Miles Jackson
Well, you conveniently ignored some data that contradicts your argument! Female orgasms are far more likely to occur from masturbation than intercourse. If female orgasm is an adaptation to encourage intercourse,shouldn't it be the other way round?
^^^^^ CB: Well, no , not necessarily. Ability to have orgasms from masturbation might just be one of your favorites: a spandrel-like trait in relation to the orgasms that accompany intercourse. Modern women ( people) having more orgasms from masturbation than intercourse doesn't mean that the masturbation was not originally the spandrel-like trait.
That vocal chords are used more for talking than anything else doesn't mean that talking isn't the spandrel to some other functionally adaptive use of the vocal chords.
How exactly do you suppose increased masturbation increases fitness ? That's what a spandrel-like trait would be. Something that in itself has no adaptive value, but which is a side effect of something that is adaptive. Orgasm in masturbation is the better candidate for spandrel-like quality than the orgasm during intercourse, because increased intercourse increases fertility and increased masturbation does not do so as directly.
Again the main point is that anything that directly increases heterosexual intercourse is extraordinarily likely to increase fitness via differential fertility, more likely than all other traits, all of which basically increase fitness by _in_directly increasing fertility.
Isn't masturbation a spandrel-like trait with respect to fertilizing function of the penis ? What do you want to bet that men have orgasms a higher percentage of the time masturbating than in intercourse ? Would you say the ability to have penis-orgasm in intercourse is a spandrel-like trait in relation to penis-masturbation? No.
^^^^
> CB: Spandrel of what ? A spandrel has to be the side effect of another
trait
> that is selected directly.
Pick anything. Could be a contingent, genomic link with any other gene clusters. There doesn't need to be any meaningful or functional link between the trait selected via evolution and another trait that comes along "for the ride".
Here's one plausible story: in males, the structure of the penis is a product of natural selection (intercourse is a highly effective way of encouraging reproductive behaviors in males). The clitoris is anatomically analogous to the penis, there was no direct adaptive pressure to eliminate this analogous structure in females, so it persisted.
Miles ^^^^^^
CB: Yes, that's what the article Yoshie referenced ("Female Orgasms and Evolutionary Theory) seems to say: The clitoris is a spandrel-like trait in relation to the penis. Or the clitoral orgasm is a spandrel-like trait in relation to the penis-orgasm, since the penis is a clitoris at a certain stage of the development of the fetus. So, we finally have you saying some trait is adaptive. The penis orgasm _is_ the product of natural selection. Thank Darwin.
My thought in response was why wouldn't both the clitoris and the penis be selected for ? Or ,afterall, since the original, fetal organ that both males and females have is the clitoris, not the penis, why not speculate that the penis is spandrel-like trait to the clitoris, which was the trait naturally selected for ?
Why bend over backwards to look for a way to find that the clitoris and vaginal orgasm are not adaptive traits ?