This used to be a popular topic but recently it seems to have died – of exhaustion perhaps? I remember the post-Kinsey glory days of Masters and Johnson versus Freud and the “clitoral versus vaginal” debate.Freud was in some ways the original “adaptationist” and for him the pleasure of female orgasm must serve some reproductive function hence it must come from vaginal penetration not just clitoral stimulation. (This was supported by the “G Spot” theory. Whatever happened to the G Spot?) For the sex therapy lobby it was about “normal orgasm” versus “orgasmic dysfunction” and they were not much into the adaptation debate; they just wanted bigger and better female orgasms wherever they came from. There was a whole industry of adaptationist arguments like Desmond Morris’s famous one that female orgasm evolved because it made women lie down after sex and thus helped the sperm speed on their way.This got its fair share of ridicule, but Morris produced some remarkable film (how he got it is its own remarkable story) showing that during orgasm the uterus actually tilted and scooped up sperm. As I used to point out to him he needed a control group of women who had sex but no orgasm to show that in their case the sperm didn’t get help and failed. I strongly doubted this happened. Sperm are terrific little swimmers – like salmon going upstream in the season. They don’t need help unless they are the neurotic version of Woody Allen.However, the Roman poet Lucretius in De Rerum Natura (Book 4) who was perhaps the original biologist to study this problem ,asked the question: “Why do whores move during intercourse while wives stay still?” He came to Morris’s conclusion that lying still would allow the sperm to travel up the tubes, but for him strenuous movement would prevent it. So for Lucretius all that movement during orgasm would be un-adaptive. He did say though that “pleasure was for both” and that “women’s passion is not always feigned.”Note that in the argument no one had any problem with the adaptive advantages of the male orgasm. It seems so obviously a pleasurable reward for sexual activity that it is taken for granted. The problem is the more elusive female version. It presents a paradox, for while it is much more difficult to achieve (on average) than the male, when it is “achieved” as they said, it is capable of giving repeated pleasure to the female in a manner denied to the male: the so-called “multiple orgasm.” Why, in any adaptationist argument, should this be? Why should not the female pleasure be as direct and immediately rewarding as the male?The whole debate was changed by Donald Symons in The Evolution of Sex (1979) who, in the face of the torrent of stories that “explained” the female orgasm as necessary to reproduction, claimed that it was in fact an evolutionary accident and had no adaptive functions at all. In the absence of female orgasms reproduction would still take place: all you need in an evolutionary sense is for the males and females to be motivated to copulate at all.Female mammals in estrus want to mate. After years of observing them do, so I can’t say I have ever seen a female mammal have a multiple orgasm or any kind of orgasm. In those societies of the world where orgasms are the rarest, the birth rate is the highest. In other words there is no evolutionary need for female orgasm at all. So why is it there, and why is it such a difficulty that a health industry exists to try to ensure that women can “achieve” it?Elizabeth Lloyd’s book The Case of the Female Orgasm in 2005 superbly documented the issue and demolished one by on the adaptationist arguments. Stephen J. Gould (“Freudian Slip” in Natural History, 1987) took up the cause and made this neat analogy: the female orgasm is like the male nipples. What are male nipples for? Answer, nothing. They are part of the package that comes at birth before the sex chromosomes kick in and decide the organism’s sexual future.The male is therefore left with nipples that serve no purpose, although they can give mild pleasure if simulated as gay males know. The same is true of the female clitoris. It is a female analogue of the male nipples. If the female can get pleasure from its stimulation, then this is a byproduct and has no function beyond the pleasure itself. As we have seen, the reproductive job gets done despite an enormous variation in the degree of female pleasure (from zero in those practicing female circumcision. to cultivated and elaborate as in the Kama Sutra).It is hard for a dedicated adaptationist to accept that something so intensely pleasurable cannot have a reproductive function. Melvin Konner (Why the Reckless Survive, 1990) made perhaps the most persuasive comeback in his argument based on differential male-female mating strategies. Males look to spread their sperm and so a “quick fix” orgasm suits them: get one; go for more.Females on the other hand have to be much more choosey about partners given their vastly greater investment, so they have evolved an orgasm that takes a longer time and needs a cooperative and considerate partner to achieve: the lover with the slow hand. It is part of the logic of sexual selection and female choice.In fact there has been an argument that the "real" function of female orgasim is to give females an advantage in collecting the sperm of an adulterous but well endowed lover! You can figure out for yourself why these do or do not work as an argument from what has gone before. Personally I find it hard to believe that female multiple ecstacies are an evolutionary necessity. So if they are not “for” anything, what are they?