OK, then how do you explain societies in which ALL women report orgasms (such as Mangaians and a few other Polynesian islanders among whom female sexual pleasure is taught to both boys and girls) AND societies in which it is entirely unknown. Population genetics?
We may have little evidence (other than logic) that female orgasm is a direct adaptation, but that's different from saying it's not a universal female possibility. Someone (Donald Symonds?) gives the analogy, we're not adapted to write or read, either, but nearly any human is equipped to do so.
Also, if you asked our oddly frigid twin sample if they get physical pleasure from sex (ignoring orgasm for a moment) I think you'll find the numbers higher. Would that mean female sexual pleasure is an adaptation but the particular category of it, female orgasm, isn't?
Jenny Brown