eggs, because men don’t have to invest much of worth in reproduction while women invest not only their ova but their bodies, as they take on the tolls and risks of pregnancy and childbirth, because women then invest further in breast-feeding (the investment being in time, in extra calories required, and in the postponed ability to conceive another child)—because of this economy of input, far more pressingly relevant to our prehistoric ancestors, to our ever-endangered forebears, than to the humans of today, males have been programmed, since way back when, to ensure and expand their genetic legacy by spreading their cheap seed, while females have been scripted to maximize their investment by being choosy, by securing a male likely to have good genes and be a good long-term provider to her and her offspring.
This all fits neatly with the evidence from Zambia, Yugoslavia, Palestinian towns, Australia, America, Japan. And the theory’s stark economic terms have a solid, incontrovertible sound. Our erotic beings, the differences in desire we observe between the genders, are the inevitable manifestations of evolutionary forces from eons ago. Parental investment theory gratifies one of our urgent longings: for simple answers about how we’ve come to be the way we are.
But the theory’s foundation is precarious at best. Does the fact that women are expected to be the more demure gender in Lusaka and New York, in Kabul and Kandahar and Karachi and Kansas City, prove anything about our erotic hardwiring? Might the shared value placed on female modesty speak less to absolutes of biology than to the world’s span of male-dominated cultures and historic suspicion and fear of female sexuality?
And then, what of Chivers’s plethysmograph, which made a myth out of appearances? What of the drives that lie concealed beneath the surface, that crouch within the strictures? The sexual insights of evolutionary psychology can sometimes seem nothing but a conservative fable, conservative perhaps inadvertently but nevertheless preservationist in spirit, protective of a sexual status quo. Women, the fable teaches, are naturally the more restrained sex; this is the inborn norm; this is normal. And the normal always wields a self-confirming and self-perpetuating power. Because few people like to defy it, to stray from it.
One recent pop psychology mega-seller, The Female Brain, opens with lessons grounded in parental investment theory and serves as an emblem of the ways evolutionary psychology has spread its sexual vision throughout the culture. “The girl brain” is a “machine built for connection,” for attachment. “That’s what it drives a female to do from birth. This is the result of millennia of genetic and evolutionary hardwiring.” The boy brain-machine is very different; it is built for “frenzies” of lust.
The book, like loads of others in the pop psychology genre, pretends to back its evolutionary theory with something concrete, with the technology known as functional magnetic resonance imaging, fMRI—with pictures of the brain at work. But the technology is nowhere near being up to the task. To spend time in fMRI laboratories, to stare alongside neuroscientists while fMRI data is sent from subjects’ brains to lab computers, to listen as those neuroscientists strain to read and parse the pictures of brain regions forming on their monitors, as I have, and to ask bluntly about the state of our seemingly miraculous equipment, its capabilities much hyped by the media, is to understand that our technology is not at all precise enough to subdivide and apprehend the miniscule sub-regions and interlaced brain systems that enact our complex emotions, among them the wish to have sex. When, on the news or in a magazine, we hear or read something like, “The hippocampus lit up as subjects looked at photographs of . . .” we are learning something about as specific as a TV traffic reporter scanning from a helicopter and being able to say only, “The heavy traffic is somewhere in northern New Jersey.” As scientists told me again and again, brain imaging just isn’t a way to determine much of anything definitive about female versus male emotional neurology, not yet. And such technology may never be the right way to study inborn differences between the genders, because experience—use and disuse, positive and negative reinforcement—is forever altering neurological systems, strengthening some and weakening others.
Proclamations like the ones in The Female Brain—about connection versus frenzies, or about how a woman, to have satisfying sex, must be “comfortable, warm, and cozy” and, “most important,” has “to trust who she is with”—are in striking parallel with the teachings of fundamentalist Christianity. The secular version is less extreme, but the messages are similar. As a pair of health education programs, designed by evangelicals and used in thousands of public schools within the past decade, instructed in their charts, the “five major needs of women” in marriage are topped by “affection” and “conversation.” Sex is nowhere in the five. Across the page, the male list is led by “sexual fulfillment.” In another graphic titled “Guys and Girls are Different,” girls have an equals sign between “sex” and “personal relationship.” Guys have the sign crossed out.
So, with scientific or God-given confidence, girls and women are told how they should feel.
CHAPTER FOUR
Monkeys and Rats
Her unruly red-blond hair tufting atop her head, Deidrah sat beside Oppenheimer. She lipped his ear. She mouthed his chest. She kissed his belly over and over, lips lingering with each kiss. After a while, he pulled himself up and strolled away from her attentions, glancing back over his shoulder to see if she was following. She was.
Deidrah, who was probably the most reserved female monkey in the compound, started in again on his white-haired torso as they sat together on a concrete curb. The habitat, a one-hundred-and-twenty-foot square, was filled with ladders and ropes and assorted apparatus donated by a local fire department and by McDonald’s; an environment of trees and vines would have been too expensive to create and maintain. A trio of monkey children sprinted toward a tube, disappeared inside it, burst from the other end, and raced around for another run-through, berserk with joy.
From a platform on a steel tower, I watched with Kim Wallen, his beard silver, his eyes alight. A psychologist and neuroendocrinologist, he spent much of his time here at Yerkes, an Emory University research center outside Atlanta that was home to two thousand primates. We gazed down at the habitat’s seventy-five rhesus, a monkey species that had been sent into orbit in spaceships, in the fifties and sixties, as stand-ins for humans to see if we could survive trips to the moon. Wallen had lived on a farm as a child when his father, a psychologist, decided to try out a utopian dream of cooperative goat-rearing. Wallen’s observation of animal sexuality had begun then. He’d been watching monkeys now for decades.
“Females were passive. That was the theory in the middle seventies. That was the wisdom,” he remembered the start of his career. Deidrah’s face, always a bit redder than most, was luminous this morning, lit scarlet with lust as she lifted it from Oppenheimer’s chest. “The prevailing model was that female hormones affected female pheromones—affected the female’s smell, her attractivity to the male. The male initiated all sexual behavior.” What science had managed to miss in the monkeys—what it had effectively erased—was female desire.
And it had missed more than that. In this breed used as our astronaut doubles, females are the bullies and murderers, the generals in brutal warfare, the governors. This had been noted in journal articles back in the thirties and forties, but thereafter it had gone mainly unrecognized, the articles buried and the behavior oddly unperceived. “It so flew in the face of prevailing ideas about the dominant role of males,” Wallen said, “that it was just ignored.”
What mostly male scientists had expected and likely wanted to see appeared to have blinded them. Wallen’s career had been about pulling away the blinders. At the moment, below us, one female clawed fiercely at another, bit into a leg, whipped the weaker one back and forth like a weightless doll. Harrowing shrieks rose up. Four or five more monkeys joined in, attacking the one, who escaped somehow, sped away, was caught again. The shrieks grew more plaintive, more piercing, the attackers piling on, apparently for the kill, then desisting inexplicably. Assaults like this flared often; Wallen and his team usually couldn’t glean the reasons. Full battle—one female-led family’s attempt to overthrow another—was rare. That tended toward death: death from wounds and, some veterinarians thought, from sheer fright and shock. Occasionally the compound was littered