American Scientist

Sex: A Natural History. Joann Ellison Rodgers. xxviii + 515 pp. W. H. Freeman, 2001. $32.50.

The Science of Romance: Secrets of the Sexual Brain. Nigel Barber. 293 pp. Prometheus Books, 2002. $26.

Perhaps one of the real joys of sex is to understand it. If that's your goal, you'll want to read Sex: A Natural History and The Science of Romance. Both books are excellent: Accurate, entertaining and thought-provoking, they are also sturdy, important additions to the body of literature explaining why sex evolved and what evolutionary forces underlie current forms of sexual expression. As preparation for writing Sex, journalist Joann Ellison Rodgers spent five years immersing herself in the literature of evolutionary psychology. Nigel Barber, the author of The Science of Romance, is an evolutionary psychologist.

The relatively new intellectual framework of sociobiology, which underpins both books, represents an exceedingly important paradigm shift. Unfortunately, this discipline still has a long way to go before achieving full acceptance. One impediment to its progress has been the influence of Sigmund Freud.

Rodgers mentions Freud in order to dismiss him, writing of the "damage done to human sexual inquiry by the Freudian century." I think she is correct in being so harsh, but it is worth reminding ourselves how difficult it has been—and still is—to apply evolutionary insights to sexual behavior. Charles Darwin published The Descent of Man, and Selection in Relation to Sex in 1871, when Freud was 15. As a mature thinker Freud certainly must have read it. If he had been born 50 years later, perhaps he would have become a pioneer evolutionary psychologist. His first publication was on the evolution of the spinal cord, and he wrote several other papers on the evolution of the nervous system. But instead of building on these anatomical contributions to Darwinian evolution by adding insights from animal behavior, Freud created a house of cards literally built on dreams.

Did the sexually constrained world of Vienna in the 1890s make it impossible to accept that studies of animal behavior could contribute to an understanding of our own sexuality? Or was it that the modern contributions of entomologists, ornithologists and primatologists were unavailable to Freud? Whatever the reason, it took a long time to apply evolutionary findings to sexuality.

Fortunately, the insights that evolutionary psychology has produced are finally reaching a wide audience. In Freud's day, people spoke at cocktail parties of men with big egos; today, the term alpha male has entered everyday vocabulary. This change is more than a mere alteration in fashion: The term ego is only a label, whereas alpha male carries with it an explanatory element. Male competition exists because that is the way evolution works, just as hydrogen and oxygen join to make water because that is the way atomic nuclei and electron orbitals work.

In The Descent of Man, Darwin pointed out that reproductive competition results in males and females having distinct sexual agendas. The differences are especially marked in mammals, because mammalian females invest much more in reproduction than do males. Males compete for access to females; females compete for access to resources. Much of what Rodgers and Barber are writing about grows out of this simple but important principle.

I suspect that if Rodgers (a woman) and Barber (a man) ever met, they would agree that their approaches to the topic were influenced by gender. The arguments they put forward do not conflict, but their emphases often diverge, perhaps because men and women do indeed see the world differently. Both books ask—and to a large extent answer—these questions: Why is sex so compelling yet paradoxical, wonderful yet painful, intimate yet shameful? Why do we seek it so avidly, yet make so many mistakes?

Sex: A Natural History is 500 pages long and packed with details; unfortunately, no references are provided, only a bibliography of the many studies consulted. Rodgers stresses the psychological aspects of sex, pointing out that the brain is far more important than reproductive organs for how sex roles are played out. Her concluding chapter is particularly valuable, emphasizing the creative compromises characteristic of heterosexual relationships and pointing out that the sexes cooperate more than they battle.

The Science of Romance covers the same ground as Sex in half the pages and uses some well-chosen photographs; detailed references are provided for each chapter. Barber takes a problem-solving approach. He is especially interesting when exploring how the ratio of eligible men and women in the marriage market helps determine divorce rates, and when explaining patterns of childbearing in African-American communities. He delves more deeply into the aggressive side of sex than does Rodgers.

I teach an undergraduate course on human sexuality. The glossy university textbooks I've seen on the subject are nearly all politically correct works of social constructionism, insisting that males and females are guided by their cultures into their respective roles and behaviors. In some of them, Darwin doesn't even appear in the index. I'm afraid that academic sociologists and anthropologists have been slower to accept evolutionary psychology than have nonacademicians who read and watch public television. In a recent review of another book on evolutionary psychology, one social scientist wrote that she and her colleagues "will go about their business with a happy indifference" to this new perspective.

Such intellectual inertia perhaps explains why it has taken a hundred years for Freud's misinterpretations to begin to disappear. Will it take another century for the oversimplification of social constructionism to be replaced by a richer, more challenging synthesis that combines inherited predispositions and cultural influences? Not if books as good as these two continue to be published.—Malcolm Potts, School of Public Health, University of California, Berkeley