Zietsch replies — still no good evidence the female orgasm is adaptive

I criticized the Zietsch and Santilla paper on the female orgasm. Now one of the authors has responded.

One response he makes is that some of the limitations to the study that I pointed out were also explicitly recognized in the paper. This is true; however, my purpose in mentioning them was to highlight the fact that they make it impossible to draw even the tentative conclusions the authors do…which obviously is not something that was done in the paper. Admitting that assessing orgasmic function with self-reports, for instance, is a limitation doesn’t really change the fact that extremely weak evidence was published to support a particular hypothesis.

Another problem I raised is that the comparisons between male and female orgasmic response were inappropriate. They compared the timing of male orgasm to the likelihood of women having an orgasm at all. My objection is two-fold: they are using phenotype as a proxy for a genetic difference, which is problematic in a trait so strongly responsive to an environmental difference, and it treats two parameters, timing and likelihood, as equivalent in men and women. I don’t think these are necessarily directly connected at all. Zietsch’s reply emphasizes that he does think this is a valid comparison.

Indeed, we measured susceptibility to orgasm in response to sexual stimulation (let’s call it ‘orgasmability’) by assessing the likelihood of orgasming during sexual activity in women and the time taken to orgasm during sexual activity in men. That’s because during sex, men tend to reach orgasm faster than women and generally cannot continue once it is reached. Even when women reach orgasm faster than their man, they can generally continue intercourse until he reaches orgasm, sometimes achieving more orgasms. As such, women’s orgasm during sex is time limited – if she doesn’t reach it in relatively quick time, she might not have it at all, whereas men can go until they finish. That’s why we measure likelihood of orgasm in women and time to orgasm in men, consistent with countless other studies and definitions of orgasmic ‘dysfunction’ in men and women in DSM-IV.

How odd. If sexual activity is limited mechanically by the maintenance of the man’s erection, then yes, it would be true that women’s orgasm during sex is time limited. However, given that vaginal intercourse and female orgasm are only weakly connected, isn’t this an unfortunately male-centered perspective? I will confess that personally, if my sexual performance were measured only by time to orgasm, I’d be considered a pathetic lover (admit it, all you guys reading this: it’s true for you too), but somehow my sexual encounters go on considerably longer, to the delight of both participants. Human sexual activity is considerably more complex than wham-bam-thank-you-ma’am, as I’m sure Zietsch knows.

It’s also a self-destructive assumption. Was there ever a time in our evolutionary history when sexual interactions were limited by male time-to-orgasm? I suspect not; caveman/cavewoman sex probably involved a fair amount of courting and cuddling and playing, just as it does nowadays. And if it didn’t — if it really were nothing but 3-to-5 minute intromission and ejaculation sessions — then there was no opportunity for female orgasm to be selected for. So this is really all an irrelevant objection.

Also…extremes in variation in the timing of the male sexual response are considered dysfunctional because they deviate far from a solid norm. A man who takes a half-hour of focused stimulation to achieve orgasm is probably experiencing some real problems. A woman, on the other hand, who takes that long is not that unusual at all; she is not ‘dysfunctional’. She is normal. It’s a problem when your study assumes that a stable, normal, healthy condition in a woman is comparable to a dysfunctional condition in a male.

Now one central explanation I offered was that male orgasmic response was strongly canalized — that is, there had been selection for multiple genetic processes keying on a strong environmental cue, the presence of testosterone, that made the male response much more robust. The byproduct hypothesis postulates that the female orgasmic response uses the same genetic circuitry, but is more weakly expressed because the cue is largely missing. Unfortunately, we seem to be arguing past each other.

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