Erotic Plasticity

I’ve just read two books about sex (Sex at Dawn, and Perv), and the same fascinating study, about something called “erotic plasticity,” was mentioned in both.

In 2005 psychologist Meredith Chivers set up an experiment where she showed a variety of sexual videos to heterosexual and homosexual men and women. The videos depicted a wide variety of activities covering various sexual combinations: male/female, male/male, female/female, female alone, and man alone. At the end, just for the hell of it, she threw in one of bonobos mating. The subject’s genitals were wired to measure blood flow (an accurate indicator of arousal) and the subjects also indicated how turned on they felt with a keypad.

Men were consistent—if they were heterosexual the naked women turned them on but the men did not, and if homosexual, vice versa. The bonobos didn’t turn any of the men on. In addition, the men’s reported feelings matched their genital blood flow.

But women responded genitally to everything—even the bonobos! However, they didn’t report being turned on to everything. They only acknowledged arousal about a subset of videos.

This is interesting enough, but there’s more. It would be easy to conclude that this is just a strange human quirk. But another study, done in 2001 with goats and sheep, shows the same erotic plasticity difference between males and females.

In the study by Keith Kendrick, baby goats were given at birth to sheep mothers, and lambs were given to goat mothers. They were strictly segregated from any contact with their own species. When they were reproductively mature, the animals were brought into groups of mixed sheep and goats, of both sexes. The males of both species showed no interest in the females of their own kind. They only wanted to mate with the species they’d been raised with: goats with sheep and sheep with goats. Females were different: they’d have sex with either species.

In other words, erotic plasticity is a phenomenon that extends beyond humans.

In a further confirmation, social psychologist Roy Baumeister did a meta-study of fifty years of data on sexual differences between men and women. He wrote, “Once a man’s sexual tastes emerge, they are less susceptible to change or adaptation than a woman’s.”

Some of his examples were: in reports about group sex, women would almost always perform cunnilingus on the other women, but heterosexual men wouldn’t perform fellatio on the other men; women in general are more likely to call themselves bisexual than men are; women are more likely to change between hetero and homosexual during lifetime; and lesbians are more likely than gay men to say their sexual orientation is a “choice.”

What does all this mean?

First, why would women be so flexible? Ms. Chivers suggests that this is an adaptive response by women to avoid injury while having sex. Her “preparation hypothesis” posits that being easily aroused reduces physical injury to a woman’s reproductive organs; the vagina is lubricated on the least suggestion of sex. As a woman, this makes sense to me. It also explains some very odd female responses, for instance, why some women experience genital arousal to the idea of rape, even when they find it abhorrent consciously.

Second, how awful for men! Sex at Dawn summed up the studies like this: “Young males pass through a brief period in which their sexuality is like hot wax waiting to be imprinted, but the wax soon cools and solidifies, leaving the imprint for life. For females, the wax appears to stay soft and malleable throughout their lives.”

An unusual sexual proclivity is called a “paraphilia,” which is defined as “a condition in which a person's sexual arousal and gratification depend on fantasizing about and engaging in sexual behavior that is atypical and extreme.” (Of course we could have a conversation about what “atypical” and “extreme” mean—who’s making these rules up? From my point of view, mainstream American’s idea of “typical” and “normal” is pretty narrow and boring.) Common examples of paraphilia are: pedophilia, exhibitionism, sadomasochism, and fetishism.

Many sexologists believe that a specific event, or perhaps a series of events, in a man’s early boyhood—between five and ten years old—imprints him with a specific “erotic target” that then becomes his paraphilia. Say a little boy has an erotic experience when he’s sitting on a woman’s ankle as she swings her leg—and he develops a boot fetish (see the movie R. Crumb for a description of this). Or a little boy is playing outside with a friend who dares him to take off his clothes and then rubs his penis; he feels aroused—and he becomes an exhibitionist.

Sexologists tell us that over 99% of the people with a paraphilia are, of course, men. Women are too flexible to become locked into any one sexual behavior as the only act that will arouse them. “Only” is the important word there. A woman might enjoy sex that includes exhibitionism, or sadomasochism from time to time, but she is much less likely to be exclusively interested. But a man who is a paraphilac can only be aroused when sex follows his script.

Jesse Bering, the author of Perv, makes the compassionate observation that if it is true that men are imprinted with a sexual proclivity and it is hard-wired in their brains, then this is their sexual orientation. It’s not a choice. We can’t hate pedophiles, for instance. They didn’t choose to be that way.

 Third, Mr. Bering argues that this knowledge should makes us rethink sex-ed:

Most of us see four- to nine-year olds as asexual, but if this is indeed when irreversible male sexual imprinting occurs, our denial that children have any capacity for sexual feelings may actually increase the odds of us brewing deviant little darlings. 

…As a consequence of our enshrouding sex in mystery and the forbidden, children sense a conspiracy of silence regarding unspeakable acts and untouchable parts, and sex, ironically, is therefore made all the more salient and attention-getting to them. With adults seemingly hiding something so gravely serious and ever so important, the enigma only widens. Wherever they look, they’re reminded of this shadowy unsolved ‘problem’ that nobody talks about and which, therefore, keeps nipping away at them. 

...Because of this silence, “the child’s ostensibly ‘sexless’ world is, in reality, to them over-sexualized in cryptic ways. Perhaps when paired with a genetic predisposition for sexual imprinting, some little boys’ nagging cognitive efforts to solve the grand riddle therein will seep into parts of their environment that wouldn’t otherwise be sexual. These misplaced sex cues can inveigle deep into brain networks linked to their arousal, and voila, a paraphilia is born.

Fourth, I think these studies can also explain some of the difficulties men and women experience in connection with sex. Men are very aware of what they want and what turns them on. Women are much more ambiguous. Men have always assumed this was because women weren’t being honest with themselves, but it turns out that this is an aspect of female physiology. As the authors of Sex at Dawn put it: “It could well be that the price of women’s greater erotic flexibility is more difficulty in knowing—and, depending on what cultural restrictions may be involved, in accepting—what they’re feeling.” It certainly helps me to make sense of some of the issues I have faced in my sexuality.

Neither book discussed any further research in this area, in particular how to help men move past their imprinting. Hopefully someone already has this research underway.

Notes:

Sex at Dawn, by Christopher Ryan and Cacilda Jetha, [2010, HarperCollins]

Perv: the Sexual Deviant in All of Us, Jesse Bering [Scientific American, 2013]

Meredith Chivers, “A Brief Review and Discussion of Sex Differences in the Specificity of Sexual Arousal,” Sexual and Relationship Therapy 20, no. 4 (2005): 377-90

Keith Kendrick et al., “Sex Differences in the Influence of Mothers on the Sociosexual Preferences of their Offspring,” Hormones and Behavior 40, no. 2 (2001): 322-38

Roy F. Baumeister, “Gender Differences in Erotic Plasticity: The Female Sex Drive as Socially Flexible and Responsive,” Psychological Bulletin 126, no. 3 (2000): 348