It’s everything you wanted to know about sex but didn’t know to ask.

In the new book “What Do Women Want? Adventures in the Science of Female Desire” (Ecco), author Daniel Bergner upends long-standing myths about women and sex — everything from the nature of attraction and pursuit to the prevalence of taboo fantasies to monogamy itself.

“Women are supposed to be the standard’s more natural allies, caretakers, defenders,” Bergner writes, “their sexual beings more suited, biologically, to faithfulness.”

The long-standing thinking holds that men are more promiscuous by nature because they’re biologically programmed to spread their seed, while the risks of pregnancy and child-rearing cause women to be more selective.

“We hold tight to the fairy tale,” he writes. “We hold on with the help of evolutionary psychology, a discipline whose central sexual theory comparing women and men — a theory that is thinly supported — permeates our consciousness and calms our fears.”

It’s telling that, in our post-“50 Shades of Grey” era, some of these findings surprised even the field’s leading researchers. Here are some of the most unexpected ones:

Domination

The results of 10 separate studies so rattled sexologist Marta Meana that she was initially hesitant to talk about them: Between 30 and 60 percent of women reported frequently having what’s been termed “rape fantasies,” and many of the women who described their own daydreams were also disturbed. “If I truly believed in women’s equality with men,” said one, “then I’d have to have sex and imagine sex that reflected that — no domination, no rape fantasies. One result was that I married a nice liberal man who shared my convictions on how sex should be. Seven years later we divorced.”

Most experts believe that the number of women who have so-called rape fantasies is actually much higher, but the notion and nomenclature is so taboo few are willing to admit to it. One theory holds that the fantasies actually dial into female narcissism, the notion that one is so unbelievably desirable that a man — whether a professor or family friend or stranger — is so overcome with longing that he loses control. After Meana’s findings were reported in a magazine, she was deluged with e-mails from women, some accusing her of promoting and excusing rape, others expressing gratitude for finally breaking the discussion open. She was booked on “Oprah” and was relieved to see a wholesome, middle-aged woman talking about her own version of the fantasy.

“There were lots of messages from high-powered women thanking me for allowing a discussion of elements of sexuality that don’t fall neatly into an ideological box,” Meana says in the book. “One woman, in the art world in New York, told me, ‘I could not say what you said without feeling shamed, as though my eroticism made me a willing participant in a patriarchal system.’ ”

Another subject, called Ndulu, talks about her own submission fantasy, being pulled into a room and pinned against a wall by an unknown man while he has his way with her. Yet when she found herself, in reality, summoned to a bathroom by a good-looking stranger who then locked the door and became aggressive, she panicked and fled. This was not what she actually wanted. In her fantasies, she was in control, and that is the point experts, for obvious reasons, stress most.

“I hate the term ‘rape fantasies,’ ” Meana says in the book. “In fantasy, we control the stimuli. In rape, we have no control. They’re really fantasies of submission.”

DESIRE

It’s long been believed that women need to feel emotionally connected in order to feel attracted, to want sex. But a recent study by sexologist Meredith Chivers shows that when it comes to desire, women are as visually stimulated and more easily turned on than men.

A group of straight women were hooked up to a device that measures genital blood flow and listened to a series of tapes in which pornographic scenarios were described: couplings between men and women, women and women, strangers. The subjects reported feeling most aroused by sex between people in long-term relationships, but the machines reported the opposite — blood pulsed faster during sex between strangers.

These findings tracked with another study in which women watched both gay and straight porn and were aroused by every conceivable scenario, while straight men were aroused only by women, gay men only by men. Chivers theorizes that the gap between what women self-report and what actually happens to them physiologically is a byproduct of socialization — that women don’t feel as much permission to be as open as men do. Her colleague Terri Fisher at Ohio State agrees. “Being a human who is sexual, who is allowed to be sexual, is a freedom accorded by society much more readily to males than to females,” she says in the book.

PURSUIT

The study of sexual aggression in female rats and monkeys is relatively new. Up until about 40 years ago, scientists only focused on how they performed during sex. Mating rituals in both species, it turns out, show that females are far more aggressive in the pursuit of males than had ever been suspected. A landmark study by Martha McClintock reported not just rat flirtation — female rats engage in a sort of coy physical approach to males, moving closer and pulling away over and over — but, when faced with an indifferent male, do not give up. One female rat in McClintock’s study actually climbed a disinterested male and began pounding away from behind — and when the females succeed, they make sure to constantly push away the male during sex in order to keep it going longer.

Female monkeys are equally tenacious. Bergner writes about Deidrah, a monkey who lives among a studied community at Emory University. Deidrah is described as a dignified young mother devoted to her babies — but whenever she is in the vicinity of a male named Oppenheimer, she becomes monomaniacally focused on him — her face goes red; she chases him; she pats his chest repeatedly, which is the height of sexual aggression, until, finally, he has sex with her. Kim Wallen, the neuroendocrinologist leading the study, believes scientists overlooked female aggression because when they observed sex itself, the females always seemed more passive. “When you look at the sexual interaction, it’s easy to see what the male is doing; he’s thrusting,” Wallen says. “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.”

MONOGAMY

Here, too, conventional wisdom has long held that women value monogamy more than men, for reasons both practical, such as child-rearing, and emotional. Yet recent studies indicate that women have as complicated a relationship with monogamy as men do. In the study of rats, for example, females who have just copulated start running around in search of other males to have sex with; the theory is that they’re hunting for the best sperm. In monkeys, the same behavior is prevalent, and scientists believe that it’s a form of protection: Some male monkeys commit infanticide if a baby gets in the way of sex, but only if it’s not their baby; keeping the paternity a mystery means the baby monkeys have a better chance of survival. Versions of this play out in spiders, dogs, birds.

The research into human relationships is fairly new, but one study of long-term couples showed that, for women, lust dissipated faster than it did for men, and that when the men tried to be more domestic and considerate, it only turned the women off further. A leading researcher believes a key component of lust is distance and difficulty, the tension of not quite knowing whether this new person wants to sleep with you; living together for years blunts all of that.

Scientists also believe women may be built for more sex with more partners. The penis has half the nerve endings of the clitoris, and the ability of women to have multiple orgasms may be nature’s way of encouraging her to seek out more and better sperm. In light of this, Kim Wallen, the scientist who works with the monkey Deidrah, thinks that we may need to re-evaluate what women want. “The idea that monogamy serves the natural sexuality of women,” he says, “may not be accurate.”

The hunt for a female equivalent of Viagra is about 15 years old, and the problem is two-fold: There is, of course, the nature of female sexuality, which is far more complicated than it is for men. But there is also a cultural stigma that makes some psychiatrists nervous, and there have been coordinated campaigns — one led by a professor at NYU named Leonore Tiefer — to squelch research and development. The argument? It would endanger women emotionally — turning them into base, lust-driven creatures — and physically. As one female clinician says to Bergner, “There are already enough date-rape drugs around.”

Far more sexologists and researchers believe that it’s just a matter of time, and that there are only upsides to a drug that enhances libido and pleasure for women — not the least of which could be increased intimacy with their partners, which could actually have the effect of reinforcing, rather than undermining, monogamy.

Yet so much research into the sexual lives of women is vastly underfunded, in part because it remains such a taboo. Not much progress has been made since the days of Kinsey and the Hite Report. And as Bergner points out: How much sense does it make to only understand one half of the equation? “Eros lies at the heart of who we are as human beings,” Bergner writes, “yet we shun the study of our essential core, shun it perhaps most of all where it is least understood, in women.”