But it is important to understand serotonin, too.
Millions of women and men are prescribed selective serotonin reuptake inhibitors (SSRIs), which are the modern form of antidepressants. Women far outnumber men in being prescribed SSRIs. Are these same millions of men and women warned that SSRIs may well send their libido and ability to experience orgasm plummeting? SSRIs produce a state of satiety, due to raised serotonin levels; raised serotonin levels make you feel satiated—which is pleasant—but the same situation reduces your motivation. SSRIs inhibit serotonin uptake: de Contrecoeur found that raised serotonin anesthetizes emotion, suppresses or blocks sexual desire, and makes people sleepier and less aggressive—they even move around less.
On the other hand, lowered serotonin levels raise dopamine activity, de Contrecoeur believes, which in contrast leads people to experience “stimulation of sociability and mood, aggressivity and sexuality.”10
The political implications of these two mood, or mind, states are obvious.
Patriarchal societies, even without the benefit of what current science is now documenting, have, I contend, noticed the link between sexually assertive, sexually self-aware women—and focused, motivated, energized, biologically empowered women.
This is why I call dopamine the ultimate feminist chemical. If a woman has optimal levels of dopamine, she is difficult to direct against herself. She is hard to drive to self-destruction, to manipulate and control.
Other neuroscientists and evolutionary biologists are also confirming that something significant to mood happens in the brain when a dopamine rush prepares the way for orgasm. After orgasm, gender differences emerge. For men, dopamine drops drastically after orgasm, and men lose interest in sex, for a time. They have a refractory period during which they can’t get aroused. But does dopamine drop as far in the female brain—and does prolactin step up the “enough already” response for a woman in the same way, especially if she is multiorgasmic? Not necessarily. If a woman goes on to have another orgasm and then another, she will continue to mainline boosts of dopamine. And new research shows that virtually all women are able to have orgasms fairly easily under the right circumstances.
Why does this matter? Because it suggests that all women who are orgasmic (and especially women who are able to be very orgasmic) have the capability to receive much more dopamine, and more opioid boosts, over the course of a really good day than the men they have just slept with, and more than other women who lack knowledge about their own sexual pleasure.
I asked Dr. Pfaus, “Wouldn’t more female orgasms trigger more opioid release?”
“It might well do that,” he said. “For women who have multiple big ones, you would expect them to have more opioids.”11
Female orgasm also, surprisingly, boosts the levels of testosterone in women. That is one more reason that great sex makes women hard to push around easily. Science writer Mary Roach points out that testosterone “more than any other hormone . . . influences a woman’s libido” and also makes women want to have more sex.12 So sex raises women’s testosterone, which in turn raises their libido further, which in turn makes them more assertive and more interested in having even more sex. (This connection is well documented; testosterone therapy, for instance, a controversial menopause treatment for women, raises women’s assertiveness levels as well as their libido.)13 So the fear that patriarchy always had—that if you let women have sex and know how to like it, it will make them both increasingly libidinous and increasingly ungovernable—is actually biologically true!
I don’t like any kind of feminism that sets one gender above another, so I do not mean this in any way as a value judgment. Neither gender is “better.” But one gender is theoretically able to get more of a certain kind of dopaminic and opioid activation during sex, which has a very specific effect on the brain and even the personality. We cannot escape what this math implies for female sexuality, in its unmediated, un-messed-up state: nature constructed a profound difference between the sexes, which places women in, potentially, a position of greater biochemical empowerment than men, through the medium of satisfying sexual activity. (Of course, it is not a zero-sum game: men have other ways of getting extra dopamine hits.)
The good news is that all this dopamine will—if women and their vaginas are not hurt, suppressed, injured, or demeaned—make women more confident, more euphoric, more creative, and more assertive—possibly more than a male-dominated society is comfortable with. Feminists are continually seeking to elicit the suppressed female “voice.” Serotonin literally subdues the female voice, and dopamine literally raises it.
Dopamine causes focus and initiative, according to science’s latest model. Opioids cause bliss, the “oceanic feeling,” the sense of the sublime. Have you ever seen a group of people who have just snorted cocaine talk? You can’t shut them up. Cocaine causes these effects by stimulating dopamine release in the brain; indeed, cocaine was first abused by Dr. William Halsted at Johns Hopkins Hospital because it made him feel invincible, filled him with energy and confidence, and fought his fatigue.
How many heterosexual women reading this can remember a time when you made love and found yourself afterward mysteriously suffused with chattiness, just at the moment your male lover was crashing into sleep? You just wanted to talk. You had so much to say! Studies show that an embarrassing number of women confess to having woken up a sleeping male partner to speak with him. If you have done that, you know who you are—though you may not have known why you had that intense drive to do so. That is the unstoppable sociability of dopamine, in the anticipation of one more orgasm.
To restate what by now should be obvious: the healthy, sexually well-treated vagina regularly delivers a strong activation of dopamine to the female reward system, as well as surges of oxytocin for connection, and opioids that drive the sensations of joy. So the vagina delivers to women the feelings that lead them to want to create, explore, communicate, conquer, and transcend. And since women can potentially have more orgasms than men, theoretically, and can theoretically release more oxytocin in lovemaking, they risk also feeling more: more love, more attachment, and more affection afterward.
Let’s look at oxytocin—“the cuddle hormone”—on its own. Oxytocin’s function in humans is to bond people to each other so they are better able to survive. Oxytocin also allows people to see the relationships between things and between people more clearly. David J. Linden reports that nasal oxytocin sprays that were designed to help new mothers release milk for lactation—the brand is called Liquid Trust—have been put to other uses. Those who inhaled the spray became more trusting of strangers, even after they had been betrayed in a game. They were more willing to take greater social risks. They were also more likely to see “the connections between things,” meaning, in this case, they were better able to infer others’ emotional states. In a famous experiment, oxytocin helped subjects correctly intuit another person’s emotional state—when the subjects were given photos of human faces in which only the eyes were visible.14
Oxytocin is women’s emotional superpower. Oxytocin induces labor contractions and helps release breast milk, as we saw; its evolutionary role is to bond us to our children and to our mate long enough to maximize the chances that a child will have two caregivers during its long dependency.15 In experiments, when scientists block either oxytocin or dopamine, mother mammals will ignore their offspring. It reduces cravings.16 When scientists administered it to rodents who were addicted to cocaine, morphine, or heroin, the rats opted for a lower level of the drugs and showed fewer symptoms of withdrawal.17 “Oxytocin and its receptors appear to hold the leading position among the candidates for the substance of ‘happiness,’ ” assert Navneet Magon and Sanjay Kalra in “The Orgasmic History of Oxytocin: Love, Lust and Labor.”18 Oxytocin also calms—one rat injected with oxytocin will calm down a whole cage full of anxious rats.19 It increases sexual receptivity.20 It is not so surprising that when the neural pathways from brain to vagina are damaged,
one feels that life has less meaning; truly, the well-treated vagina is a medium that releases, in the female brain, what can be called without exaggeration the chemical components of the meaning of life itself.
IS THE VAGINA AN ADDICT?
During that month I have been completely happy. . . . What joy, dear, to find your letter. . . . I won’t say I need it desperately, because that is my chronic state. . . . Before that [happy hour with you] I had no personal life: since then you have given me all imaginable joy. Nothing can take it from me now, or diminish it in my eyes . . . [it] has set my whole being free. . . . I can’t say this to you because when I do you take me in your arms et alors je n’ais plus de volonte. . . .
—Edith Wharton to Morton Fullerton21
So dopamine makes you confident and gives you faith in rewards; opioids provide addictive boosts of happiness and good feeling; oxytocin, which studies have shown is increased upon orgasm, and so women who are multiorgasmic can theoretically produce more of than men, makes you bond, feel affection and trust, and leads you to want to make love some more.
Could this explain why, even though most actual sex addicts are men, so many women feel at times that they are “addicted to love”? Our highs are potentially higher; but the downside is that when that dopamine and opioids leave our systems, we are potentially in a lower low than most men experience—a withdrawal state that is exactly like opiate withdrawal. The biochemistry of addiction means that if we have more of a dopamine burst to start with, our fall will be that much harder. So women have more of a tendency to be mystics than men—because of all this potential dopamine production—and more of a risk of being sexual love addicts (to distinguish from straight sexual addiction, which men are more often treated for). The higher rates of oxytocin and dopamine that we can potentially produce—and potentially painfully lose—potentially make us dependent on our love/sex object in ways that may not always be mutual.
I turned once again to the scientists.
I interviewed Dr. Jim Pfaus in his lab at Concordia University in Canada. Dr. Pfaus is a pioneer in the study of new frontiers of female sexuality. He noted that it was reasonable to see a connection between female orgasm, dopamine activation, and heightened focus and confidence.
I was lucky to witness an extraordinary experiment in this lab, as Dr. Pfaus and his team of graduate students demonstrated the role of female sexual pleasure in mate selection. This jaw-dropping experiment would be published in March of 2012 in the Archives of Sexual Behavior as “Who, What, Where, When (and Maybe Even Why)? How the Experience of Sexual Reward Connects Sexual Desire, Preference, and Performance.”22
Dr. Pfaus himself is a youthful-looking scientist with an energetic demeanor, who wore, in his off hours, a casual T-shirt, boots, and a black leather jacket. Dr. Pfaus’s lab was in a pleasant modern quadrangle on the Concordia campus, which is in a handsome red-brick suburb on the outskirts of the relaxed and intellectually curious city of Montreal. In a brightly lit, cheery lab with stacks of well-tended male and female rats in clean plastic cages lined up against the walls, Dr. Pfaus introduced me to his even more youthful, highly focused team of researchers, at least half of whom were women.
Then, before my eyes, Dr. Pfaus and his team proved the role of female sexual pleasure in mate preference among lower mammals—the role of the pleasure-seeking vagina, clitoris, and cervix in the evolutionary dance.
One female scientist gently lifted up a “naive” (that is, virgin) black-and-white female rat and showed me, while stroking her, how she would be injecting the animal with naloxone to prepare her to not have a good time for the first sexual experience of her life. I could have imagined it, but as we both watched the adolescent virgin rat scramble about curiously after her injection, a hint of melancholy, from me and from the young scientist watching her subject, was in the air.
While one group of sexually naive female rats was injected with naloxone, which blocks the experience of pleasure, a control group of virgin female rats was injected with saline, which does nothing. All the rats were injected, too, with hormones that made them ovulate, ensuring that they would, under ordinary circumstances, very much want sex.
The female rats were then placed into cages designed by a female scientist: the cages had four little openings in a Plexiglas divider. These allowed the female rats to scamper in and out of the area where the male rats were waiting for them (since the males are bigger, the males could not follow the females through the little doors). The doors gave the females control over the contact.
The female rats injected with the saline—that is, those who could feel pleasure—were—there is no other way to say it—wildly flirtatious; they scampered in and out of the males’ space; they “solicited” the males repeatedly (I learned that female rats solicit males by making a “headwise orientation”—gazing directly into the males’ eyes—then running away); they hopped around the males, another sign of female rat sexual desire; they presented their genitals to the males to lick and sniff. One feisty female kept trying to mount the male in her cage—finally reaching a point at which she simply resorted to hopping onto his shoulders and mounting his head. What was unmistakable about the activity was that it was being reinforced—the “saline” females were getting something they wanted from the males that made them more and more interactive with them, and more and more excited. For the saline group, it was prom night. Excitement, activity, interaction!
For the naloxone females, in contrast—they all soon looked like characters in an Ibsen play. There was some initial sniffing and palpating from the males, but soon the females just gave up responding to, or initiating, contact. You could see the moment at which they did, almost perceptibly. After a few forays, they stopped interacting with their partners; stopped scampering over to the male’s sides of the cages; stopped “headwise soliciting”; stopped trying to climb onto the males. Soon each female was gazing bleakly into the middle distance in her own area in the cage that the male could not get to—though one male, I will never forget, was desperately trying to get himself through the too-small doorway and, in a begging posture, tried to drag his mate through the tiny door by her tail with his teeth. Finally the females were permanently on “their own side of the bed.” They stopped moving much at all—wouldn’t look at the males—and appeared listless. They were not being reinforced by sexual pleasure. What struck me about that scene was not just that sex wasn’t being reinforced for these females—but that nothing, really, was being reinforced; they weren’t interacting with their own environments.
The experiment in its later stage showed an even more dramatic outcome: at this point, the scientists ran the naloxone experiment with a scent—such as lemon or almond—associated with the male rat: the scent was placed into the male rat’s fur. Later, when the young, naive female rats who had had naloxone were put in a “ménage à trois” situation with two male rats as potential sexual partners—that is, in a situation in which the females could choose—they avoided the male rat that was scented with an aroma, even if it was a new male rat—and even though these females now could experience pleasure. In other words, the females were showing proof of memories of a bad sexual experience, and making decisions accordingly. Dr. Pfaus noted that they showed a lot of activity in the prefrontal cortex during that experiment: it proved that even lower female mammals have sexual memories and think about avoiding bad—pleasureless—sexual experiences. In strikingly poetic language for a scientific journal, he writes that his experiment proved “that a critical period exists during an individual’s early sexual experience that creates a ‘love map’ or gestalt of features, movements, feelings, and interpersonal interactions associated with sexual reward.”23
I left the lab that day feeling strangely validated and elated by what I had seen (though glad that the naloxone rats would get a chance to have the saline in the future). Nature had spoken. Those females in the first experiment—the saline group, so eager for sexual pleasure that they were mounting the head
s of the happy males—were, as Dr. Pfaus points out only partly joking, making decisions in an environment in which no one had ever called them sluts, or unladylike. I felt strangely freed by seeing how directly nature or evolution had placed that intense female sexual desire firmly inside every little female mammal on earth.
A THIRD SEXUAL CENTER FOR WOMEN?
Sexuality is under observation in many labs, and experiments are producing much new information about female arousal, desire, and emotions.
I was interested to note that Dr. Pfaus’s other recent experiments show that female rats, given the option, prefer penetration (that is, penetration that they can control)—with clitoral, vaginal, and cervical stimulation—to the “brush” that stimulates the clitoris alone.
The latest MRI experiments from Dr. Barry Komisaruk’s lab at Rutgers University in 2012 confirm a possibly related finding in human females, too. The vagina and the mouth of the cervix seem to be evolutionarily rigged to need an “other.”
Dr. Komisaruk’s MRI study showed that genital stimulation (clitoral, vaginal, and cervical) in women activated different but adjacent parts of the cortex, and that these areas also relate to different functions and emotional centers. This experiment confirmed in a vivid new way—among other amazing hypotheticals—the existence of a third sexual center for women, this one at the mouth of the cervix.24 (Beverly Whipple’s experiments had provisionally identified it in the 1980s.)
The idea of another sexual center in women made perfect sense to me. I had experienced it myself, even though, according to our until-recent understanding of the anatomy of female orgasm, it was not supposed to exist. It makes evolutionary sense, of course; while it is handy from an evolutionary point of view for women to have clitoral pleasure, it is superefficient, for reproductive reasons, for women to experience additional extreme pleasure from pressure at the very mouth of the cervix, as that kind of pleasure encourages penetration and thus pregnancy. I was also aware that for many women, when there is sexual pressure against the cervix, orgasms can feel far more emotional—women can burst into tears after orgasms that strike the mouth of the cervix. Many women have described to me becoming emotionally “addicted” to this sensation from a lover.