This Is Your Brain on Sex (28 page)

When I suggested to Young that this made the study of such effects even more complicated, he nodded eagerly. “It muddies the waters, certainly,” he said. “But it muddies the waters in a way that is representative of how the waters really are.”

Young and Barrett have only just begun this line of research, and Young is careful to point out that even when they finish their work, there will be no hard and fast answer to the question of just who will and won’t cheat—there are just too many variables at play. The sum of this work, however, does offer us a lot of interesting information.

“We’ve shown that a single gene and a variation in that gene can have an impact on something as complex as your relationship with others,” he said. “But that impact may be relatively small and not a very powerful predictor of behavior. I wouldn’t encourage anyone to go out and buy a test to genotype a prospective partner, because it’s going to be wrong most of the time.” He paused for a moment and then added, “Though it will be wrong less [often] than chance.”

So Back to the Question at Hand

What can our brains tell us about infidelity
? Is it neurobiologically hardwired in men? Maybe in women too? If you were hoping for a simple answer—and perhaps an accompanying genetic test or drug therapy to predict or cure the cheating heart—well, neurobiology cannot offer you anything like that at the moment. It is doubtful that it will ever be able to do such a thing. Converging neuroscientific research does suggest that it is highly improbable that all men are cheaters by nature, but it is possible that
some
men, as well as
some
women, have genetic variants due to early environmental exposures that change their brains in ways to make them more likely to stray.

Historically the finger has been pointed at men when it comes to cheating. And considering that old evolutionary imperative argument, it looks as though we still think in those terms. You know the old adage “Men stray, women stay.” But that is just faulty thinking. So if not gender or evolutionary imperative, what does drive a person to cheat on a committed partner? It turns out there is still a lot left to learn, and Zuk says that what science tells us has to be applied cautiously. “It’s easy to look at an individual human and say, ‘Aha! His genes made him do it,’” she told me. “When you talk about powerful men who cheat on their wives, it’s all too easy to say that, evolutionarily, this is just what powerful men do and have always done. That’s just a parody of how evolution really works. No individual is held captive by his genes.” But a better understanding of the way our genes can be shaped by our environment may one day offer us much more useful information.

“People think of genes as being too absolute. When one talks about a ‘cheating’ gene, it’s like any other gene,” said Kim Wallen. “It may create a bias in a certain direction, but it isn’t the end-all be-all. Having a certain variation on a cheating gene doesn’t mean you will cheat any more than having a certain variation on a gene that regulates height means you’ll be tall.” Think about it: even if your family is full of gentle giants, those tall genes will not be fully expressed unless you have the right kind of diet and avoid accidents. Genes are not deterministic.

Still, it is unquestionable that our genes do play a role in the way our brains develop and, in turn, how we behave. It is likely that a better understanding of how vasopressin and oxytocin work their
voodoo on our brains will give us more insight into the neurobiological underpinnings of monogamy. We cannot ignore that the way those genes may be expressed has quite a bit to do with our environment, both when we are children and later.

What did Roger have to say about all this? After I told him about some of the work being done in the field on monogamy, he sheepishly admitted that his father had cheated on his mother before his parents divorced, was more the wandering type, and also happened to be the original purveyor of Roger’s own personal biological imperative theory. “Do you think the way he behaved could have done something to my brain? To my genes and my, what-do-you-call-it, vasopressin system?” he asked.

“Could be,” I replied. “But remember, we’re not slaves to our genes. There is nothing determined about the biology.” I was tempted to tell him that his behavior could also just be a severe lack of judgment on his part that could be handled with a little self-control, but I refrained. Nevertheless, it is clear we still have much to learn about all the ways our genes and brain may influence our behavior when it comes to monogamy. Our early experiences shape how our genes are expressed—which in turn shapes the development of our brains—and influence our behaviors. Even if we could tease apart all the variables and figure out each unique contribution, it is likely we wouldn’t be able to make any generalization beyond what we have now. Every individual is different. We will probably never be able to look at a potential partner and know, definitively, whether he or she might one day stray. We just have to go with our gut and hope for the best.

Chapter 12

My Adventures with the O-Team

Some days I feel like I just cannot get away from
the female orgasm. No matter where I look, it seems the word, with a big flashing letter
O,
is following me around. I see it on the covers of popular women’s magazines in the supermarket checkout line, along with tips and tricks to make it incredible. I hear it discussed in detail at my book club meetings instead of the month’s actual nonfiction selection. It has become the one (and only) topic of conversation for one good friend who has recently started dating a man twelve years her junior. With the recent announcement that a German pharmaceutical company would shut down development of the much anticipated “female Viagra” after a poor showing in clinical trials, the female orgasm is making appearances in both the headline news and late-night talk show jokes.

Never mind that I’m not having all that many orgasms. I’m stuck in the minutiae of an exhausting divorce—not exactly sexy stuff. Getting laid can wait until the lawyers are done conversing, lest I inadvertently give them something else to fuss about. But the rest of the world continues to bring up orgasms at every opportunity.

Ever since Viagra became available in 1998, the world has been clamoring for its female equivalent. In my humble opinion it is the same men who are popping those little blue pills like candy who are actually doing all that demanding. Regardless, both clinicians and pharmaceutical companies seem to be listening. The latest great wet hope was a drug called flibanserin, which acts on two different types of serotonin receptors. It was originally studied for its
antidepressant properties, but when patients reported an increase of sexual events while on the drug, a rarity for those on antidepressant medications, Boehringer Ingelheim, flibanserin’s developer, decided it might have a higher purpose as a drug to enhance female sexual desire.

According to prevalence studies, research that examines how common particular conditions are within the general population, nearly 10 percent of middle-aged women meet the diagnostic criteria for hypoactive sexual desire disorder (HSDD), the fancy clinical name for low sexual desire. Among the
DSM-IV
criteria for HSDD is feeling some distress about the fact that you are not interested in getting busy. HSDD is commonly found in women about to make the “great change of life.” With the success of Viagra in men, female sexual desire drugs seemed to be a seriously untapped market for pharmaceutical companies. After all, who doesn’t want to have more sex? That’s the assumption, anyway.

Unfortunately, no one has been able to find a good drug treatment for HSDD—and not for lack of trying either. Trials looking at a variety of hormones, including estradiol and testosterone, as well as a variety of other hormonal and drug compounds linked to increased sexual desire, have not shown the desired effects in clinical trials. Pun intended. Despite a lot of hype surrounding the effects of flibanserin (and a somewhat obscene amount of money poured into its development), Boehringer Ingelheim decided to halt its attempts to register the drug as an approved HSDD treatment after it showed no improvement in female sexual desire during trials.

Given Kim Wallen’s expertise in hormones, I asked him what he thought of flibanserin’s arrested development. He referenced the Melbourne Women’s Midlife Health Project, a large longitudinal study headed up by Lorraine Dennerstein that followed nearly five hundred women as they transitioned to menopause. The project took every kind of measure you can imagine, including hormone levels, menstruation details, and a variety of different sexual function questionnaires. With such an extensive study, there was hope that Dennerstein and her colleagues might be able to find some kind of hormonal smoking gun linked to decreased desire in this particular cohort. But no such luck.

“You know what was the biggest factor that [Dennerstein] found in terms of sexuality in postmenopausal
women? It was whether they had a new partner. It had nothing to do with hormones,” Wallen told me with a sly smile. Simply stated, human sexual motivation is not just a product of hormones or brain chemicals. There’s a lot more to it: your relationship status, your age, your culture, and just who you happen to be schtupping at the time.

Dennerstein’s findings are reinforced by the results of the most recent National Survey of Sexual Health and Behavior, a large-scale study of sexual and sexual-health behaviors conducted by Indiana University’s Center for Sexual Health Promotion. And not just in women transitioning to a nonreproductive hormonal state. This survey asked nearly six thousand individuals, ranging in age from fourteen to ninety-four, about sexual behaviors and the outcome of their most recent sexual event. The ladies had quite a bit to say about both.

While the headlines about the survey results focused on risky sexual behaviors in the baby boomer set and the fact that more individuals are now reportedly giving anal sex a go, the researchers found something that was very interesting to me. It wasn’t that men overestimate whether their female sexual partner had an orgasm during their most recent sexual encounter. Most women admit to faking a time or two, and most men believe no woman has ever pretended with them. You do the math. I was not even surprised that women who reported orgasm during their last sexual event didn’t stick to straight-up penile-vaginal intercourse, but enjoyed a more varied repertoire of sexual behaviors during each encounter. Another duh, in my opinion. Variety is the spice of life, right? What struck me was that the researchers found that a higher percentage of women reported having an orgasm during their most recent sexual encounter when it was with someone with whom they were
not
involved. Forget commitment. Forget stability. Forget the strength of a long-term relationship where your partner knows you inside and out. Though it is hard to extrapolate exact meaning from survey data, in this case novelty was a better predictor of female orgasm than what every girl supposedly wants: a lasting, loving relationship.
¹

What does this tell us? Simply stated, there is no one thing, no particular hormone level or current relationship status, that sums up a sex drive or one’s level of sexual satisfaction. There are a variety of factors that affect female desire—and even though it
might not always seem that way, male desire too. Despite the fact that the androcentric view of orgasm (the idea that only a man’s big moment really matters in the grand reproductive scheme of things) no longer prevails, the truth is we just don’t know all that much about the nature of “normal” sexual desire. We are not even all that well versed on what happens during an orgasm.

“I have a problem with the term and talking about female sexual dysfunctions,” said Beverly Whipple, a researcher at Rutgers University who has been studying female sexuality for more than three decades. “There’s still a lot we need to know about normative function before we can truly say what’s dysfunctional.”

She, Barry Komisaruk, and other colleagues at Rutgers may not yet be able to define normative function, but they can tell us a lot about what is happening in the body during an orgasm. And quite a bit of it is happening in the brain.

It’s All in Your Head

It is often said that the brain is the most important sex organ. Though it’s a cliché, it’s true; anyone can tell you that it is hard to reach orgasm when you get distracted thinking about what happened at work earlier in the day or wondering if your butt looks enormous. The brain matters—quite a lot. For the past few decades researchers have been working diligently to understand the physiology of orgasm. A great deal of that focus has remained below the neck, on what’s happening with the penis, clitoris, and vagina. However, in recent years neuroimaging studies have shown—surprise, surprise—that the brain plays a huge role in orgasm. You might well think of your brain as one giant gonad. It kind of is, since it’s active even when genital stimulation is absent from the experience.