BOOK REVIEW / SCIENCE : Nature Versus Nurture in Sex Differences : EVE’S RIB; Searching For the Biological Roots of Sex Differences <i> by Robert Pool</i> ; Crown Publishers; $22, 320 pages
If you’ve never looked closely at a pack of hyenas, you’ll surely want to after reading the introduction to “Eve’s Rib.” Hyenas, Robert Pool tells us, differ from other mammals because both sexes sport either male or male-look-alike genitalia, and specially for them nature has evolved a mind-boggling solution to the usually simple matter of copulation.
Why does Pool begin his first book, an examination of the biological roots of sex in people, with an account of a non-human animal? So he can draw an analogy, of course. In hyenas, as in people, it’s a question of hormones. A pregnant hyena’s blood is so rich in the male hormone testosterone that the resulting litter boasts the most aggressive infants--female and male--in all mammaldom.
With humans, as a rule, only males get drenched in testosterone; but in special cases, which Pool describes in elegant detail, little girls with chromosomal or developmental anomalies receive an extra dollop of uterine testosterone. These “tomboys” are super-aggressive, scorn dolls in favor of trucks, and a favored few excel in mathematical problems that demand spatial ability.
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In this book, Pool enters the nature-nurture debate as it applies to sexual differences. He tries to give equal attention to both sides, and insists that the positions are complementary rather than opposite.
In the end, however, he concludes that, while socialization is very important, “the question here was what type of role nature plays in creating differences between males and females. The answer is: a major one.”
He supports this conclusion with descriptions of psychological, endocrinological and neurobiological research, beginning with the study done at Johns Hopkins University in the 1970s in which highly gifted junior high school boys outperformed similarly gifted girls in a special mathematics program.
He interviews a complicated network of researchers whose studies range from the Hopkins exploration of women and math to an examination of how men and women recover differently from stroke in terms of the organization of the male and female brain.
Citing evidence that girls and boys are different from the first days of life, and that groups of little boys behave differently from groups of little girls (as any parent will testify), we are convinced, if we had many doubts to begin with, that boys are different from girls.
How much difference there is, and what this difference implies, is another matter. If there are more male math geniuses than female math geniuses, what has that to do with most men and women who are not geniuses? What about the skills of people in the middle of the curve?
Pool has interesting information about the rest of us. Studies of infants, for instance, show that from the very first hours of life, the sexes differ in making eye contact. Is there a connection between early sociability, the ways girls and boys meet the world, and the apparently different ways that our brains are organized? There is no answer . . . yet.
Nor can anyone explain the origins of the differences we can expose. They are lost in our evolutionary past when, Pool suggests, it may have been advantageous for our ancestral hunter-gatherer menfolk to be proto-engineers and the womenfolk to be proto-homemakers. But whatever the reasons, we are struck with these differences today, even as we work to level the playing field in a very different world.
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Pool is struck by the rigor of the scientists he interviews, and by the fact that they are overwhelmingly women who were educated in the ‘70s when the idea of nurture was more popular on campuses than the idea of nature . Whatever their politics then and now, he describes them as a mixed batch--married, divorced and single, social scientists, biologists and doctors.
Pool’s interest in their private lives is part of the pervasive subtext to what is often a remarkable book. This subtext is spelled out in his dedication: “To the love of my life, my sage and my wife, Amy.”
Unfortunately, his devotion has leaked into his narrative, and Amy’s talents, whims and personal conflicts about her approaching maternity become a secondary theme. While not exactly his co-author, Amy is omnipresent.
It is too bad he didn’t pursue the solution reached by Camilla Benbow (one of the Hopkins researchers) who has seven children and chairs the psychology department at Iowa State University, or the decision of Sandra Witelson at McMaster University to stop at one for fear that another child would have jeopardized her chance of getting tenure. By universalizing his marriage, Pool has reduced the impact of this rich material to an apologetic shrug.
