. 14 Finally, sharing a placenta can make identical twins more different, not just more similar (since one twin can crowd out the other), which is why studies have shown little or no consistent effect of sharing a placenta. 15 But even if it were to make them more similar, the inflation of heritability would be modest. As the behavioral geneticist Matt McGue noted . of a recent mathematical model that tried to use prenatal effects to push down heritability estimates as much as possible, "That the IQ debate now centers on whether IQ is 50% or 70% heritable is a remarkable indication of how the nature- nurture debate has shifted over the past two decades. "16 In any case, studies comparing adoptees with biological siblings don't look at twins at all, and they come to the same conclusions as the twin studies, so no peculiarity of twinhood is likely to overturn the First Law. {377}
Behavioral genetic methods do have three built-in limitations. First, studies of twins, siblings, and adoptees can help explain what makes people different, but they cannot explain what people have in common, that is, universal human nature. To say that the heritability of intelligence is . 5, for example, does not imply that half of a person's intelligence is inherited (whatever that would mean); it implies only that half of the variation among people is inherited. Behavioral genetic studies of pathological conditions, such as those discussed in Chapters 3 and 4, can shed light on universal human nature, but they are not relevant to the topics of this chapter.
Second, behavioral genetic methods address variation within the group of people being examined, not variation between groups of people. If the twins or adoptees in a sample are all middle-class American whites, a heritability estimate can tell us about why middle-class American whites differ from other-middle-class American whites, but not why the middle class differs from the lower or upper class, why Americans differ from non-Americans, or why whites differ from Asians or blacks.
Third, behavioral genetic methods can show only that traits correlate with genes, not that they are directly caused by them. The methods cannot distinguish traits that are relatively direct products of the genes -- the result of genes that affect the wiring or metabolism of the brain -- from traits that are highly indirect products, say, the result of having genes for a certain physical appearance. We know that tall men on average are promoted in their jobs more rapidly than short men, and that attractive people on average are more assertive than unattractive ones. 17 (In one experiment, subjects undergoing a fake interview had to cool their heels when the interviewer was called out of the room by a staged interruption. The plain-looking subjects waited nine minutes before complaining; the attractive ones waited three minutes and twenty seconds. )18 Presumably people defer to tall and good-looking people, and that makes them more successful and entitled. Height and looks are obviously heritable, so if we didn't know about the effects of looks, we might think that these people's success comes directly from genes for ambition and assertiveness instead of
? ? ? ? ? ? ? ? ? ? ? ? ? ? coming indirectly from genes for long legs or a cute nose. The moral is that heritability always has to be interpreted in the light of all the evidence; it does not wear its meaning on its sleeve. That having been said, we know that the heritability of personality cannot, in fact, be reduced to genes for appearance. The effects of looks on personality are small and limited; blond jokes notwithstanding, not all attractive women are vain and entitled. The heritability of personality traits, in contrast, is large and pervasive, too large to be explained away as a by-product of looks. 19 And as we saw in Chapter 3, personality traits can in some cases be tied to actual genes with products in the nervous system. With the completion of the Human Genome Project, it is likely that geneticists soon will be discovering more of those linkages. {378}
The First Law is a pain in the neck for radical scientists, who have tried unsuccessfully to discredit it. In 1974, Leon Kamin wrote that "there exist no data which should lead a prudent man to accept the hypothesis that IQ test scores are in any degree heritable," a conclusion he reiterated with Lewontin and Rose a decade later. 20 Even in the 1970s the argument was tortuous, but by the 1980s it was desperate and today it is a historical curiosity. 21 As usual, the attacks have not always come in dispassionate scholarly analyses. Thomas Bouchard, who directed the first large- scale study of twins reared apart, is one of the pioneers of the study of the genetics of personality. Campus activists at the University of Minnesota distributed handouts calling him a racist and linking him to "German fascism," spray- painted slogans calling him a Nazi, and demanded that he be fired. The psychologist Barry Mehler accused him of "rehabilitating" the work of Josef Mengele, the doctor who tormented twins in the Nazi death camps under the guise of research. As usual, the charges were unfair not just intellectually but personally: far from being a fascist, Bouchard was a participant in the Berkeley Free Speech Movement of the 1960s, was briefly jailed for his activism, and says he would do it again today. 22
These attacks are transparently political and easy to discount. More pernicious is the way that the First Law is commonly interpreted: "So you're saying it's all in the genes," or, more angrily, "Genetic determinism! " I have already commented on this odd reflex in modern intellectual life: when it comes to genes, people suddenly lose their ability to distinguish 50 percent from 100 percent, "some" from "all," "affects" from "determines. " The diagnosis for this intellectual crippling is clear: if the effects of the genes must, on theological grounds, be zero, then all nonzero values are equivalently heretical.
But the worst fallout from the Blank Slate is not that people misunderstand the effects of the genes. It is that they misunderstand the effects of the environment.
~
The Second Law: The effect of being raised in the same family is smaller than the effect of the genes. By now you appreciate that our genes play a role in making us different from our neighbors, and that our environments play an equally important role. At this point everyone draws the same conclusion. We are shaped both by our genes and by our family upbringing: how our parents treated us and what kind of home we grew up in.
Not so fast. Behavioral genetics allows us to distinguish two very different ways in which our environments might affect us. 23 The shared environment is what impinges on us and our siblings alike: our parents, our home life, and our
neighborhood (as compared with other parents and neighborhoods in the sample). The nonshared or unique environment is everything else: anything that impinges on one sibling but not another, including parental favoritism (Mom always liked you best), the presence of the other siblings, unique {379} experiences like falling off a bicycle or being infected by a virus, and for that matter anything that happens to us over the course of our lives that does not necessarily happen to our siblings.
The effects of the shared environment can be measured in twin studies by subtracting the heritabihty value from the correlation between the identical twins. The rationale is that identical twins are alike (measured by the correlation) because of their shared genes (measured by the heritabihty) and their shared environment, so the effects of the shared environment can be estimated by subtracting the heritabihty from the correlation. Alternatively, the effects can be estimated in adoption studies simply by looking at the correlation between two adoptive siblings: they do not share genes, so any similarities (relative to the sample) must come from the experiences they shared growing up in the same home. A third technique is to compare the correlation between siblings reared together (who share genes and a home environment) with the correlation between siblings reared apart (who share only genes).
The effects of the unique environment can be measured by subtracting the correlation between identical twins (who share genes and an environment) from 1 (which is the sum of the effects of the genes, the shared environment, and the unique environment). By the same reasoning, it can be measured in adoption studies by subtracting the heritabihty estimate and the shared-environment estimate from 1. In practice all these calculations are more complicated, because they may try to account for nonadditive effects, where the whole is not the sum of the parts, and for noise in the measurements. But you now have the basic logic behind them.
So what do we find? The effects of shared environment are small (less than 10 percent of the variance), often not
? ? ? ? ? ? ? ?
