It would seem odd that the hormones that make us male and female in the first place also modulate the characteristically male and female mental traits, both decisively in early brain
development
and in smaller degrees throughout our lives.
Steven-Pinker-The-Blank-Slate 1
?
?
?
?
?
?
?
?
they're not anti-Semitic.
"20 And they have invented a lexicon of epithets for what in any other area would be called disagreement: "backlash," "not getting it," "silencing women," "intellectual harassment.
"21
All this is an essential background to the discussions to come. To say that women and men do not have interchangeable minds, that people have desires other than power, and that motives belong to individual people and not just to entire genders is not to attack feminism or to compromise the interests of women, despite the misconception that gender feminism speaks in their name. All the arguments in the remainder of this chapter have been advanced most forcefully by women.
~
Why are people so afraid of the idea that the minds of men and women are not identical in every respect? Would we really be better off if everyone were like Pat, the androgynous nerd from Saturday Night Live? The fear, of course, is that different implies unequal -- that if the sexes differed in any way, then men would have to be better, or more dominant, or have all the fun.
Nothing could be farther from biological thinking. Trivers alluded to a "symmetry in human relationships," which embraced a "genetic equality of the sexes. "22 From a gene's point of view, being in the body of a male and being in the body of a female are equally good strategies, at least on average (circumstances can nudge the advantage somewhat in either direction). 23 Natural selection thus tends toward an equal investment in the two sexes: equal numbers, an equal complexity of bodies and brains, and equally effective designs for survival. Is it better to be the size of a male baboon and have six-inch canine teeth or to be the size of a female baboon and not have them? Merely to {344} ask the question is to reveal its pointlessness. A biologist would say that it's better to have the male adaptations to deal with male problems and the female adaptations to deal with female problems.
So men are not from Mars, nor are women from Venus. Men and women are from Africa, the cradle of our evolution, where they evolved together as a single species. Men and women have all the same genes except for a handful on the Y chromosome, and their brains are so similar that it takes an eagle-eyed neuroanatomist to find the small differences between them. Their average levels of general intelligence are the same, according to the best psychometric estimates,24 and they use language and think about the physical and living world in the same general way. They feel the same basic emotions, and both enjoy sex, seek intelligent and kind marriage partners, get jealous, make sacrifices for their children, compete for status and mates, and sometimes commit aggression in pursuit of their interests.
But of course the minds of men and women are not identical, and recent reviews of sex differences have converged on some reliable differences. 25 Sometimes the differences are large, with only slight overlap in the bell curves. Men have a much stronger taste for no-strings sex with multiple or anonymous partners, as we see in the almost all-male consumer base for prostitution and visual pornography. 26 Men are far more likely to compete violently, sometimes lethally, with one another over stakes great and small (as in the recent case of a surgeon and an anesthesiologist who came to blows in the operating room while a patient lay on the table waiting to have her gall bladder removed). 27 Among children, boys spend far more time practicing for violent conflict in the form of what psychologists genteelly call "rough-and-tumble play. "28 The ability to manipulate three-dimensional objects and space in the mind also shows a large difference in favor of men. 29
With some other traits the differences are small on average but can be large at the extremes. That happens for two reasons. When two bell curves partly overlap, the farther out along the tail you go, the larger the discrepancies between the groups. For example, men on average are taller than women, and the discrepancy is greater for more extreme values. At a height of five foot ten, men outnumber women by a ratio of thirty to one; at a height of six feet, men outnumber women by a ratio of two thousand to one. Also, confirming an expectation from evolutionary psychology, for many traits the bell curve for males is flatter and wider than the curve for females. That is, there are proportionally more males at the extremes. Along the left tail of the curve, one finds that boys are far more likely to be dyslexic, learning disabled, attention deficient, emotionally disturbed, and mentally retarded (at least for some types of retardation). 30 At the right tail, one finds that in a sample of talented students who score above 700 (out of 800) on the mathematics section of the {345} Scholastic Assessment Test, boys outnumber girls by thirteen to one, even though the scores of boys and girls are similar within the bulk of the curve. 31
With still other traits, the average values for the two sexes differ by smaller amounts and in different directions for different traits. 32 Though men, on average, are better at mentally rotating objects and maps, women are better at
remembering landmarks and the positions of objects. Men are better throwers; women are more dexterous. Men are better at solving mathematical word problems, women at mathematical calculation. Women are more sensitive to sounds and smells, have better depth perception, match shapes faster, and are much better at reading facial expressions and body language. Women are better spellers, retrieve words more fluently, and have a better memory for verbal material.
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Women experience basic emotions more intensely, except perhaps anger. 33 Women have more intimate social relationships, are more concerned about them, and feel more empathy toward their friends, though not toward strangers. (The common view that women are more empathic toward everyone is both evolutionarily unlikely and untrue. ) They maintain more eye contact, and smile and laugh far more often. 34 Men are more likely to compete with one another for status using violence or occupational achievement, women more likely to use derogation and other forms of verbal aggression.
Men have a higher tolerance for pain and a greater willingness to risk life and limb for status, attention, and other dubious rewards. The Darwin Awards, given annually to "the individuals who ensure the long-term survival of our species by removing themselves from the gene pool in a sublimely idiotic fashion," almost always go to men. Recent honorees include the man who squashed himself under a Coke machine after tipping it forward to get a free can, three men who competed over who could stomp the hardest on an antitank mine, and the would-be pilot who tied weather balloons to his lawn chair, shot two miles into the air, and drifted out to sea (earning just an Honorable Mention because he was rescued by helicopter).
Women are more attentive to their infants' everyday cries (though both sexes respond equally to cries of extreme distress) and are more solicitous toward their children in general. 35 Girls play more at parenting and trying on social
roles, boys more at fighting, chasing, and manipulating objects. And men and women differ in their patterns of sexual jealousy, their mate preferences, and their incentives to philander.
Many sex differences, of course, have nothing to do with biology. Hair styles and dress vary capriciously across centuries and cultures, and in recent decades participation in universities, professions, and sports has switched from mostly male to fifty-fifty or mostly female. For all we know, some of the current sex differences may be just as ephemeral. But gender feminists argue {346} that all sex differences, other than the anatomical ones, come from the expectations of parents, playmates, and society. The radical scientist Anne Fausto-Sterling wrote:
The key biological fact is that boys and girls have different genitalia, and it is this biological difference that leads adults to interact differently with different babies whom we conveniently color-code in pink or blue to make it unnecessary to go peering into their diapers for information about gender. 36
But the pink-and-blue theory is becoming less and less credible. Here are a dozen kinds of evidence that suggest that the difference between men and women is more than genitalia-deep.
? Sex differences are not an arbitrary feature of Western culture, like the decision to drive on the left or on the right. In all human cultures, men and women are seen as having different natures. All cultures divide their labor by sex, with more responsibility for childrearing by women and more control of the public and political realms by men. (The division of labor emerged even in a culture where everyone had been committed to stamping it out, the Israeli kibbutz. ) In all cultures men are more aggressive, more prone to stealing, more prone to lethal violence (including war), and more likely to woo, seduce, and trade favors for sex. And in all cultures one finds rape, as well as proscriptions against rape. 37
? Many of the psychological differences between the sexes are exactly what an evolutionary biologist who knew only their physical differences would predict. 38 Throughout the animal kingdom, when the
female has to invest more calories and risk in each offspring (in the case of mammals, through pregnancy and nursing), she also invests more in nurturing the offspring after birth, since it is more costly for a female to replace a child than for a male to replace one. The difference in investment is accompanied by a greater competition among males over opportunities to mate, since mating with many partners is more likely to multiply the number of offspring of a male than the number of offspring of a female. When the average male is larger than the average female (as is true of men and women), it bespeaks an evolutionary history of greater violent competition by males over mating opportunities. Other physical traits of men, such as later puberty, greater adult strength, and shorter lives, also indicate a history of selection for high-stakes competition.
? Many of the sex differences are found widely in other primates, indeed, throughout the mammalian class. 39 The males tend to compete more aggressively and to be more polygamous; the females tend to
invest more in {347} parenting. In many mammals a greater territorial range is accompanied by an enhanced ability to navigate using the geometry of the spatial layout (as opposed to remembering individual landmarks). More often it is the male who has the greater range, and that is true of human hunter-gatherers. Men's advantage in using mental maps and performing 3-D mental rotation may not be a coincidence. 40
? Geneticists have found that the diversity of the DNA in the mitochondria of different people (which men and women inherit from their mothers) is far greater than the diversity of the DNA in Y
? ? ? ? ? ? ? ? ? ? chromosomes (which men inherit from their fathers). This suggests that for tens of millennia men had greater variation in their reproductive success than women. Some men had many descendants and others had none (leaving us with a small number of distinct Y chromosomes), whereas a larger number of women had a more evenly distributed number of descendants (leaving us with a larger number of distinct mitochondrial genomes). These are precisely the conditions that cause sexual selection, in which males compete for opportunities to mate and females choose the best-quality males. 41
? The human body contains a mechanism that causes the brains of boys and the brains of girls to diverge during development. 42 The Y chromosome triggers the growth of testes in a male fetus, which
secrete androgens, the characteristically male hormones (including testosterone). Androgens have lasting effects on the brain during fetal development, in the months after birth, and during puberty, and they have transient effects at other times. Estrogens, the characteristically female sex hormones, also affect the brain throughout life. Receptors for the sex hormones are found in the hypothalamus, the hippocampus, and the amygdala in the limbic system of the brain, as well as in the cerebral cortex.
? The brains of men differ visibly from the brains of women in several ways. 43 Men have larger brains with more neurons (even correcting for body size), though women have a higher percentage of gray matter. (Since men and women are equally intelligent overall, the significance of these differences is unknown. ) The interstitial nuclei in the anterior hypothalamus, and a nucleus of the stria terminalis, also in the hypothalamus, are larger in men; they have been implicated in sexual behavior and aggression. Portions of the cerebral commissures, which link the left and right hemispheres, appear to be larger in women, and their brains may function in a less lopsided manner than men's. Learning and socialization can affect the microstructure and functioning of the human brain, of course, but probably not the size of its visible anatomical structures.
? Variation in the level of testosterone among different men, and in the same man in different seasons or at different times of day, correlates with libido, self-confidence, and the drive for dominance. 44 Violent criminals {348} have higher levels than nonviolent criminals; trial lawyers have higher levels than those who push paper. The relations are complicated for a number of reasons. Over a broad range of values, the concentration of testosterone in the bloodstream doesn't matter. Some traits, such as spatial abilities, peak at moderate rather than high levels. The effects of testosterone depend on the number and distribution of receptors for the molecule, not just on its concentration. And one's psychological state can affect testosterone levels as well as the other way around. But there is a causal relation, albeit a complicated one. When women preparing for a sex-change operation are given androgens, they improve on tests of mental rotation and get worse on tests of verbal fluency. The journalist Andrew Sullivan, whose medical condition had lowered his testosterone levels, describes the effects of injecting it: "The rush of a T shot is not unlike the rush of going on a first date or speaking before an audience. I feel braced. After one injection, I almost got in a public brawl for the first time in my life. There is always a lust peak -- every time it takes me unaware. "45 Though testosterone levels in men and women do not overlap, variations in level have similar kinds of effects in the two sexes. High- testosterone women smile less often and have more extramarital affairs, a stronger social presence, and even a stronger handshake.
? Women's cognitive strengths and weaknesses vary with the phase of their menstrual cycle. 46 When estrogen levels are high, women get even better at tasks on which they typically do better than men, such as verbal fluency. When the levels are low, women get better at tasks on which men typically do better, such as mental rotation. A variety of sexual motives, including their taste in men, vary with the menstrual cycle as well. 47
? Androgens have permanent effects on the developing brain, not just transient effects on the adult brain. 48 Girls with congenital adrenal hyperplasia overproduce androstenedione, the androgen hormone made famous by the baseball slugger Mark McGwire. Though their hormone levels are brought to normal soon after birth, the girls grow into tomboys, with more rough-and-tumble play, a greater interest in trucks than dolls, better spatial abilities, and, when they get older, more sexual fantasies and attractions involving other girls. Those who are treated with hormones only later in childhood show male patterns of sexuality when they become young adults, including quick arousal by pornographic images, an autonomous sex drive centered on genital stimulation, and the equivalent of wet dreams. 49
? The ultimate fantasy experiment to separate biology from socialization would be to take a baby boy, give him a sex-change operation, and have his parents raise him as a girl and other people treat him as one. If gender is socially constructed, the child should have the mind of a normal girl; if it {349} depends on prenatal hormones, the child should feel like a boy trapped in a girl's body. Remarkably,
? ? ? ? ? ? ? ? ? ? ? the experiment has been done in real life -- not out of scientific curiosity, of course, but as a result of disease and accidents. One study looked at twenty-five boys who were born without a penis (a birth defect known as cloacal exstrophy) and who were then castrated and raised as girls. All of them showed male patterns of rough-and-tumble play and had typically male attitudes and interests. More than half of them spontaneously declared they were boys, one when he was just five years old. 50
In a famous case study, an eight-month-old boy lost his penis in a botched circumcision (not by a mohel, I was relieved to learn, but by a bungling doctor). His parents consulted the famous sex researcher John Money, who had maintained that "Nature is a political strategy of those committed to maintaining the status quo of sex differences. " He advised them to let the doctors castrate the baby and build him an artificial vagina, and they raised him as a girl without telling him what had happened. 51 I learned about the case as an undergraduate in the 1970s, when it was offered as proof that babies are born neuter and acquire a gender from the way they are raised. A New York Times article from the era reported that Brenda (nee Bruce) "has been sailing contentedly through childhood as a genuine girl. "52 The facts were suppressed until 1997, when it was revealed that from a young age Brenda felt she was a boy trapped in a girl's body and gender role. 53 She ripped off frilly dresses, rejected dolls in favor of guns, preferred to play with boys, and even insisted on urinating standing up. At fourteen she was so miserable that she decided either to live her life as a male or to end it, and her father finally told her the truth. She underwent a new set of operations, assumed a male identity, and today is happily married to a woman.
Children with Turner's syndrome are genetically neuter. They have a single X chromosome, inherited from either their mother or their father, instead of the usual two X chromosomes of a girl (one from her mother, the other from her father) or the X and Y of a boy (the X from his mother, the Y from his father). Since a female body plan is the default among mammals, they look and act like girls. Geneticists have discovered that parents' bodies can molecularly imprint genes on the X chromosome so they become more or less active in the developing bodies and brains of their children. A Turner's syndrome girl who gets her X chromosome from her father may have genes that are evolutionarily optimized for girls (since a paternal X always ends up in a daughter). A Turner's girl who gets her X from her mother may have genes that are evolutionarily optimized for boys (since a maternal X, though it can end up in either sex, will act unopposed only in a son, who has no counterpart to the X genes on his puny {350} Y chromosome). And in fact Turner's girls do differ psychologically depending on which parent gave them their X. The ones with an X from their father (which is destined for a girl) were better at interpreting body language, reading emotions, recognizing faces, handling words, and getting along with other people compared to the ones with an X from their mother (which is fully active only in a boy). 54
? Contrary to popular belief, parents in contemporary America do not treat their sons and daughters very differently. 55 A recent assessment of 172 studies involving 28,000 children found that boys and
girls are given similar amounts of encouragement, warmth, nurturance, restrictiveness, discipline, and clarity of communication. The only substantial difference was that about two-thirds of the boys were discouraged from playing with dolls, especially by their fathers, out of a fear that they would become gay. (Boys who prefer girls' toys often do turn out gay, but forbidding them the toys does not change the outcome. ) Nor do differences between boys and girls depend on their observing masculine behavior in their fathers and feminine behavior in their mothers. When Hunter has two mommies, he acts just as much like a boy as if he had a mommy and a daddy.
Things are not looking good for the theory that boys and girls are born identical except for their genitalia, with all other differences coming from the way society treats them. If that were true, it would be an amazing coincidence that in every society the coin flip that assigns each sex to one set of roles would land the same way (or that one fateful flip at the dawn of the species should have been maintained without interruption across all the upheavals of the past hundred thousand years). It would be just as amazing that, time and again, society's arbitrary assignments matched the predictions that a Martian biologist would make for our species based on our anatomy and the distribution of our genes.
It would seem odd that the hormones that make us male and female in the first place also modulate the characteristically male and female mental traits, both decisively in early brain development and in smaller degrees throughout our lives. It would be all the more odd that a second genetic mechanism differentiating the sexes (genomic imprinting) also installs characteristic male and female talents. Finally, two key predictions of the social construction theory -- that boys treated as girls will grow up with girls' minds, and that differences between boys and girls can be traced to differences in how their parents treat them -- have gone down in flames.
? ? ? ? ? ? ? Of course, just because many sex differences are rooted in biology does not mean that one sex is superior, that the differences will emerge for all {351} people in all circumstances, that discrimination against a person based on sex is justified, or that people should be coerced into doing things typical of their sex. But neither are the differences without consequences.
~
By now many people are happy to say what was unsayable in polite company a few years ago: that males and females do not have interchangeable minds. Even the comic pages have commented on the shift in the debate, as we see in this dialogue between the free-associating, junkfood-loving Zippy and the cartoonist's alter ego Griffy:
? ? But among many professional women the existence of sex differences is still a source of discomfort. As one colleague said to me, "Look, I know that males and females are not identical. I see it in my kids, I see it in myself, I know about the research. I can't explain it, but when I read claims about sex differences, steam comes out of my ears". The most likely cause of her disquiet is captured in a recent editorial by Betty Friedan, the cofounder of the National Organization for Women and the author of the 1963 book The Feminine Mystique:
Though the women's movement has begun to achieve equality for women on many economic and political measures, the victory remains incomplete. To take two of the simplest and most obvious indicators: women still earn no more than 72 cents for every dollar that men earn, and we are nowhere near equality in numbers at the very top of decision making in business, government, or the professions. 56
Like Friedan, many people believe that the gender gap in wages and a "glass ceiling" that keeps women from rising to the uppermost levels of power are the two main injustices facing women in the West today. In his 1999 State of the Union address, Bill Clinton said, "We can be proud of this progress, but 75 cents on the dollar is still only three- quarters of the way there, and Americans {352} can't be satisfied until we're all the way there. " The gender gap and the glass ceiling have inspired lawsuits against companies that have too few women in the top positions, pressure on the government to regulate all salaries so men and women are paid according to the "comparable worth" of their jobs, and aggressive measures to change girls' attitudes to the professions, such as the annual Take Our Daughters to Work Day.
Scientists and engineers face the issue in the form of the "leaky pipeline. " Though women make up almost 60 percent of university students and about half of the students majoring in many fields of science, the proportion advancing to the next career stage diminishes as they go from being undergraduates to graduate students to postdoctoral fellows to junior professors to tenured professors. Women make up less than 20 percent of the workforce in science, engineering, and technology development, and only 9 percent of the workforce in engineering. 57 Readers of the flagship journals Science and Nature have seen two decades of headlines such as "Diversity: Easier Said Than Done" and "Efforts to Boost Diversity Face Persistent Problems. "58 A typical story, commenting on the many national commissions set up to investigate the problem, said, "These activities are meant to continue chipping away at a problem that, experts say, begins with negative messages in elementary school, continues through undergraduate and graduate programs that erect barriers -- financial, academic, and cultural -- to all but the best candidates, and persists into the workplace. "59 A meeting in 2001 of the presidents of nine elite American universities called for "significant changes," such as setting aside grants and fellowships for women faculty, giving them the best parking
? ? ? ? ? spaces on campus, and ensuring that the percentage of women faculty equals the percentage of women students. 60
But there is something odd in these stories about negative messages, hidden barriers, and gender prejudices. The way of science is to lay out every hypothesis that could account for a phenomenon and to eliminate all but the correct one. Scientists prize the ability to think up alternative explanations, and proponents of a hypothesis are expected to refute even the unlikely ones. Nonetheless, discussions of the leaky pipeline in science rarely even mention an alternative to the theory of barriers and bias. One of the rare exceptions was a sidebar to a 2000 story in Science, which quoted from a presentation at the National Academy of Engineering by the social scientist Patti Hausman:
The question of why more women don't choose careers in engineering has a rather obvious answer: Because they don't want to. Wherever you go, you will find females far less likely than males to see what is so fascinating about ohms, carburetors, or quarks. Reinventing the curriculum will not make me more interested in learning how my dishwasher works. 61 {353}
An eminent woman engineer in the audience immediately denounced her analysis as "pseudoscience. " But Linda Gottfredson, an expert in the literature on vocational preferences, pointed out that Hausman had the data on her side: "On average, women are more interested in dealing with people and men with things. " Vocational tests also show that boys are more interested in "realistic," "theoretical," and "investigative" pursuits, and girls more interested in "artistic" and "social" pursuits.
Hausman and Gottfredson are lonely voices, because the gender gap is almost always analyzed in the following way. Any imbalance between men and women in their occupations or earnings is direct proof of gender bias -- if not in the form of overt discrimination, then in the form of discouraging messages and hidden barriers. The possibility that men and women might differ from each other in ways that affect what jobs they hold or how much they get paid may never be mentioned in public, because it will set back the cause of equity in the workplace and harm the interests of women. It is this conviction that led Friedan and Clinton, for example, to say that we will not have attained gender equity until earnings and representation in the professions are identical for men and women. In a 1998 television interview, Gloria Steinem and the congresswoman Bella Abzug called the very idea of sex differences "poppycock" and "anti-American crazy thinking," and when Abzug was asked whether gender equality meant equal numbers in every field, she replied, "Fifty-fifty -- absolutely. "62 This analysis of the gender gap has also become the official position of universities. That the presidents of the nation's elite universities are happy to accuse their colleagues of shameful prejudice without even considering alternative explanations (whether or not they would end up accepting them) shows how deeply rooted the taboo is.
The problem with this analysis is that inequality of outcome cannot be used as proof of inequality of opportunity unless the groups being compared are identical in all of their psychological traits, which is likely to be true only if we are blank slates. But the suggestion that the gender gap may arise, even in part, from differences between the sexes can be fightin' words. Anyone bringing it up is certain to be accused of "wanting to keep women in their place" or "justifying the status quo. " This makes about as much sense as saying that a scientist who studies why women live longer than men "wants old men to die. " And far from being a ploy by self-serving men, analyses exposing the flaws of the glass-ceiling theory have largely come from women, including Hausman, Gottfredson, Judith Kleinfeld, Karen Lehrman, Cathy Young, and Camilla Benbow, the economists Jennifer Roback, Felice Schwartz, Diana Furchtgott- Roth, and Christine Stolba, the legal scholar Jennifer Braceras, and, more guardedly, the economist Claudia Goldin and the legal scholar Susan Estrich. 63
I believe these writers have given us a better understanding of the gender gap than the standard one, for a number of reasons. Their analysis is not afraid {354} of the possibility that the sexes might differ, and therefore does not force us to choose between scientific findings on human nature and the fair treatment of women. It offers a more sophisticated understanding of the causes of the gender gap, one that is consistent with our best social science. It takes a more respectful view of women and their choices. And ultimately it promises more humane and effective remedies for gender inequities in the workplace.
Before presenting the new analysis of the gender gap from equity feminists, let me reiterate three points that are not in dispute. First, discouraging women from pursuing their ambitions, and discriminating against them on the basis of their sex, are injustices that should be stopped wherever they are discovered.
Second, there is no doubt that women faced widespread discrimination in the past and continue to face it in some sectors today. This cannot be proven by showing that men earn more than women or that the sex ratio departs from fifty-fifty, but it can be proven in other ways. Experimenters can send out fake resumes or grant proposals that are identical in all ways except the sex of the applicant and see whether they are treated differently. Economists can do a regression analysis that takes measures of people's qualifications and interests and determines whether the men and the women earn different amounts, or are promoted at different rates, when their qualifications and interests are statistically held constant. The point that differences in outcome don't show discrimination unless one has equated for other relevant traits is elementary social science (not to mention common sense), and is accepted by all economists
? ? ? ? ? ? when they analyze data sets looking for evidence of wage discrimination. 64
Third, there is no question of whether women are "qualified" to be scientists, CEOs, leaders of nations, or elite professionals of any other kind. That was decisively answered years ago: some are and some aren't, just as some men are qualified and some aren't. The only question is whether the proportions of qualified men and women must be identical.
As in many other topics related to human nature, people's unwillingness to think in statistical terms has led to pointless false dichotomies. Here is how to think about gender distributions in the professions without having to choose between the extremes of "women are unqualified" and "fifty-fifty absolutely," or between "there is no discrimination" and "there is nothing but discrimination. "
In a free and unprejudiced labor market, people will be hired and paid according to the match between their traits and the demands of the job. A given job requires some mixture of cognitive talents (such as mathematical or linguistic skill), personality traits (such as risk taking or cooperation), and tolerance of lifestyle demands (rigid schedules, relocations, updating job skills). And it offers some mixture of personal rewards: people, gadgets, ideas, the {355} outdoors, pride in workmanship. The salary is influenced, among other things, by supply and demand: how many people want the job, how many can do it, and how many the employer can pay to do it. Readily filled jobs may pay less; difficult-to-fill jobs may pay more.
People vary in the traits relevant to employment. Most people can think logically, work with people, tolerate conflict or unpleasant surroundings, and so on, but not to an identical extent; everyone has a unique profile of strengths and tastes. Given all the evidence for sex differences (some biological, some cultural, some both), the statistical distributions for men and women in these strengths and tastes are unlikely to be identical. If one now matches the distribution of traits for men and for women with the distribution of the demands of the jobs in the economy, the chance that the proportion of men and of women in each profession will be identical, or that the mean salary of men and of women will be identical, is very close to zero -- even if there were no barriers or discrimination.
None of this implies that women will end up with the short end of the stick. It depends on the menu of opportunities that a given society makes available. If there are more high-paying jobs that call for typical male strengths (say, willingness to put oneself in physical danger, or an interest in machines), men may do better on average; if there are more that call for typical female strengths (say, a proficiency with language, or an interest in people), women may do better on average. In either case, members of both sexes will be found in both kinds of jobs, just in different numbers. That is why some relatively prestigious professions are dominated by women. An example is my own field, the study of language development in children, in which women outnumber men by a large margin. 65 In her book The First Sex: The Natural Talents of Women and How They Are Changing the World, the anthropologist Helen Fisher speculates that the culture of business in our knowledge-driven, globalized economy will soon favor women. Women are more articulate and cooperative, are not as obsessed with rank, and are better able to negotiate win-win outcomes. The workplaces of the new century, she predicts, will increasingly demand these talents, and women may surpass men in status and earnings.
In today's world, of course, the gap favors men. Some of the gap is caused by discrimination. Employers may underestimate the skills of women, or assume that an all-male workplace is more efficient, or worry that their male employees will resent female supervisors, or fear resistance from prejudiced customers and clients. But the evidence suggests that not all sex differences in the professions are caused by these barriers. 66 It is unlikely, for example, that among academics the mathematicians are unusually biased against women, the developmental psycholinguists are unusually biased against men, and the evolutionary psychologists are unusually free of bias.
In a few professions, differences in ability may play some role. The fact that {356} more men than women have exceptional abilities in mathematical reasoning and in mentally manipulating 3-D objects is enough to explain a departure from a fifty-fifty sex ratio among engineers, physicists, organic chemists, and professors in some branches of mathematics (though of course it does not mean that the proportion of women should be anywhere near zero).
In most professions, average differences in ability are irrelevant, but average differences in preferences may set the sexes on different paths. The most dramatic example comes from an analysis by David Lubinski and Camilla Benbow of a sample of mathematically precocious seventh-graders selected in a nationwide talent search. 67 The teenagers were born during the second wave of feminism, were encouraged by their parents to develop their talents (all were sent to summer programs in math and science), and were fully aware of their ability to achieve. But the gifted girls told the researchers that they were more interested in people, "social values," and humanitarian and altruistic goals, whereas the gifted boys said they were more interested in things, "theoretical values," and abstract intellectual inquiry. In college, the young women chose a broad range of courses in the humanities, arts, and sciences, whereas the boys were geeks who stuck to math and science. And sure enough, fewer than 1 percent of the young women pursued doctorates in math, physical sciences, or engineering, whereas 8 percent of the young men did. The women went into medicine, law, the humanities, and biology instead.
? ? ? ? ? ? This asymmetry is writ large in massive surveys of job-related values and career choices, another kind of study in which men and women actually say what they want rather than having activists speak for them. 68 On average, men's self-esteem is more highly tied to their status, salary, and wealth, and so is their attractiveness as a sexual partner and marriage partner, as revealed in studies of what people look for in the opposite sex. 69 Not surprisingly, men say they are more keen to work longer hours and to sacrifice other parts of their lives -- to live in a less attractive city, or to leave friends and family when they relocate -- in order to climb the corporate ladder or achieve notoriety in their fields. Men, on average, are also more willing to undergo physical discomfort and danger, and thus are more likely to be found in grungy but relatively lucrative jobs such as repairing factory equipment, working on oil rigs, and jack- hammering sludge from the inside of oil tanks. Women, on average, are more likely to choose administrative support jobs that offer lower pay in air-conditioned offices. Men are greater risk takers, and that is reflected in their career paths even when qualifications are held constant. Men prefer to work for corporations, women for government agencies and nonprofit organizations. Male doctors are more likely to specialize and to open up private practices; female doctors are more likely to be general practitioners on salary in hospitals and clinics. Men are more likely to be managers in factories, women more likely to be managers in human resources or corporate communications. {357} Mothers are more attached to their children, on average, than are fathers. That is true in societies all over the world and probably has been true of our lineage since the first mammals evolved some two hundred million years ago.
As Susan Estrich puts it, "Waiting for the connection between gender and parenting to be broken is waiting for Godot. " This does not mean that women in any society have ever been uninterested in work; among hunter-gatherers, women do most of the gathering and some of the hunting, especially when it involves nets rather than rocks and spears. 70 Nor does it mean that men in any society are indifferent to their children; male parental investment is a conspicuous and zoologically unusual feature of Homo sapiens. But it does mean that the biologically ubiquitous tradeoff between investing in a child and working to stay healthy (ultimately to beget or invest in other children) may be balanced at different points by males and females. Not only are women the sex who nurse, but women are more attentive to their babies' well-being and, in surveys, place a higher value on spending time with their children. 71
So even if both sexes value work and both sexes value children, the different weightings may lead women, more often than men, to make career choices that allow them to spend more time with their children -- shorter or more flexible hours, fewer relocations, skills that don't become obsolete as quickly -- in exchange for lower wages or prestige. As the economist Jennifer Roback points out, "Once we observe that people sacrifice money income for other pleasurable things we can infer next to nothing by comparing the income of one person with another's. "72 The economist Gary Becker has shown that marriage can magnify the effects of sex differences, even if they are small to begin with, because of what economists call the law of comparative advantage. In couples where the husband can earn a bit more than the wife, but the wife is a somewhat better parent than the husband, they might rationally decide they are both better off if she works less than he does. 73
To repeat: none of this means that sex discrimination has vanished, or that it is justified when it occurs. The point is only that gender gaps by themselves say nothing about discrimination unless the slates of men and women are blank, which they are not. The only way to establish discrimination is to compare their jobs or wages when choices and qualifications are equalized. And in fact a recent study of data from the National Longitudinal Survey of Youth found that childless women between the ages of twenty-seven and thirty-three earn 98 cents to men's dollar. 74 Even to people who are cynical about the motivations of American employers, this should come as no shock. In a cutthroat market, any company stupid enough to overlook qualified women or to overpay unqualified men would be driven out of business by a more meritocratic competitor.
Now, there is nothing in science or social science that would rule out policies implementing a fifty-fifty distribution of wages and jobs between the sexes, {358} if a democracy decided that this was an inherently worthy goal. What the findings do say is that such policies will come with costs as well as benefits. The obvious benefit of equality-of- outcome policies is that they might neutralize the remaining discrimination against women. But if men and women are not interchangeable, the costs have to be considered as well.
Some costs would be borne by men or by both sexes. The two most obvious are the possibility of reverse discrimination against men and of a false presumption of sexism among the men and women who make decisions about hiring and salary today. Another cost borne by both sexes is the inefficiency that could result if employment decisions were based on factors other than the best match between the demands of a job and the traits of the person. But many of the costs of equality-of-outcome policies would be borne by women. Many women scientists are opposed to hard gender preferences in science, such as designated faculty positions for women, or the policy (advocated by one activist) in which federal research grants would be awarded in exact proportion to the number of men and women who apply for them. The problem with these well-meaning policies is that they can plant seeds of doubt in people's minds about the excellence of the beneficiaries. As the astronomer Lynne Hillenbrand said, "If you're given an opportunity for the reason of being female, it doesn't do anyone any favors; it makes people question
? ? ? ? ? ? ? ? ? why you're there. "75
Certainly there are institutional barriers to the advancement of women. People are mammals, and we should think through the ethical implications of the fact that it is women who bear, nurse, and disproportionately raise children. One ought not to assume that the default human being is a man and that children are an indulgence or an accident that strikes a deviant subset. Sex differences therefore can be used to justify, rather than endanger, woman-friendly policies such as parental leave, subsidized childcare, flexible hours, and stoppages of the tenure clock or the elimination of tenure altogether (a possibility recently broached by the biologist and Princeton University president Shirley Tilghman).
Of course, there is no such thing as a free lunch, and these policies are also decisions -- perhaps justifiable ones -- to penalize men and women who are childless, have grown children, or choose to stay at home with their children. But even when it comes to weighing these tradeoffs, thinking about human nature can raise deep new questions that could ultimately improve the lot of working women. Which of the onerous job demands that deter women really contribute to economic efficiency, and which are obstacle courses in which men compete for alpha status? In reasoning about fairness in the workplace, should we consider people as isolated individuals, or should we consider them as members of families who probably will have children at some point in their lives and who probably will care for aging parents at some point in their lives? {359} If we trade off some economic efficiency for more pleasant working conditions in all jobs, might there be a net increase in happiness? I don't have answers, but the questions are well worth asking. There is one more reason that acknowledging sex differences can be more humane than denying them. It is men and women, not the male gender and the female gender, who prosper or suffer, and those men and women are endowed with brains -- perhaps not identical brains -- that give them values and an ability to make choices. Those choices should be respected. A regular feature of the lifestyle pages is the story about women who are made to feel ashamed about staying at home with their children. As they always say, "I thought feminism was supposed to be about choices. " The same should apply to women who do choose to work but also to trade off some income in order to "have a life" (and, of course, to men who make that choice). It is not obviously progressive to insist that equal numbers of men and women work eighty-hour weeks in a corporate law firm or leave their families for months at a time to dodge steel pipes on a frigid oil platform. And it is grotesque to demand (as advocates of gender parity did in the pages of Science) that more young women "be conditioned to choose engineering," as if they were rats in a Skinner box. 76
Gottfredson points out, "If you insist on using gender parity as your measure of social justice, it means you will have to keep many men and women out of the work they like best and push them into work they don't like. "77 She is echoed by Kleinfeld on the leaky pipeline in science: "We should not be sending [gifted] women the messages that they are less worthy human beings, less valuable to our civilization, lazy or low in status, if they choose to be teachers rather than mathematicians, journalists rather than physicists, lawyers rather than engineers. "78 These are not hypothetical worries: a recent survey by the National Science Foundation found that many more women than men say they majored in science, mathematics, or engineering under pressure from teachers or family members rather than to pursue their own aspirations -- and that many eventually switched out for that reason. 79 I will give the final word to Margaret Mead, who, despite being wrong in her early career about the malleability of gender, was surely right when she said, "If we are to achieve a richer culture, rich in contrasting values, we must recognize the whole gamut of human potentialities, and so weave a less arbitrary social fabric, one in which each diverse human gift will find a fitting place. "
~
Other than the gender gap, the most combustible recent issue surrounding the sexes has been the nature and causes of rape. When the biologist Randy Thornhill and the anthropologist Craig Palmer published A Natural History of Rape in 2000, they threatened a consensus that had held firm in intellectual life for a quarter of a century, and they brought down more condemnation on evolutionary psychology than any issue had in years. 80 Rape is a painful issue {360} to write about, but also an unavoidable one. Nowhere else in modern intellectual life is the denial of human nature more passionately insisted upon, and nowhere else is the alternative more deeply misunderstood. Clarifying these issues, I believe, would go a long way toward reconciling three ideals that have needlessly been put into conflict: women's rights, a biologically informed understanding of human nature, and common sense.
The horror of rape gives it a special gravity in our understanding of the psychology of men and women. There is an overriding moral imperative in the study of rape: to reduce its occurrence. Any scientist who illuminates the causes of rape deserves our admiration, like a medical researcher who illuminates the cause of a disease, because understanding an affliction is the first step toward eliminating it. And since no one acquires the truth by divine revelation, we must also respect those who explore theories that may turn out to be incorrect. Moral criticism would seem to be in order only for those who would enforce dogmas, ignore evidence, or shut down research, because they would be protecting
? ? ? ? ? ?
All this is an essential background to the discussions to come. To say that women and men do not have interchangeable minds, that people have desires other than power, and that motives belong to individual people and not just to entire genders is not to attack feminism or to compromise the interests of women, despite the misconception that gender feminism speaks in their name. All the arguments in the remainder of this chapter have been advanced most forcefully by women.
~
Why are people so afraid of the idea that the minds of men and women are not identical in every respect? Would we really be better off if everyone were like Pat, the androgynous nerd from Saturday Night Live? The fear, of course, is that different implies unequal -- that if the sexes differed in any way, then men would have to be better, or more dominant, or have all the fun.
Nothing could be farther from biological thinking. Trivers alluded to a "symmetry in human relationships," which embraced a "genetic equality of the sexes. "22 From a gene's point of view, being in the body of a male and being in the body of a female are equally good strategies, at least on average (circumstances can nudge the advantage somewhat in either direction). 23 Natural selection thus tends toward an equal investment in the two sexes: equal numbers, an equal complexity of bodies and brains, and equally effective designs for survival. Is it better to be the size of a male baboon and have six-inch canine teeth or to be the size of a female baboon and not have them? Merely to {344} ask the question is to reveal its pointlessness. A biologist would say that it's better to have the male adaptations to deal with male problems and the female adaptations to deal with female problems.
So men are not from Mars, nor are women from Venus. Men and women are from Africa, the cradle of our evolution, where they evolved together as a single species. Men and women have all the same genes except for a handful on the Y chromosome, and their brains are so similar that it takes an eagle-eyed neuroanatomist to find the small differences between them. Their average levels of general intelligence are the same, according to the best psychometric estimates,24 and they use language and think about the physical and living world in the same general way. They feel the same basic emotions, and both enjoy sex, seek intelligent and kind marriage partners, get jealous, make sacrifices for their children, compete for status and mates, and sometimes commit aggression in pursuit of their interests.
But of course the minds of men and women are not identical, and recent reviews of sex differences have converged on some reliable differences. 25 Sometimes the differences are large, with only slight overlap in the bell curves. Men have a much stronger taste for no-strings sex with multiple or anonymous partners, as we see in the almost all-male consumer base for prostitution and visual pornography. 26 Men are far more likely to compete violently, sometimes lethally, with one another over stakes great and small (as in the recent case of a surgeon and an anesthesiologist who came to blows in the operating room while a patient lay on the table waiting to have her gall bladder removed). 27 Among children, boys spend far more time practicing for violent conflict in the form of what psychologists genteelly call "rough-and-tumble play. "28 The ability to manipulate three-dimensional objects and space in the mind also shows a large difference in favor of men. 29
With some other traits the differences are small on average but can be large at the extremes. That happens for two reasons. When two bell curves partly overlap, the farther out along the tail you go, the larger the discrepancies between the groups. For example, men on average are taller than women, and the discrepancy is greater for more extreme values. At a height of five foot ten, men outnumber women by a ratio of thirty to one; at a height of six feet, men outnumber women by a ratio of two thousand to one. Also, confirming an expectation from evolutionary psychology, for many traits the bell curve for males is flatter and wider than the curve for females. That is, there are proportionally more males at the extremes. Along the left tail of the curve, one finds that boys are far more likely to be dyslexic, learning disabled, attention deficient, emotionally disturbed, and mentally retarded (at least for some types of retardation). 30 At the right tail, one finds that in a sample of talented students who score above 700 (out of 800) on the mathematics section of the {345} Scholastic Assessment Test, boys outnumber girls by thirteen to one, even though the scores of boys and girls are similar within the bulk of the curve. 31
With still other traits, the average values for the two sexes differ by smaller amounts and in different directions for different traits. 32 Though men, on average, are better at mentally rotating objects and maps, women are better at
remembering landmarks and the positions of objects. Men are better throwers; women are more dexterous. Men are better at solving mathematical word problems, women at mathematical calculation. Women are more sensitive to sounds and smells, have better depth perception, match shapes faster, and are much better at reading facial expressions and body language. Women are better spellers, retrieve words more fluently, and have a better memory for verbal material.
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Women experience basic emotions more intensely, except perhaps anger. 33 Women have more intimate social relationships, are more concerned about them, and feel more empathy toward their friends, though not toward strangers. (The common view that women are more empathic toward everyone is both evolutionarily unlikely and untrue. ) They maintain more eye contact, and smile and laugh far more often. 34 Men are more likely to compete with one another for status using violence or occupational achievement, women more likely to use derogation and other forms of verbal aggression.
Men have a higher tolerance for pain and a greater willingness to risk life and limb for status, attention, and other dubious rewards. The Darwin Awards, given annually to "the individuals who ensure the long-term survival of our species by removing themselves from the gene pool in a sublimely idiotic fashion," almost always go to men. Recent honorees include the man who squashed himself under a Coke machine after tipping it forward to get a free can, three men who competed over who could stomp the hardest on an antitank mine, and the would-be pilot who tied weather balloons to his lawn chair, shot two miles into the air, and drifted out to sea (earning just an Honorable Mention because he was rescued by helicopter).
Women are more attentive to their infants' everyday cries (though both sexes respond equally to cries of extreme distress) and are more solicitous toward their children in general. 35 Girls play more at parenting and trying on social
roles, boys more at fighting, chasing, and manipulating objects. And men and women differ in their patterns of sexual jealousy, their mate preferences, and their incentives to philander.
Many sex differences, of course, have nothing to do with biology. Hair styles and dress vary capriciously across centuries and cultures, and in recent decades participation in universities, professions, and sports has switched from mostly male to fifty-fifty or mostly female. For all we know, some of the current sex differences may be just as ephemeral. But gender feminists argue {346} that all sex differences, other than the anatomical ones, come from the expectations of parents, playmates, and society. The radical scientist Anne Fausto-Sterling wrote:
The key biological fact is that boys and girls have different genitalia, and it is this biological difference that leads adults to interact differently with different babies whom we conveniently color-code in pink or blue to make it unnecessary to go peering into their diapers for information about gender. 36
But the pink-and-blue theory is becoming less and less credible. Here are a dozen kinds of evidence that suggest that the difference between men and women is more than genitalia-deep.
? Sex differences are not an arbitrary feature of Western culture, like the decision to drive on the left or on the right. In all human cultures, men and women are seen as having different natures. All cultures divide their labor by sex, with more responsibility for childrearing by women and more control of the public and political realms by men. (The division of labor emerged even in a culture where everyone had been committed to stamping it out, the Israeli kibbutz. ) In all cultures men are more aggressive, more prone to stealing, more prone to lethal violence (including war), and more likely to woo, seduce, and trade favors for sex. And in all cultures one finds rape, as well as proscriptions against rape. 37
? Many of the psychological differences between the sexes are exactly what an evolutionary biologist who knew only their physical differences would predict. 38 Throughout the animal kingdom, when the
female has to invest more calories and risk in each offspring (in the case of mammals, through pregnancy and nursing), she also invests more in nurturing the offspring after birth, since it is more costly for a female to replace a child than for a male to replace one. The difference in investment is accompanied by a greater competition among males over opportunities to mate, since mating with many partners is more likely to multiply the number of offspring of a male than the number of offspring of a female. When the average male is larger than the average female (as is true of men and women), it bespeaks an evolutionary history of greater violent competition by males over mating opportunities. Other physical traits of men, such as later puberty, greater adult strength, and shorter lives, also indicate a history of selection for high-stakes competition.
? Many of the sex differences are found widely in other primates, indeed, throughout the mammalian class. 39 The males tend to compete more aggressively and to be more polygamous; the females tend to
invest more in {347} parenting. In many mammals a greater territorial range is accompanied by an enhanced ability to navigate using the geometry of the spatial layout (as opposed to remembering individual landmarks). More often it is the male who has the greater range, and that is true of human hunter-gatherers. Men's advantage in using mental maps and performing 3-D mental rotation may not be a coincidence. 40
? Geneticists have found that the diversity of the DNA in the mitochondria of different people (which men and women inherit from their mothers) is far greater than the diversity of the DNA in Y
? ? ? ? ? ? ? ? ? ? chromosomes (which men inherit from their fathers). This suggests that for tens of millennia men had greater variation in their reproductive success than women. Some men had many descendants and others had none (leaving us with a small number of distinct Y chromosomes), whereas a larger number of women had a more evenly distributed number of descendants (leaving us with a larger number of distinct mitochondrial genomes). These are precisely the conditions that cause sexual selection, in which males compete for opportunities to mate and females choose the best-quality males. 41
? The human body contains a mechanism that causes the brains of boys and the brains of girls to diverge during development. 42 The Y chromosome triggers the growth of testes in a male fetus, which
secrete androgens, the characteristically male hormones (including testosterone). Androgens have lasting effects on the brain during fetal development, in the months after birth, and during puberty, and they have transient effects at other times. Estrogens, the characteristically female sex hormones, also affect the brain throughout life. Receptors for the sex hormones are found in the hypothalamus, the hippocampus, and the amygdala in the limbic system of the brain, as well as in the cerebral cortex.
? The brains of men differ visibly from the brains of women in several ways. 43 Men have larger brains with more neurons (even correcting for body size), though women have a higher percentage of gray matter. (Since men and women are equally intelligent overall, the significance of these differences is unknown. ) The interstitial nuclei in the anterior hypothalamus, and a nucleus of the stria terminalis, also in the hypothalamus, are larger in men; they have been implicated in sexual behavior and aggression. Portions of the cerebral commissures, which link the left and right hemispheres, appear to be larger in women, and their brains may function in a less lopsided manner than men's. Learning and socialization can affect the microstructure and functioning of the human brain, of course, but probably not the size of its visible anatomical structures.
? Variation in the level of testosterone among different men, and in the same man in different seasons or at different times of day, correlates with libido, self-confidence, and the drive for dominance. 44 Violent criminals {348} have higher levels than nonviolent criminals; trial lawyers have higher levels than those who push paper. The relations are complicated for a number of reasons. Over a broad range of values, the concentration of testosterone in the bloodstream doesn't matter. Some traits, such as spatial abilities, peak at moderate rather than high levels. The effects of testosterone depend on the number and distribution of receptors for the molecule, not just on its concentration. And one's psychological state can affect testosterone levels as well as the other way around. But there is a causal relation, albeit a complicated one. When women preparing for a sex-change operation are given androgens, they improve on tests of mental rotation and get worse on tests of verbal fluency. The journalist Andrew Sullivan, whose medical condition had lowered his testosterone levels, describes the effects of injecting it: "The rush of a T shot is not unlike the rush of going on a first date or speaking before an audience. I feel braced. After one injection, I almost got in a public brawl for the first time in my life. There is always a lust peak -- every time it takes me unaware. "45 Though testosterone levels in men and women do not overlap, variations in level have similar kinds of effects in the two sexes. High- testosterone women smile less often and have more extramarital affairs, a stronger social presence, and even a stronger handshake.
? Women's cognitive strengths and weaknesses vary with the phase of their menstrual cycle. 46 When estrogen levels are high, women get even better at tasks on which they typically do better than men, such as verbal fluency. When the levels are low, women get better at tasks on which men typically do better, such as mental rotation. A variety of sexual motives, including their taste in men, vary with the menstrual cycle as well. 47
? Androgens have permanent effects on the developing brain, not just transient effects on the adult brain. 48 Girls with congenital adrenal hyperplasia overproduce androstenedione, the androgen hormone made famous by the baseball slugger Mark McGwire. Though their hormone levels are brought to normal soon after birth, the girls grow into tomboys, with more rough-and-tumble play, a greater interest in trucks than dolls, better spatial abilities, and, when they get older, more sexual fantasies and attractions involving other girls. Those who are treated with hormones only later in childhood show male patterns of sexuality when they become young adults, including quick arousal by pornographic images, an autonomous sex drive centered on genital stimulation, and the equivalent of wet dreams. 49
? The ultimate fantasy experiment to separate biology from socialization would be to take a baby boy, give him a sex-change operation, and have his parents raise him as a girl and other people treat him as one. If gender is socially constructed, the child should have the mind of a normal girl; if it {349} depends on prenatal hormones, the child should feel like a boy trapped in a girl's body. Remarkably,
? ? ? ? ? ? ? ? ? ? ? the experiment has been done in real life -- not out of scientific curiosity, of course, but as a result of disease and accidents. One study looked at twenty-five boys who were born without a penis (a birth defect known as cloacal exstrophy) and who were then castrated and raised as girls. All of them showed male patterns of rough-and-tumble play and had typically male attitudes and interests. More than half of them spontaneously declared they were boys, one when he was just five years old. 50
In a famous case study, an eight-month-old boy lost his penis in a botched circumcision (not by a mohel, I was relieved to learn, but by a bungling doctor). His parents consulted the famous sex researcher John Money, who had maintained that "Nature is a political strategy of those committed to maintaining the status quo of sex differences. " He advised them to let the doctors castrate the baby and build him an artificial vagina, and they raised him as a girl without telling him what had happened. 51 I learned about the case as an undergraduate in the 1970s, when it was offered as proof that babies are born neuter and acquire a gender from the way they are raised. A New York Times article from the era reported that Brenda (nee Bruce) "has been sailing contentedly through childhood as a genuine girl. "52 The facts were suppressed until 1997, when it was revealed that from a young age Brenda felt she was a boy trapped in a girl's body and gender role. 53 She ripped off frilly dresses, rejected dolls in favor of guns, preferred to play with boys, and even insisted on urinating standing up. At fourteen she was so miserable that she decided either to live her life as a male or to end it, and her father finally told her the truth. She underwent a new set of operations, assumed a male identity, and today is happily married to a woman.
Children with Turner's syndrome are genetically neuter. They have a single X chromosome, inherited from either their mother or their father, instead of the usual two X chromosomes of a girl (one from her mother, the other from her father) or the X and Y of a boy (the X from his mother, the Y from his father). Since a female body plan is the default among mammals, they look and act like girls. Geneticists have discovered that parents' bodies can molecularly imprint genes on the X chromosome so they become more or less active in the developing bodies and brains of their children. A Turner's syndrome girl who gets her X chromosome from her father may have genes that are evolutionarily optimized for girls (since a paternal X always ends up in a daughter). A Turner's girl who gets her X from her mother may have genes that are evolutionarily optimized for boys (since a maternal X, though it can end up in either sex, will act unopposed only in a son, who has no counterpart to the X genes on his puny {350} Y chromosome). And in fact Turner's girls do differ psychologically depending on which parent gave them their X. The ones with an X from their father (which is destined for a girl) were better at interpreting body language, reading emotions, recognizing faces, handling words, and getting along with other people compared to the ones with an X from their mother (which is fully active only in a boy). 54
? Contrary to popular belief, parents in contemporary America do not treat their sons and daughters very differently. 55 A recent assessment of 172 studies involving 28,000 children found that boys and
girls are given similar amounts of encouragement, warmth, nurturance, restrictiveness, discipline, and clarity of communication. The only substantial difference was that about two-thirds of the boys were discouraged from playing with dolls, especially by their fathers, out of a fear that they would become gay. (Boys who prefer girls' toys often do turn out gay, but forbidding them the toys does not change the outcome. ) Nor do differences between boys and girls depend on their observing masculine behavior in their fathers and feminine behavior in their mothers. When Hunter has two mommies, he acts just as much like a boy as if he had a mommy and a daddy.
Things are not looking good for the theory that boys and girls are born identical except for their genitalia, with all other differences coming from the way society treats them. If that were true, it would be an amazing coincidence that in every society the coin flip that assigns each sex to one set of roles would land the same way (or that one fateful flip at the dawn of the species should have been maintained without interruption across all the upheavals of the past hundred thousand years). It would be just as amazing that, time and again, society's arbitrary assignments matched the predictions that a Martian biologist would make for our species based on our anatomy and the distribution of our genes.
It would seem odd that the hormones that make us male and female in the first place also modulate the characteristically male and female mental traits, both decisively in early brain development and in smaller degrees throughout our lives. It would be all the more odd that a second genetic mechanism differentiating the sexes (genomic imprinting) also installs characteristic male and female talents. Finally, two key predictions of the social construction theory -- that boys treated as girls will grow up with girls' minds, and that differences between boys and girls can be traced to differences in how their parents treat them -- have gone down in flames.
? ? ? ? ? ? ? Of course, just because many sex differences are rooted in biology does not mean that one sex is superior, that the differences will emerge for all {351} people in all circumstances, that discrimination against a person based on sex is justified, or that people should be coerced into doing things typical of their sex. But neither are the differences without consequences.
~
By now many people are happy to say what was unsayable in polite company a few years ago: that males and females do not have interchangeable minds. Even the comic pages have commented on the shift in the debate, as we see in this dialogue between the free-associating, junkfood-loving Zippy and the cartoonist's alter ego Griffy:
? ? But among many professional women the existence of sex differences is still a source of discomfort. As one colleague said to me, "Look, I know that males and females are not identical. I see it in my kids, I see it in myself, I know about the research. I can't explain it, but when I read claims about sex differences, steam comes out of my ears". The most likely cause of her disquiet is captured in a recent editorial by Betty Friedan, the cofounder of the National Organization for Women and the author of the 1963 book The Feminine Mystique:
Though the women's movement has begun to achieve equality for women on many economic and political measures, the victory remains incomplete. To take two of the simplest and most obvious indicators: women still earn no more than 72 cents for every dollar that men earn, and we are nowhere near equality in numbers at the very top of decision making in business, government, or the professions. 56
Like Friedan, many people believe that the gender gap in wages and a "glass ceiling" that keeps women from rising to the uppermost levels of power are the two main injustices facing women in the West today. In his 1999 State of the Union address, Bill Clinton said, "We can be proud of this progress, but 75 cents on the dollar is still only three- quarters of the way there, and Americans {352} can't be satisfied until we're all the way there. " The gender gap and the glass ceiling have inspired lawsuits against companies that have too few women in the top positions, pressure on the government to regulate all salaries so men and women are paid according to the "comparable worth" of their jobs, and aggressive measures to change girls' attitudes to the professions, such as the annual Take Our Daughters to Work Day.
Scientists and engineers face the issue in the form of the "leaky pipeline. " Though women make up almost 60 percent of university students and about half of the students majoring in many fields of science, the proportion advancing to the next career stage diminishes as they go from being undergraduates to graduate students to postdoctoral fellows to junior professors to tenured professors. Women make up less than 20 percent of the workforce in science, engineering, and technology development, and only 9 percent of the workforce in engineering. 57 Readers of the flagship journals Science and Nature have seen two decades of headlines such as "Diversity: Easier Said Than Done" and "Efforts to Boost Diversity Face Persistent Problems. "58 A typical story, commenting on the many national commissions set up to investigate the problem, said, "These activities are meant to continue chipping away at a problem that, experts say, begins with negative messages in elementary school, continues through undergraduate and graduate programs that erect barriers -- financial, academic, and cultural -- to all but the best candidates, and persists into the workplace. "59 A meeting in 2001 of the presidents of nine elite American universities called for "significant changes," such as setting aside grants and fellowships for women faculty, giving them the best parking
? ? ? ? ? spaces on campus, and ensuring that the percentage of women faculty equals the percentage of women students. 60
But there is something odd in these stories about negative messages, hidden barriers, and gender prejudices. The way of science is to lay out every hypothesis that could account for a phenomenon and to eliminate all but the correct one. Scientists prize the ability to think up alternative explanations, and proponents of a hypothesis are expected to refute even the unlikely ones. Nonetheless, discussions of the leaky pipeline in science rarely even mention an alternative to the theory of barriers and bias. One of the rare exceptions was a sidebar to a 2000 story in Science, which quoted from a presentation at the National Academy of Engineering by the social scientist Patti Hausman:
The question of why more women don't choose careers in engineering has a rather obvious answer: Because they don't want to. Wherever you go, you will find females far less likely than males to see what is so fascinating about ohms, carburetors, or quarks. Reinventing the curriculum will not make me more interested in learning how my dishwasher works. 61 {353}
An eminent woman engineer in the audience immediately denounced her analysis as "pseudoscience. " But Linda Gottfredson, an expert in the literature on vocational preferences, pointed out that Hausman had the data on her side: "On average, women are more interested in dealing with people and men with things. " Vocational tests also show that boys are more interested in "realistic," "theoretical," and "investigative" pursuits, and girls more interested in "artistic" and "social" pursuits.
Hausman and Gottfredson are lonely voices, because the gender gap is almost always analyzed in the following way. Any imbalance between men and women in their occupations or earnings is direct proof of gender bias -- if not in the form of overt discrimination, then in the form of discouraging messages and hidden barriers. The possibility that men and women might differ from each other in ways that affect what jobs they hold or how much they get paid may never be mentioned in public, because it will set back the cause of equity in the workplace and harm the interests of women. It is this conviction that led Friedan and Clinton, for example, to say that we will not have attained gender equity until earnings and representation in the professions are identical for men and women. In a 1998 television interview, Gloria Steinem and the congresswoman Bella Abzug called the very idea of sex differences "poppycock" and "anti-American crazy thinking," and when Abzug was asked whether gender equality meant equal numbers in every field, she replied, "Fifty-fifty -- absolutely. "62 This analysis of the gender gap has also become the official position of universities. That the presidents of the nation's elite universities are happy to accuse their colleagues of shameful prejudice without even considering alternative explanations (whether or not they would end up accepting them) shows how deeply rooted the taboo is.
The problem with this analysis is that inequality of outcome cannot be used as proof of inequality of opportunity unless the groups being compared are identical in all of their psychological traits, which is likely to be true only if we are blank slates. But the suggestion that the gender gap may arise, even in part, from differences between the sexes can be fightin' words. Anyone bringing it up is certain to be accused of "wanting to keep women in their place" or "justifying the status quo. " This makes about as much sense as saying that a scientist who studies why women live longer than men "wants old men to die. " And far from being a ploy by self-serving men, analyses exposing the flaws of the glass-ceiling theory have largely come from women, including Hausman, Gottfredson, Judith Kleinfeld, Karen Lehrman, Cathy Young, and Camilla Benbow, the economists Jennifer Roback, Felice Schwartz, Diana Furchtgott- Roth, and Christine Stolba, the legal scholar Jennifer Braceras, and, more guardedly, the economist Claudia Goldin and the legal scholar Susan Estrich. 63
I believe these writers have given us a better understanding of the gender gap than the standard one, for a number of reasons. Their analysis is not afraid {354} of the possibility that the sexes might differ, and therefore does not force us to choose between scientific findings on human nature and the fair treatment of women. It offers a more sophisticated understanding of the causes of the gender gap, one that is consistent with our best social science. It takes a more respectful view of women and their choices. And ultimately it promises more humane and effective remedies for gender inequities in the workplace.
Before presenting the new analysis of the gender gap from equity feminists, let me reiterate three points that are not in dispute. First, discouraging women from pursuing their ambitions, and discriminating against them on the basis of their sex, are injustices that should be stopped wherever they are discovered.
Second, there is no doubt that women faced widespread discrimination in the past and continue to face it in some sectors today. This cannot be proven by showing that men earn more than women or that the sex ratio departs from fifty-fifty, but it can be proven in other ways. Experimenters can send out fake resumes or grant proposals that are identical in all ways except the sex of the applicant and see whether they are treated differently. Economists can do a regression analysis that takes measures of people's qualifications and interests and determines whether the men and the women earn different amounts, or are promoted at different rates, when their qualifications and interests are statistically held constant. The point that differences in outcome don't show discrimination unless one has equated for other relevant traits is elementary social science (not to mention common sense), and is accepted by all economists
? ? ? ? ? ? when they analyze data sets looking for evidence of wage discrimination. 64
Third, there is no question of whether women are "qualified" to be scientists, CEOs, leaders of nations, or elite professionals of any other kind. That was decisively answered years ago: some are and some aren't, just as some men are qualified and some aren't. The only question is whether the proportions of qualified men and women must be identical.
As in many other topics related to human nature, people's unwillingness to think in statistical terms has led to pointless false dichotomies. Here is how to think about gender distributions in the professions without having to choose between the extremes of "women are unqualified" and "fifty-fifty absolutely," or between "there is no discrimination" and "there is nothing but discrimination. "
In a free and unprejudiced labor market, people will be hired and paid according to the match between their traits and the demands of the job. A given job requires some mixture of cognitive talents (such as mathematical or linguistic skill), personality traits (such as risk taking or cooperation), and tolerance of lifestyle demands (rigid schedules, relocations, updating job skills). And it offers some mixture of personal rewards: people, gadgets, ideas, the {355} outdoors, pride in workmanship. The salary is influenced, among other things, by supply and demand: how many people want the job, how many can do it, and how many the employer can pay to do it. Readily filled jobs may pay less; difficult-to-fill jobs may pay more.
People vary in the traits relevant to employment. Most people can think logically, work with people, tolerate conflict or unpleasant surroundings, and so on, but not to an identical extent; everyone has a unique profile of strengths and tastes. Given all the evidence for sex differences (some biological, some cultural, some both), the statistical distributions for men and women in these strengths and tastes are unlikely to be identical. If one now matches the distribution of traits for men and for women with the distribution of the demands of the jobs in the economy, the chance that the proportion of men and of women in each profession will be identical, or that the mean salary of men and of women will be identical, is very close to zero -- even if there were no barriers or discrimination.
None of this implies that women will end up with the short end of the stick. It depends on the menu of opportunities that a given society makes available. If there are more high-paying jobs that call for typical male strengths (say, willingness to put oneself in physical danger, or an interest in machines), men may do better on average; if there are more that call for typical female strengths (say, a proficiency with language, or an interest in people), women may do better on average. In either case, members of both sexes will be found in both kinds of jobs, just in different numbers. That is why some relatively prestigious professions are dominated by women. An example is my own field, the study of language development in children, in which women outnumber men by a large margin. 65 In her book The First Sex: The Natural Talents of Women and How They Are Changing the World, the anthropologist Helen Fisher speculates that the culture of business in our knowledge-driven, globalized economy will soon favor women. Women are more articulate and cooperative, are not as obsessed with rank, and are better able to negotiate win-win outcomes. The workplaces of the new century, she predicts, will increasingly demand these talents, and women may surpass men in status and earnings.
In today's world, of course, the gap favors men. Some of the gap is caused by discrimination. Employers may underestimate the skills of women, or assume that an all-male workplace is more efficient, or worry that their male employees will resent female supervisors, or fear resistance from prejudiced customers and clients. But the evidence suggests that not all sex differences in the professions are caused by these barriers. 66 It is unlikely, for example, that among academics the mathematicians are unusually biased against women, the developmental psycholinguists are unusually biased against men, and the evolutionary psychologists are unusually free of bias.
In a few professions, differences in ability may play some role. The fact that {356} more men than women have exceptional abilities in mathematical reasoning and in mentally manipulating 3-D objects is enough to explain a departure from a fifty-fifty sex ratio among engineers, physicists, organic chemists, and professors in some branches of mathematics (though of course it does not mean that the proportion of women should be anywhere near zero).
In most professions, average differences in ability are irrelevant, but average differences in preferences may set the sexes on different paths. The most dramatic example comes from an analysis by David Lubinski and Camilla Benbow of a sample of mathematically precocious seventh-graders selected in a nationwide talent search. 67 The teenagers were born during the second wave of feminism, were encouraged by their parents to develop their talents (all were sent to summer programs in math and science), and were fully aware of their ability to achieve. But the gifted girls told the researchers that they were more interested in people, "social values," and humanitarian and altruistic goals, whereas the gifted boys said they were more interested in things, "theoretical values," and abstract intellectual inquiry. In college, the young women chose a broad range of courses in the humanities, arts, and sciences, whereas the boys were geeks who stuck to math and science. And sure enough, fewer than 1 percent of the young women pursued doctorates in math, physical sciences, or engineering, whereas 8 percent of the young men did. The women went into medicine, law, the humanities, and biology instead.
? ? ? ? ? ? This asymmetry is writ large in massive surveys of job-related values and career choices, another kind of study in which men and women actually say what they want rather than having activists speak for them. 68 On average, men's self-esteem is more highly tied to their status, salary, and wealth, and so is their attractiveness as a sexual partner and marriage partner, as revealed in studies of what people look for in the opposite sex. 69 Not surprisingly, men say they are more keen to work longer hours and to sacrifice other parts of their lives -- to live in a less attractive city, or to leave friends and family when they relocate -- in order to climb the corporate ladder or achieve notoriety in their fields. Men, on average, are also more willing to undergo physical discomfort and danger, and thus are more likely to be found in grungy but relatively lucrative jobs such as repairing factory equipment, working on oil rigs, and jack- hammering sludge from the inside of oil tanks. Women, on average, are more likely to choose administrative support jobs that offer lower pay in air-conditioned offices. Men are greater risk takers, and that is reflected in their career paths even when qualifications are held constant. Men prefer to work for corporations, women for government agencies and nonprofit organizations. Male doctors are more likely to specialize and to open up private practices; female doctors are more likely to be general practitioners on salary in hospitals and clinics. Men are more likely to be managers in factories, women more likely to be managers in human resources or corporate communications. {357} Mothers are more attached to their children, on average, than are fathers. That is true in societies all over the world and probably has been true of our lineage since the first mammals evolved some two hundred million years ago.
As Susan Estrich puts it, "Waiting for the connection between gender and parenting to be broken is waiting for Godot. " This does not mean that women in any society have ever been uninterested in work; among hunter-gatherers, women do most of the gathering and some of the hunting, especially when it involves nets rather than rocks and spears. 70 Nor does it mean that men in any society are indifferent to their children; male parental investment is a conspicuous and zoologically unusual feature of Homo sapiens. But it does mean that the biologically ubiquitous tradeoff between investing in a child and working to stay healthy (ultimately to beget or invest in other children) may be balanced at different points by males and females. Not only are women the sex who nurse, but women are more attentive to their babies' well-being and, in surveys, place a higher value on spending time with their children. 71
So even if both sexes value work and both sexes value children, the different weightings may lead women, more often than men, to make career choices that allow them to spend more time with their children -- shorter or more flexible hours, fewer relocations, skills that don't become obsolete as quickly -- in exchange for lower wages or prestige. As the economist Jennifer Roback points out, "Once we observe that people sacrifice money income for other pleasurable things we can infer next to nothing by comparing the income of one person with another's. "72 The economist Gary Becker has shown that marriage can magnify the effects of sex differences, even if they are small to begin with, because of what economists call the law of comparative advantage. In couples where the husband can earn a bit more than the wife, but the wife is a somewhat better parent than the husband, they might rationally decide they are both better off if she works less than he does. 73
To repeat: none of this means that sex discrimination has vanished, or that it is justified when it occurs. The point is only that gender gaps by themselves say nothing about discrimination unless the slates of men and women are blank, which they are not. The only way to establish discrimination is to compare their jobs or wages when choices and qualifications are equalized. And in fact a recent study of data from the National Longitudinal Survey of Youth found that childless women between the ages of twenty-seven and thirty-three earn 98 cents to men's dollar. 74 Even to people who are cynical about the motivations of American employers, this should come as no shock. In a cutthroat market, any company stupid enough to overlook qualified women or to overpay unqualified men would be driven out of business by a more meritocratic competitor.
Now, there is nothing in science or social science that would rule out policies implementing a fifty-fifty distribution of wages and jobs between the sexes, {358} if a democracy decided that this was an inherently worthy goal. What the findings do say is that such policies will come with costs as well as benefits. The obvious benefit of equality-of- outcome policies is that they might neutralize the remaining discrimination against women. But if men and women are not interchangeable, the costs have to be considered as well.
Some costs would be borne by men or by both sexes. The two most obvious are the possibility of reverse discrimination against men and of a false presumption of sexism among the men and women who make decisions about hiring and salary today. Another cost borne by both sexes is the inefficiency that could result if employment decisions were based on factors other than the best match between the demands of a job and the traits of the person. But many of the costs of equality-of-outcome policies would be borne by women. Many women scientists are opposed to hard gender preferences in science, such as designated faculty positions for women, or the policy (advocated by one activist) in which federal research grants would be awarded in exact proportion to the number of men and women who apply for them. The problem with these well-meaning policies is that they can plant seeds of doubt in people's minds about the excellence of the beneficiaries. As the astronomer Lynne Hillenbrand said, "If you're given an opportunity for the reason of being female, it doesn't do anyone any favors; it makes people question
? ? ? ? ? ? ? ? ? why you're there. "75
Certainly there are institutional barriers to the advancement of women. People are mammals, and we should think through the ethical implications of the fact that it is women who bear, nurse, and disproportionately raise children. One ought not to assume that the default human being is a man and that children are an indulgence or an accident that strikes a deviant subset. Sex differences therefore can be used to justify, rather than endanger, woman-friendly policies such as parental leave, subsidized childcare, flexible hours, and stoppages of the tenure clock or the elimination of tenure altogether (a possibility recently broached by the biologist and Princeton University president Shirley Tilghman).
Of course, there is no such thing as a free lunch, and these policies are also decisions -- perhaps justifiable ones -- to penalize men and women who are childless, have grown children, or choose to stay at home with their children. But even when it comes to weighing these tradeoffs, thinking about human nature can raise deep new questions that could ultimately improve the lot of working women. Which of the onerous job demands that deter women really contribute to economic efficiency, and which are obstacle courses in which men compete for alpha status? In reasoning about fairness in the workplace, should we consider people as isolated individuals, or should we consider them as members of families who probably will have children at some point in their lives and who probably will care for aging parents at some point in their lives? {359} If we trade off some economic efficiency for more pleasant working conditions in all jobs, might there be a net increase in happiness? I don't have answers, but the questions are well worth asking. There is one more reason that acknowledging sex differences can be more humane than denying them. It is men and women, not the male gender and the female gender, who prosper or suffer, and those men and women are endowed with brains -- perhaps not identical brains -- that give them values and an ability to make choices. Those choices should be respected. A regular feature of the lifestyle pages is the story about women who are made to feel ashamed about staying at home with their children. As they always say, "I thought feminism was supposed to be about choices. " The same should apply to women who do choose to work but also to trade off some income in order to "have a life" (and, of course, to men who make that choice). It is not obviously progressive to insist that equal numbers of men and women work eighty-hour weeks in a corporate law firm or leave their families for months at a time to dodge steel pipes on a frigid oil platform. And it is grotesque to demand (as advocates of gender parity did in the pages of Science) that more young women "be conditioned to choose engineering," as if they were rats in a Skinner box. 76
Gottfredson points out, "If you insist on using gender parity as your measure of social justice, it means you will have to keep many men and women out of the work they like best and push them into work they don't like. "77 She is echoed by Kleinfeld on the leaky pipeline in science: "We should not be sending [gifted] women the messages that they are less worthy human beings, less valuable to our civilization, lazy or low in status, if they choose to be teachers rather than mathematicians, journalists rather than physicists, lawyers rather than engineers. "78 These are not hypothetical worries: a recent survey by the National Science Foundation found that many more women than men say they majored in science, mathematics, or engineering under pressure from teachers or family members rather than to pursue their own aspirations -- and that many eventually switched out for that reason. 79 I will give the final word to Margaret Mead, who, despite being wrong in her early career about the malleability of gender, was surely right when she said, "If we are to achieve a richer culture, rich in contrasting values, we must recognize the whole gamut of human potentialities, and so weave a less arbitrary social fabric, one in which each diverse human gift will find a fitting place. "
~
Other than the gender gap, the most combustible recent issue surrounding the sexes has been the nature and causes of rape. When the biologist Randy Thornhill and the anthropologist Craig Palmer published A Natural History of Rape in 2000, they threatened a consensus that had held firm in intellectual life for a quarter of a century, and they brought down more condemnation on evolutionary psychology than any issue had in years. 80 Rape is a painful issue {360} to write about, but also an unavoidable one. Nowhere else in modern intellectual life is the denial of human nature more passionately insisted upon, and nowhere else is the alternative more deeply misunderstood. Clarifying these issues, I believe, would go a long way toward reconciling three ideals that have needlessly been put into conflict: women's rights, a biologically informed understanding of human nature, and common sense.
The horror of rape gives it a special gravity in our understanding of the psychology of men and women. There is an overriding moral imperative in the study of rape: to reduce its occurrence. Any scientist who illuminates the causes of rape deserves our admiration, like a medical researcher who illuminates the cause of a disease, because understanding an affliction is the first step toward eliminating it. And since no one acquires the truth by divine revelation, we must also respect those who explore theories that may turn out to be incorrect. Moral criticism would seem to be in order only for those who would enforce dogmas, ignore evidence, or shut down research, because they would be protecting
? ? ? ? ? ?
