The Evolution of Human Sexuality

Background

According to Symons, the ideas that he developed in The Evolution of Human Sexuality were partly inspired by a conversation he had with ethologist Richard Dawkins in 1968. Symons, who had concluded that "men tend to want a variety of sexual partners and women tend not to because this desire always was adaptive for ancestral males and never was adaptive for ancestral females", found that Dawkins had independently reached the same conclusion. Symons presented an early draft of his book during a 1974 seminar on primate and human sexuality he co-taught with anthropologist Donald Brown. Symons argued in the draft that there are universal human sex differences.

Brown assisted Symons in writing The Evolution of Human Sexuality.

Summary

Symons argued that women and men have different sexual natures, apparent in their typical "sexual behaviors, attitudes, and feelings", but partially concealed by moral injunctions and the compromises inherent in relations between the sexes. He attributed these differences to human evolutionary history, writing that during its hunting and gathering phase, the sexual desires and dispositions that were adaptive for men obstructed reproduction for women, while those that were adaptive for women obstructed reproduction for men. He wrote that his discussion of sex differences in sexuality is not intended to affect social policy. He discussed evolutionary concepts and the difficulties involved in applying them to humans, the capacity for orgasm, the loss of human estrus, sexual selection and its components intrasexual competition and sexual choice, the desire for sexual variety, and the development of human ovulation. He argued that among all peoples, sex is typically understood to be a service that females render to males.

In the introduction, Symons made what he considered six major points: that modern understandings of "natural selection" and "fitness" are value free, the latter term measuring reproductive success rather than referring to human value judgments, that is necessary to distinguish between proximate and ultimate explanations of animal behavior, the former being concerned with how animals come to develop behavior patterns, and the latter with why they develop these patterns, that while a feature of structure or behavior may benefit an animal, only features that result from natural selection should be considered functions, that the persistence of the nature-nurture controversy is partly the result of failing to distinguish between proximate and ultimate causation, that learning abilities are more often concerned with specific problems than they are the expression of general capacities, and that the secondary sex differences that exist in animals of most species are the consequences the different reproductive behaviors of males and females.

According to Symons, while orgasm in the human female has been proposed to be an adaptation resulting from selective forces, the available evidence, which shows that the female orgasm is far from being a universal result of heterosexual intercourse and that its frequency varies greatly between cultures and between individuals, does not support that conclusion. Symons suggested that the female orgasm may be possible for female mammals because it is adaptive for males. He noted that in most mammalian species the only known function of the clitoris is to generate sensation during copulation, but saw no evidence that "the female genitals of any mammalian species have been designed by natural selection for efficiency in orgasm production." He criticized Elizabeth Sherfey's view that the female orgasm is an adaptation, writing that her arguments are not supported by ethnographic or biological evidence. Symons proposed that male human ancestors lost the ability to detect ovulation in females by smell because females gained a reproductive advantage by concealing ovulation, and that estrus ceased to exist in humans at the same time. Observing that estrous female chimpanzees are more successful than nonestrous females in obtaining meat from males, Symons suggested that when hunting became a dominant male economic activity during human evolution, the benefits to females of receiving meat may have outweighed the costs to them of constant sexual activity, leading to women making sexual overtures to men in order to obtain meat.

In his discussion of "the desire for sexual variety", Symons reviewed literature on the "Coolidge effect", the "phenomenon of male rearousal by a new female". Discussing rape, Symons suggested that because males can "potentially sire offspring at almost no cost ... selection favors male attempts to copulate with fertile females whenever this potential can be realized." He criticized feminist Susan Brownmiller's book Against Our Will (1975) and her position that rape is not sexually motivated, writing that Brownmiller inadequately documents her thesis, more so than any major author since Konrad Lorenz in On Aggression (1963). He considered the major contribution of feminist investigations of rape to be to document the perspective of its victims, showing, for example, that they do not want to be raped. Symons argued that all of the reasons that Brownmiller and other authors have given for concluding that rapists are not motivated by sexual desire can be criticized. Responding to Brownmiller's claim that the function of rape is to keep all women in a state of fear, Symons observed that no process that might generate such "functions" has been shown to exist. Symons argued that socialization towards a "more humane sexuality" requires the inhibition of impulses that are part of human nature because they have proved adaptive over millions of years, and concluded that while under the right rearing conditions, "males could be produced who would want only the kinds of sexual interactions that women want" this "might well entail a cure worse than the disease."

Symons considered two different kinds of evidence especially important in supporting his claim that there are typical differences between the sexual desires and dispositions of men and women: hormone studies and the behavior of male and female homosexuals. Because homosexuals do not have to "compromise sexually with members of the opposite sex" their sex lives "should provide dramatic insight into male sexuality and female sexuality in their undiluted states." According to Symons, fundamental differences between men and women are apparent from the fact that, while there is a substantial industry producing pornography for male homosexuals, no pornography is produced for lesbians, and that lesbians, as compared to male homosexuals, have much greater interest in forming stable and monogamous relationships and having sex with loving partners.

He argued that the similarities between heterosexual and lesbian relationships, and the differences between both and the relations of male homosexuals, show that "the sexual proclivities of homosexual males are very rarely manifested in behavior." He proposed that heterosexual men would be as promiscuous as homosexual men tend to be if most women were interested in engaging in promiscuous heterosexual sex, and that it is women's lack of interest that prevents this. He considered, but rejected, alternative explanations for the differences between male homosexual and lesbian behavior, such as the effects of socialization, finding them unsupported. He concluded that while the "existence of large numbers of exclusive homosexuals in contemporary Western societies attests to the importance of social experience in determining the objects that humans sexually desire", the fact that male homosexual behavior in some ways resembles an exaggerated version of male heterosexual behavior, and lesbian behavior in some ways resembles an exaggerated version of female heterosexual behavior, indicates that other aspects of human sexuality are not affected by social influences to the same extent.

Mainstream media

Anthropologist Clifford Geertz reviewed The Evolution of Human Sexuality negatively in The New York Review of Books, writing that "virtually none" of Symons' claims are based on research Symons conducted himself, and that Symons "made no direct inquiries into human sexuality", instead basing himself on anthropological reports and other material, resulting in a book that is "a pastiche more than a study". Geertz accused Symons of supporting his views through selective use of evidence, such as an "extremely brief and fragmentary" review of the effects of hormones on human sexuality. Geertz considered Symons' characterizations of male and female homosexuals to be on the level of national or ethnic stereotypes, and found it questionable whether Symons' observations support his claims about differences between male and female sexuality. Geertz questioned whether Symons was correct to believe it possible to determine what natures and dispositions men and women have prior to the influence of human culture, and criticized Symons for viewing human sexuality as a biological fact with cultural implications rather than a cultural activity sustaining a biological process. Geertz disagreed with the favorable views of The Evolution of Human Sexuality expressed by biologists E. O. Wilson and George C. Williams, and the then president of the American Anthropological Association, calling the work impoverished. Geertz conceded that it might be the most important work on human sociobiology to date, but suggested that if true, this was unfortunate.

Scientific and academic journals

Anthropologist Sarah Blaffer Hrdy reviewed The Evolution of Human Sexuality positively in The Quarterly Review of Biology, crediting Symons with being one of the first to apply evolutionary theory to human sexuality and describing his work as "an insightful, theoretically sophisticated, and delightfully literate examination of the sexual emotions of men and women through the eyes of a sociobiologist." Hrdy predicted that many social scientists, but few few zoologists, would disagree with Symons' conclusion that there are innate psychological differences between men and women. Hrdy found Symons' review of biological literature on the "Coolidge effect", and the sociobiological literature on adultery, valuable, and although she found him to be "occasionally heavyhanded in extrapolating from the Coolidge effect to human philandering", considered his discussion of the relationship between nature and culture more sophisticated than that of most sociobiologists. Hrdy credited Symons with usefully drawing on both traditional anthropology and sociobiology. Finding his treatment of female sexuality is both more original and more controversial than his treatment of male sexuality, Hrdy noted that another observer might reach different conclusions on the basis of the same evidence, and argued that while Symons describes many aspects of female sexuality, including the female orgasm, as only accidental by-products of evolution, in her view they were selected for. Nevertheless, she called Symons' book "the best available study of human sexual emotions."

Psychologists Martin Daly and Margo Wilson reviewed The Evolution of Human Sexuality positively in The Sciences, writing that Symons brought an "even-handed, critical intelligence" to the discussion of the evolutionary basis of sex differences, and that he was willing to criticize the writings of sociobiologists where appropriate. However, Daly and Wilson found Symons' discussion of the evolution of concealment of ovulation in humans less useful than that of several other authors, including Hrdy, and they concluded that, though aware of the problems involved, he was not fully successful in establishing criteria to determine whether a given feature of an animal is an adaptation. They observed that though "seemingly bizarre", Symons' argument that the sexual behavior of homosexuals helps to test hypotheses about sex differences in sexuality is nevertheless logical.

Elmer S. Miller reviewed The Evolution of Human Sexuality in Social Science Quarterly, writing that it was well-written and fascinating, but that other scholars might interpret the data it relied upon differently, and that Symons did not fully answer questions about "the relevance of nonhuman animal studies for an understanding of human social life." Dean Lee argued in Biology and Philosophy that Symons' account of the female orgasm has been misunderstood in scholarly literature by Hrdy and others. According to Lee, while Symons' argument that the female orgasm has no adaptive value provoked controversy, little attention was given to the alternative explanation of the female orgasm Symons proposed, and Symons' actual view was not that attributed to him by his critics, who saw him as arguing that the female orgasm is possible because of the existence of the clitoris, which is itself a byproduct of the embryological connection with the male penis. Lee described the argument he ascribed to Symons as "obscure, complicated, and frankly speculative".

Evaluations in books, 1979–1992

Author Brian Easlea wrote that while Symons sees desire for anonymous sex as characteristic of men in general, it is actually typical only of sexist men. Easlea rejected Symons' view that socializing men to "want only the kinds of sexual interactions that women want...might well entail a cure worse than the disease". Feminist Susan Griffin described Symons' view that the female orgasm is not an adaptation but only a byproduct of selection for the male orgasm as an example of what she referred to as the ideology of the "pornographic mind", which conceives of female sexuality as "an empty space which craves male presence, and which cannot exist without the male."

Hrdy, writing in her book The Woman That Never Evolved (1981), asserted that, "Symons argues that women have sexual feelings for much the same reason that men have nipples: nature makes the two sexes as variations on the same basic model." According to Hrdy, it is because Symons holds this view that he maintains that female orgasms occur only as an accidental evolutionary byproduct of the existence of the adaptive male orgasm. Hrdy found Symons' view of female sexuality to be reminiscent of those of Aristotle and 19th century Victorianism. Biologists Richard Lewontin and Steven Rose, and psychologist Leon Kamin observed in Not in Our Genes (1984) that, like some other sociobiologists, Symons maintains that "the manifest trait is not itself coded by genes, but that a potential is coded and the trait only arises when the appropriate environmental cue is given." In their view, "Despite its superficial appearance of dependence on environment, this model is completely genetically determined, independent of the environment." They concluded that Symons' arguments provide examples "of how sociobiological theory can explain anything, no matter how contradictory, by a little mental gymnastics".

Biologist Anne Fausto-Sterling wrote that while Symons believes that rape should be eliminated, he also states in The Evolution of Human Sexuality that the rearing conditions needed to eliminate rape "might well entail a cure worse than the disease." Of that statement, Fausto-Sterling commented, "Worse for whom, one might wonder." Professor of Russian Daniel Rancour-Laferriere saw The Evolution of Human Sexuality as an "important treatise", but argued that while Symons questions whether the female orgasm is adaptive, the evidence Symons cites about animal behavior actually suggests that it is adaptive. Philosopher Michael Ruse, writing in Homosexuality: A Philosophical Inquiry (1988), concluded that while Symons' explanation of male homosexual promiscuity may possibly be correct, it depends on controversial and disputable claims.

Ethologist Irenäus Eibl-Eibesfeldt, discussing why there are no "visible signs of estrus in the human female", questioned Symons' argument that the absence of visible estrus in women developed so that they could "offer themselves to men to obtain portions of the booty from the hunt", pointing out that prey is shared in chimpanzees without sexual rewards. Eibl-Eibesfeldt rejected Symons' hypothesis that the female orgasm has no function because it occurs infrequently.

Author Jared Diamond, writing in The Third Chimpanzee (1991), called The Evolution of Human Sexuality "outstanding". Jurist Richard Posner called it the "best single book on the sociobiology of sex". Anthropologist Helen Fisher criticized Symons' views on homosexuality, writing that he wrongly believes that "homosexual behavior illustrates essential truths about male and female sexual natures". Psychologists Steven Pinker and Paul Bloom suggested that Symons' observation that "tribal chiefs are often both gifted orators and highly polygynous is a splendid prod to any imagination that cannot conceive of how linguistic skills could make a Darwinian difference."

Evaluations in books, 1993–2004

Journalist Matt Ridley, writing in The Red Queen: Sex and the Evolution of Human Nature (1993), argued that Symons' ideas about the evolution of gender differences had revolutionary implications, since "the overwhelming majority of the research that social scientists had done on human sexuality was infused with the assumption that there are no mental differences" between the sexes. Ridley endorsed Symons' explanation of male homosexual promiscuity. Psychologist David Buss called Symons' book "the most important treatise on the evolution of human sexuality in the twentieth century" and a "classic treatise". Journalist Robert Wright, writing in The Moral Animal (1994), called Symons' book "the first comprehensive anthropological survey of human sexual behavior from the new Darwinian perspective". He credited Symons with showing that the tendency for men to be more interested than women in having sex with multiple sexual partners holds good across many cultures and is not restricted to western society.

Philosopher Maxine Sheets-Johnstone observed that while The Evolution of Human Sexuality is "used as a textbook and is considered a major formulation of human sexuality", she sees as the work "a paradigm of the prevailing Western biological view" of female sexuality, a view she considers "essentially male".

Critic Joseph Carroll described Symons' book as "a standard work on the subject", but criticized Symons' arguments about homosexuality. Sociologist Tim Megarry dismissed it as, "a projection of American dating culture onto prehistory." Anthropologist Meredith Small argued that the work of sex researchers Masters and Johnson, which shows that the female clitoris is made of the same tissue as the penis and responds sexually in a similar manner, suggests that the clitoris results from an embryonic connection with the male penis and supports Symons' view that it is not an adaptation. Williams, writing in 1997, called Symons' book one of the classic works on "the biology of human sexual attitudes", alongside the work of anthropologist Hrdy. Author Alan F. Dixson described Symons' explanation of male homosexual promiscuity as "interesting".

Biologist Paul R. Ehrlich described The Evolution of Human Sexuality as a "classic but controversial treatise on human sexual evolution", and identified Symons' study of the development of human ovulation as a landmark. Biologist Randy Thornhill and anthropologist Craig T. Palmer, writing in A Natural History of Rape (2000), identified Symons as the first author to propose that rape is "a by-product of adaptations designed for attaining sexual access to consenting partners." They observed that Symons has falsely been accused of basing his arguments on the assumption that behavior is genetically determined, even though he explicitly rejects that assumption and criticizes it at length. Thornhill and Palmer endorsed Symons' explanation of male homosexual promiscuity, and his arguments against the idea that rape is not sexually motivated. Evolutionary biologist Stephen Jay Gould, writing in The Structure of Evolutionary Theory (2002), commented that the argument that the clitoris is not adaptive, put forward by Symons and subsequently by Gould himself, has been widely misunderstood as a denial of the adaptive value of the female orgasm in general, or even as a claim that female orgasms lack significance. Anthropologist Melvin Konner called The Evolution of Human Sexuality "the classic introduction to the evolutionary dimensions" of sex.

Pinker, writing in The Blank Slate (2002), called The Evolution of Human Sexuality "groundbreaking", and criticized what he considered personal abuse of Symons by Lewontin et al. in their discussion of Symons' book in Not in Our Genes.

Evaluations in books, 2005–present

Buss wrote that The Evolution of Human Sexuality was the first "watershed in the study of human mating strategies" to follow evolutionary biologist Robert Trivers' 1972 paper "Parental Investment and Sexual Selection" and a "trenchant classic". Buss credited Symons with being "the first to articulate the theoretical foundations of a fully adaptationist view of male and female mating minds" and "the first social scientist to take the writings of George C. Williams ... to heart, applying rigorous standards for invoking the critical but challenging concept adaptation." Buss described Symons' book as "the first major treatise on evolutionary psychology proper, highlighting the centrality of psychological mechanisms as adaptations and using human sexuality as a detailed vehicle for this more general argument." Author Elizabeth Lloyd concluded that Symons proposes "the best available explanation for the evolution of the female orgasm", stating that while Symons' conclusions are not beyond dispute, and have been criticized on a number of different grounds, they are consistent with existing evidence, and help to explain "otherwise mysterious findings."

Thornhill, writing with author Steven W. Gangestad, described The Evolution of Human Sexuality as "a landmark in the study of human sexuality" and "the first serious effort to investigate and inquire into the nature of human sexuality", adding that many of Symons' ideas have received support, including his view that women's sexuality includes "sexual adaptation that functions to gain access to nongenetic material benefits from males through its expression when women are not fertile within their menstrual cycles." Anthropologists Anne Bolin and Patricia Whelehan identified as Symons one of two major participants in the debate over the reproductive role of the female orgasm, the other being Sherfey. They wrote that Symons' view of female sexuality "reflects western concepts of the passive female and overlooks the evidence of actual female sexual functioning, such as the capacity for multiple orgasms in women." In their view, it is less likely that the female orgasm is a by-product of the male orgasm, as proposed by Symons, than that it is "an extension of the pleasurable sensations associated with coitus in primate females generally." They observed that while Lloyd endorsed Symons' view of the female orgasm, her work has been "severely criticized" by psychologist David P. Barash, and the relationship between female orgasm and reproduction remains a topic of ongoing debate.

Authors Christopher Ryan and Cacilda Jethá, writing in Sex at Dawn (2010), called The Evolution of Human Sexuality a "classic" work, but also accused Symons of having a "bleak" vision of human sexuality.