Suppose my utopian vision, as described in the last chapter, came to pass. Would all gender differences disappear? Would we award jobs, status, income, and social roles based only on individual differences in physique, intellect, and inclination? Perhaps. But some would argue that no matter how widely we opened the door, ineluctable differences between groups would remain. Scientists, such naysayers would argue, have proven that in addition to our genitalia, key anatomical differences between the male and female brain make gender an important marker of ability. To drive home their point, they might cite well-publicized claims that, compared to men’s, the corpus callosum—the bundle of nerve fibers connecting the left and right brain hemispheres—in women’s brains is larger or more bulbous. And that, they would exclaim, will limit forever the degree to which most women can become highly skilled mathematicians, engineers, and scientists. But not everybody believes in this difference in brain anatomy.
External anatomy seems simple. Does the baby’s hand have five or six fingers? Just count them. Do boys have penises and girls vaginas (intersexuals notwithstanding)? Just look. Who could disagree about body parts? Scientists use the rhetoric of visibility to talk about gender differences in the brain, but moving from easily examined external structures to the anatomy of the interior is tricky. Relationships among gender, brain function, and anatomy are both hard to interpret and difficult to see, so scientists go to great lengths to convince each other and the general public that gender differences in brain anatomy are both visible and meaningful.1 Some such claims provoke battles that can last for hundreds of years.2 In coming to understand how and why these battles can last so long, I continue to insist that scientists do not simply read nature to find truths to apply in the social world. Instead, they use truths
taken from our social relationships to structure, read, and interpret the natural.3
Medical ‘‘solutions’’ to intersexuality developed as scientific innovations, ranging from new methods of classification to new skills in microscopy, interacted with the preconception that there are only two genders. Scientific unanimity reigned in part because the social beliefs about male and female were not in dispute. But when the social arena forms a battleground, scientists have a hard time developing a consensus. In this chapter, I show how, as they move from difference on the body’s surface to interior differences, scientists use their tools to debate about masculinity and femininity. For what professions are those with ‘‘masculine’’ or ‘‘feminine’’ brains most suited? Should special efforts be made to encourage women to become engineers? Is it ‘‘natural’’ for boys to have trouble learning to read? Are gay men more suited to feminine professions such as hairdressing or flower arranging because of a more feminine corpus callosum? These interlocking social questions sustain the debate about the anatomy of the corpus callosum.4
The winter of 1992 was a hard one. There was nothing to do but sit around and contemplate our collective corpus callosums. Or so it seemed; what else would explain the sudden spate of news articles about this large bundle of nerve fibers connecting the left and right brain hemispheres? Newsweek and Time magazines started the trend by running feature stories about gender differences and the brain.5 Women, a Time illustration informed its readers, often had wider corpus callosums than men. This difference, suggested a caption to one of the glossy illustrations, could ‘‘possibly [provide] the basis for woman’s intuition.’’ The text of the article concedes that not all neurobiologists believe in this alleged brain difference. Meme Black, writing for Elle, was less cautious: that women have larger corpus callosums, she wrote, could explain why ‘‘girls are less apt than boys to gravitate toward fields like physics and engineering.’’6
Others agreed. A Boston Globe article about gender difference and the corpus callosum quoted Dr. Edith Kaplan, a psychiatrist and neurologist: ‘‘throughout life men’s and women’s brains are anatomically different, with women having a thicker corpus callosum. . . . Because of these interconnections,’’ she suggests, women have stronger verbal skills and men stronger visuo-spatial ones.7 Not to be outdone, The New York Times science editor Nicholas Wade wrote that definitive research that revealed callosal sex differences discredited ‘‘some feminist ideologues» who ‘‘assert that all minds are created equal and women would be just as good at math if they weren’t discouraged in school.’’ 8 (Imagine!)
Nor did the intrigue stop with questions about whether women’s brains
made them unsuitable for science careers. Rather, the media seemed prepared to believe that all physiological and social differences could ultimately be traced to differences in the form of one part of the brain. Follow the logic of a 1995 Newsweek cover story entitled ‘‘Why Men and Women Think Differently,’’ suggesting that brain differences in the corpus callosum might explain why women think holistically (assuming they do), while men’s right brains don’t know what their left is doing (if that is, indeed, the case). ‘‘Women have better intuition,’’ the author stated, ‘‘perhaps because they are in touch with the left brain’s rationality and the right’s emotions simultaneously.’’9 To support this theory the article cited studies that found CAH girls to be more male-like than other girls in both play patterns and cognitive strengths, and suggested—in a stunning piece of circular reasoning—that such studies might indicate that sex hormones are responsible for differences in CC size.10
As if this sort of argument were not far-fetched enough, some pushed the CC determinism even further. In 1992, for instance, the psychologist Sandra Witelson mixed a different seasoning into the stew, publishing an article in which she argued that just as men and women differ in cognitive abilities and CC structure, so too did gay and straight men. (As usual, lesbians were nowhere to be found.) ‘‘It is as if, in some cognitive respects, [gay men] are neurologically a third sex,’’ she wrote, adding that the brain differences may eventually help account for ‘‘the apparently greater prevalence and ability of homosexual men compared to heterosexual men in some professions.’’11 She didn’t elaborate on just which professions she meant, but by arguing that the form of the corpus callosum helps determine handedness, gender identity, cognitive patterns, and sexual preference, she effectively suggested that this one area of the brain plays a role in regulating almost every aspect of human behavior.12
These newspaper and magazine stories show us the corpus callosum hard at work, its sleeves rolled up, sweat pouring down its face, as it strives to provide researchers with a single anatomical control center, a physical origin for an array of physiological and social variations. Why does the CC have to work so hard? Why don’t the facts just speak for themselves? In the late 1800s anatomists, who had previously always drawn male skeletons, suddenly developed an interest in female bone structure. Because the skeleton was seen to be the fundamental structure—the material essence of the body—finding sex differences would make clear that sexual identity penetrated ‘‘every muscle, vein and organ attached to and molded by the skeleton.’’13 A controversy arose. One scientist—a woman—drew females with skulls proportionately smaller than those of males, while another—a male—painted women whose skulls were larger relative to the rest of their bodies than were those of males.
At first everyone favored the former drawings, but—after much back and forth—scientists conceded the accuracy of the latter. Nevertheless, scientists clung to the fact that women’s brains were smaller in absolute size, thus proving that women were less intelligent.14 Today we turn to the brain rather than the skeleton to locate the most fundamental sources of sexual difference.15 But, despite the many recent insights of brain research, this organ remains a vast unknown, a perfect medium on which to project, even unwittingly, assumptions about gender.
The contemporary CC debate began in 1982 when the prestigious journal Science published a brief article by two physical anthropologists. The paper received instant notoriety when the talk-show host Phil Donahue inaccurately credited the authors with describing ‘‘an extra bundle of neurons that was missing in male brains.’’16 The Science article reported that certain regions of the corpus callosum were larger in females than in males. Although admittedly preliminary (the study used nine males and five females), the authors boldly related their results to ‘‘possible gender differences in the degree of lateralization for visuospatial functions.’’17Here’s the lay translation: some psychologists (but not all18) believe that men and women use their brains differently. Men, supposedly, make almost exclusive use of the left hemisphere when processing visuo-spatial information, while women allegedly use both hemispheres. In psycho-jargon, men are more lateralized for visuo-spatial tasks. Layered on top of this claim is another (also disputed), that greater lateralization implies greater skill capacity. Men often perform better on standardized spatial tasks, and many believe that this also explains their better performance in mathematics and science. If one buys this story and if one believes that the posited functional differences are inborn (resulting, for example, from anatomical differences, perhaps induced by hormones during fetal development), then one can argue that it makes no sense to develop a social policy calling for equal representation of men and women in fields such as engineering and physics. You can’t, after all, squeeze blood out of a stone.
The psychologist Julian Stanley, who heads a national program for mathematically talented youth, recently reported that male twelfth graders got higher scores on Advanced Placement tests in physics. He believes the test scores imply that ‘‘few females will be found to reason as well mechanically as most males do. This could be a serious handicap in fields such as electrical engineering and mechanics. . . . Such discrepancies would. . .make it inadvisable to assert that there should be as many female as male electrical engineers.’’ ‘‘It doesn’t make sense,’’ he continued, ‘‘to suppose that parity is a feasible goal until we find ways to increase such abilities among females.’’19 Meanwhile, Stanley’s colleague, Dr. Camilla Benbow, suggests with very little evidence20 that sex differences in mathematics may emanate, at least in part, from inborn differences in brain lateralization.21
We see the corpus callosum employed here as part of what Donna Haraway calls ‘‘the technoscientific body.’’ It is a node from which emanate ‘‘sticky threads’’ that traverse our gendered world, trapping bits and pieces like newly hung flypaper.22 Callosal narratives become colossal, linking the underrepresentation of women in science with hormones, patterns of cognition, how best to educate boys and girls,23 homosexuality, left versus righthandedness, and women’s intuition.24 The sticky threads do not restrict themselves to gender narratives, but glue themselves as well to stories about race and nationality. In the nineteenth and early twentieth centuries the CC itself was racially implicated. In the late twentieth century, styles of thinking (thought by many to be indirectly mediated by the CC25) are often racialized. Instead of learning that ‘‘Negroes’’ have smaller CC’s than Caucasians,26 we now hear that Native Americans or Asians (of every stripe) think more holistically than do Europeans. In discussions of the corpus callosum and its role in connecting left and right brain hemispheres, the slippery dualisms that Val Plumwood warned us against (see chapter i) abound (table 5.1). The CC does not easily bear such weight, and therein lies the heart of this chapter. How have scientists turned the corpus callosum into an object of knowledge? Given this techno-scientific object’s recalcitrance, what are the scientific weapons deployed in the battle to make the corpus callosum do gender’s bidding?