Elizabeth A. Lloyd's new book, The Case of the Female Orgasm: Bias in the Science of Evolution, puts a stop to adaptationist tall tales. Lloyd's book is well worth your money, but you may also examine her argument and evidence in her conference paper "All About Eve: Bias in Evolutionary Explanations of Women’s Sexuality" (Proceedings of the Pittsburgh Workshop in History and Philosophy of Biology, Center for Philosophy of Science, University of Pittsburgh, 23-24 Mar. 2001), which excerpts from the book.
Lloyd's premise should be familiar to many fans of the late and lamented Stephen Jay Gould, who explained that the clitoris exists in a female body for the same reason that nipples exist in a male body: "Males and females are not separate entities, shaped independently by natural selection. Both sexes are variants upon a single ground plan, elaborated in later embryology" ("Male Nipples and Clitoral Ripples," Bully for Brontosaurus: Reflections in Natural History, NY: W.W. Norton & Co., 1991, p. 127). Lloyd writes: "It is crucial to note that the penis and the clitoris are the 'same' organ in men and women; there is an organ in the primordial, undifferentiated embryo that turns into a penis if it receives a dose of hormones, otherwise it matures into a clitoris. In other words, the penis and the clitoris have the same embryological origins and are thus called 'homologous' organs" (Lloyd, "All About Eve," p. 22). For those of us who are not committed to a baleful "principle of pervasive utility" (Gould, p. 126), the idea that "all parts of all creatures" must each play a useful function in evolution (Gould, p. 126), the story ends here. There is no mystery in female orgasm. Women can have orgasm because men can. The case closed. Or it should have been but wasn't.
Not only sexist scientists, for whom women are always full of mysteries, but many feminists also found "the thesis that female orgasm is an embryological byproduct of selection on the male orgasm" (Lloyd, p. 24) unpalatable, because they mistakenly assumed that such a thesis would make female orgasm derivative and therefore go against the ideal of female autonomy, so they, too, went in search of female orgasm's evolutionary utility independent of male orgasm's.
Far from making female orgasm a sign of female dependence upon men, however, Lloyd's history of female orgasm makes a powerful case for autonomy of female sexuality.
Based on primate research, Lloyd demonstrates that female orgasm among nonhuman primates is rare and that "the best evidence for female orgasm" in species among whom it is observed, such as stumptail macaques, "arose in homosexual mounts" during which the mounting female exhibited "all of the physical features of the orgasmic response in the males," rather than copulation during which the female didn't show any such features (emphasis added, Lloyd, pp. 26, 34). That being the case, the earliest human females, much like primates, must have discovered the joy of orgasm during masturbation or homosexual plays or both, rather than copulation -- unless the earliest human males were more solicitous of female pleasure than today's males, which is rather unlikely. Even today, Lloyd's review of sexological literature shows that "the numbers for orgasm all of the time with unassisted intercourse generally fall around the 15-35% range (Terman 1938; Chesser 1956; Tavris and Sadd 1977; Hite 1976; Fisher 1973), while the reported percentages of women who reliably have orgasm with intercourse, both assisted and unassisted, range from 38-53%" (Lloyd, p. 25).
Besides, contrary to those who wish to believe that female orgasm must have promoted "reproductive success," not only is there "little or no good evidence that differences in orgasm rate have any reproductive consequences at all" (Lloyd, p. 36); where there is evidence that points to reproductive consequences, all indications are that the less ability women had to control their own sexuality, let alone to insist upon enjoyment of female orgasm, the larger number of children they bore. Consider female genital cutting, which either diminishes or eliminates the capacity for female orgasm depending on types of cutting. You would expect that cut women have fewer children than uncut women, if female orgasm in any way led to "reproductive success," but such is not the case:
To date, no study has found an association between reproductive capability and FGC. While the Jones et al. study in Burkina Faso found that women who have been cut are more likely to experience obstetric complications, a 1998-1999 NHRC study found that women who were circumcised married earlier than uncircumcised women, and that circumcised women had greater total fertility than uncircumcised women (Reason 2004). Another study based on DHS surveys in the Central African Republic, Côte d’Ivoire, and Tanzania found that, when controlling for confounding socioeconomic, demographic and cultural variables, circumcised women, grouped by age at circumcision, did not have significantly different odds of infertility nor of childbearing than uncut women (emphasis added, Larsen and Yan, 2000). (Elizabeth F. Jackson, Philip B. Adongo, Ayaga A. Bawah, Ellie Feinglass, and James F. Phillips, "The Relationship between Female Genital Cutting and Fertility in Kassena-Nankana District of Northern Ghana," Paper presented at the Annual Meeting of the Population Association of America, Philadelphia, Pennsylvania, March 31-April 2, 2005, p. 4)If anything, patriarchal societies that diminish or eliminate women's capacity for orgasm, by genital cutting or any other means, appear to make women bear more children -- more "reproductively successful" -- than those that leave it intact.
In short, women discovered and have developed their capacity for orgasm on their own, for their own pleasure rather than reproduction, in spite of men who either have neglected it or sought to curtail or destroy it.