Today's post comes to you courtesy of Denim and Tweed, where Jeremy brought up this question, and cited his works very well! And after I saw all that stuff on clitorises, I had cover it myself.
Poor female orgasm. It's always been up for debate. From issues over the G Spot to issues of what it's FOR, the female orgasm has had a rough go of it. Evolutionary biologists have debated the "purpose" of the female orgasm for a good long while. They have debated WHAT the purpose is, to be sure, but even more so, they have debated whether there IS one. Is the female orgasm just an evolution byproduct? No one can deny the importance of the male orgasm in keeping the human species going through the generations. For the good of the species, man must cum. Even with the newfound glories of IVF, some guy, somewhere, had to shoot a wad to get the whole thing going.
(You know, that thing. Source.)
But while the clitoris is anatomically analogous to the male penis...what about the orgasm? A man's orgasm must serve a function, but female? Well, it's not required, and many people take this, and the fact that a lot of women do not generally orgasm during vaginal intercourse, to mean that female orgasm may not really mean much. And so some people believe that it's just an evolutionary byproduct, something like the appendix (well, we used to think that, but apparently the appendix may help with things like gut flora), only more fun.
But others disagree. After all, female orgasm releases a lot of important chemicals, including things like oxytocin and dopamine, among others. Oxytocin has been implicated in pair bond formation, which could be a useful function to make sure a woman doesn't go haring off which some other guy. Other scientists have hypothesized that female orgasm produces some sort of "suction" which pulls semen up into the uterus, but those findings are up for debate. There are even hypotheses that the female orgasm can be used to assess the quality if your mate (well, at least we know whether he's quality in bed...).
But if the female orgasm served a function...how would you TELL? What do you look for biologically to figure it out? I mean, with male orgasm, the function, or at the least the results, are rather obvious. But female? Not all females ejaculate (in fact, most don't), so that's hard to look for. And how would you tell that female orgasm is not just an evolutionary byproduct?
These scientists looked to the clitoris. The idea was that, if female orgasm (in this case I guess they just mean clitoral orgasm) was REALLY an evolutionary byproduct, then the size of the clitoris would not be important, as it would just be a somewhat analogous structure to the male. So then, it would not be subject to natural selection. And if it's not subject to natural selection, they hypothesized that the size of the clitoris would be more VARIABLE than the size of the penis. If the clitoris wasn't necessary, some women might have large ones, but others might have extremely small ones, and it wouldn't make a difference.
Now you could just measure length of the penis, and length of the clitoris, and measure variability. But is that really accurate? These authors didn't think so, and so resolved to look at both length and width, and thus to calculate volume. Previous studies had looked at just length, and determined that the length of the clitoris infect varied more than that of the penis, and determined that, therefore, the whole thing, including the orgasm, was a vestigial organ. The author of this paper disagreed, and turned his attention to volume. And got this:
What we're interested in here is the "pCv" the coefficient of variation. Basically, this author, as far as I can tell, didn't take any data of his own, or at least there are no methods (and one would REALLY have to assume you need big patient consent forms for this sort of thing). Instead, he took data from OTHER studies studying penile and clitoral length and volume. He determined (see the p values) that while clitoral length is more variable than penile length (p=0.02), the variability of the VOLUMES is not significantly different (p=0.17).
From this he concludes that, since the variabilities are not different, the clitoris must be subject to evolutionary pressure, and thus orgasm must have a function.
So first off, I'm ALL FOR female orgasm having a place and function in life. I mean, it would make the orgasm so...hollow...if it didn't have a purpose.
But this paper doesn't convince me of anything.
First off, since when is clitoral volume a measure of female orgasm? Women with bigger clitorises do not have more orgasms, and men with smaller penises certainly have no trouble getting off. Not only that, but men with smaller penises actually aren't any evolutionarily worse off than men with large, and I have to assume the same is true for women (if not more so, esp since the size of the clitoris has never been shown to be related to female orgasm). So what does this study really SAY?! All it says to me is that the size of the clitoris and the size of the penis vary a good bit. But the variances are not different. OoooOOOooo. You know, you probably coulda told me the same thing about male and female nose size, ear size, finger volume, and the size of the friggin' appendix, and I would have nodded sagely and believed you. What does that MEAN?! At least with nose size, ear size, or finger volume, there's a definite correlation with function (the jury is still out on the appendix).
Secondly...dude, get your data. I don't believe the study of the guys you criticized...but I don't believe you, either. Get some data with clitoral volume (and heck, volume of the labia majora and minora while you're at it), and correlate the whole thing with the number of orgasms women have. Come back, show me THAT data. We might be getting somewhere. But what you'd REALLY have to do then...is show me the function of female orgasm. I'd like to believe it has one, but I'm a good scientist and I ain't gonna call it until I have the data.
Lynch, V. (2008). Clitoral and penile size variability are not significantly different: lack of evidence for the byproduct theory of the female orgasm Evolution & Development, 10 (4), 396-397 DOI: 10.1111/j.1525-142X.2008.00248.x