Rhesus monkeys Deidrah and Oppenheim cuddle at a compound in Georgia where their breeding habits and other social interactions are being studied. (Kim Wallen)

Her unruly red-blond hair tufting atop her head, Deidrah sat beside Oppenheim. 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, 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 120-foot square, was filled with ladders and ropes and assorted apparatus donated by a 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, Kim Wallen, an Emory University psychologist and neuroendocrinologist who has been working for decades at the university’s Yerkes Primate Research Center outside Atlanta, gazed down at the habitat’s 75 rhesus monkeys. This is the species that was sent into orbit in the ’50s and ’60s as stand-ins for humans to see if we would survive trips to the moon.

“Females were passive. That was the theory in the middle ’70s. That was the wisdom,” he remembered from 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 Oppenheim’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.” But what science had managed to miss in the monkeys — and what Wallen and a few others were now studying — was female desire.

And science 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 ’30s and ’40s, 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.”

Long-held biases about lust

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. My visit to Yerkes was part of seven years of reporting about the science of women’s sexuality, a field that has only begun to look beyond the stereotype of long-held distortions about female lust and monogamy that Wallen was describing. Wallen and his primates helped to put things in focus.

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 very rare. That tended toward death: death from wounds and, some veterinarians thought, from sheer fright and shock. Occasionally the compound was littered with corpses.

When he thought about the way science had somehow kept itself oblivious to female monkey lust for so long, Wallen blamed not only preconceptions but the sex act itself. “When you look at the sexual interaction, it’s easy to see what the male is doing; he’s thrusting. It takes really focusing on the entire interaction to see all that the female is doing — and once you truly see it, you can never overlook it again.”

Deidrah fingered Oppenheim’s belly, caressing, desperate to win his favors. He flopped down on his front, inert in a strip of sun. She kissed where she could get access, his ear again. The red of her face bordered on neon.

Bulky and torpid, Oppenheim and the habitat’s other adult male didn’t fully take part in the life of the compound. They didn’t belong to any particular family. They were merely breeders — and their peripheral status mimicked the male rhesus role in the wild. There, in Asian mountains or lowland forests, adult males lurked at the edges of female-run domains. The females invited them in to serve sexually. The males remained — desirable, dispensable — until the females lost interest in them. Then they were dismissed, replaced. In his compounds, Wallen removed the breeders and introduced new males about every three years, the time it took for their charms to wane, for the frequency of their copulations — almost always female-initiated — to fade. In the wild they seemed to stay attractive only slightly longer.

A bias toward novelty

“Rhesus females are very xenophobic when it comes to other females,” Wallen said. “Introduce a new female into the compound and she’ll be hounded until she dies. But when it comes to males, females have a bias toward novelty.”

With his pale muzzle and russet back, Oppenheim loped off once more and Deidrah trailed him. A child of hers, less than a year old, hurried behind her. Wallen’s assistants adored Deidrah. They loved her sprigs of out-of-control hair; they loved her personality, the quiet dignity she emanated most of the time, if not at the moment; and they loved the devotion of her mothering.

A year ago, upheaval in the compound had left her and her children vulnerable. Horribly frightened, they latched onto her and wouldn’t let go. “Literally, she could barely get up and walk without being dragged down by her kids,” Amy Henry, an assistant, said. “She accepted it all with grace. She knew it was her responsibility to reassure them that it was okay. She’s always been a low-key monkey. But she gets very excited when she gives birth. And she gets very attached. I watched her carry her daughter on her back for a long time, right up to when she had a new baby. Not all moms will do that.”

With Oppenheim on her mind, though, maternal instinct was gone; Deirdrah was ignoring the baby, almost as if it were a stranger. She was near or in the midst of ovulation, her libidinous hormones high. She positioned herself in front of Oppenheim, crouched, and tapped a hand on the ground in a staccato rhythm. She tapped like this persistently, the rhesus equivalent of unbuckling a man’s belt. Yet her gesture contained a touch of hesitance. “She’s being careful, because all the females around her are higher ranked,” Wallen said. If they decided, for any reason, that they didn’t want her having sex with him, they and their families might tear and bite her to death.

Wallen’s understanding that rhesus females are the aggressors in sex had begun with a distortion he noticed in graduate school in the 1970s. In cramped cages, where rhesus mating patterns were being observed at the time, males appear to be the natural initiators of sex, because the females’ proximity to them mimics the kind of stalking Diedrah was up to now — tracking that eventually inspires a male to mount. After arriving at Yerkes, Wallen deepened his insight. In the center’s broad compounds, habitats whose size comes closer to conditions in the wild, sex depends almost completely on the female’s signaling, her ceaseless approaching, her lipping and stroking and belly-kissing and tap-tapping, her craving. Without it, copulation probably wasn’t going to occur.

Females as sex hunters

Are females the main sex-hunters in most other monkey species? The answer isn’t yet known, Wallen said; not enough meticulous science has been done. Capuchins, tonkeans, pigtails — he named three types of monkeys whose females are the sexual stalkers. With their sweeping tails and ebony faces, female langurs initiate fervently. And among the massive orangutans, scenes like this were documented, for the first time, in the late ’80s: males lying on their backs, showing off their sexual readiness to females, and waiting passively for the female to mount them. As for bonobos, with their strangely parted hair and reputation for abandon, females avidly get sex going with males — and with each other.

At last, with Deidrah tapping her crazed Morse code on the dirt, Oppenheim reached out. Standing behind her, he set his hands on her hips. And suddenly she had what she sought. He pumped back and forth in a flurry, paused, repeated. At the end, his thighs quivering and eyes going fuzzy, she twisted, turned her face to his, smacked her lips at high speed, reached back to seize him, and yanked him violently toward her.

Her fulfillment was short-lived. Within minutes, she was hounding him again. At other moments, she might have moved on to the other male. “She has sex,” Wallen said, about rhesus females on the whole, “and when he goes into his post-ejaculatory snooze, what does she do? She immediately gets up and goes off and finds another.” Tracking the action of the compound, he asked himself, as he had so many times, whether any of this applies to humans and whether “because of social conventions and imperatives, women frequently don’t act on or even recognize the intensity of motivation that monkeys obey.” His decades of study spanned the human as well as the rhesus realm. He answered, “I feel confident that this is true.”

He didn’t mean to imply perfect correspondence between Deidrah and the average woman. There was too much complexity for that sort of equation. Like lots of current research on human and animal sexuality, Wallen’s work with our close ancestors calls into question conventional assumptions, among them that women have innately lower and less raw sex drives than men, and that while men have been programmed by evolution to spread their cheap seed, to be promiscuous, women, relatively speaking, are genetically compelled to seek out one good man and are at least somewhat well suited to monogamy.

Such notions may be soothing for society — that half the population is somehow biologically designed to serve the interests of stability. But scientists studying female sexuality — from the lusts of Deidrah and other monkeys to the desires of human women, measured in laboratory tests of genital blood flow and explored in longitudinal research covering decades in women’s lives — are starting to suggest that maybe we haven’t allowed ourselves much knowledge about what women want.

Bergner is author of “What Do Women Want? Adventures in the Science of Female Desire,” from which this article is adapted.