Frank Muscarella. Journal of Homosexuality. Volume 37, Issue 3. 1999.
Evolutionary psychology has captured the imaginations of both academics (e.g., Barkow, Cosmides, & Tooby, 1992) and the general public (e.g., Wright, 1994). The field examines human behavior in terms of its adaptive value, that is, its ability to contribute, either directly or indirectly, to survival and reproduction (Symons, 1992; Tooby & Cosmides, 1992). The model assumes that the brain may have evolved such that humans are predisposed to behave in particular ways because it was adaptive in the past (Tooby & Cosmides, 1992). The model also assumes that behavior that was adaptive in the evolutionary past may be discouraged in contemporary societies (Cosmides, Tooby, & Barkow, 1992; Fisher, 1992; Morris, 1967; Symons, 1979, 1992; Tooby & Cosmides, 1992), and local cultural forces may otherwise affect the manifestation of evolved behavioral dispositions (Tooby & Cosmides, 1992). Cross-species and cross-cultural data are used as evidence to support evolutionary hypotheses (e.g., Campbell, 1985; de Waal, 1982; Diamond, 1992; Fisher, 1992; Symons, 1979; van der Dennen, 1995).
The paradigm of evolutionary psychology has proven to be rich in heuristic value (Buss, Haselton, Shackelford, Bleske, & Wakefield, 1998). Human behavior running the gamut literally from love (in the form of mate selection) (Buss, 1989, 1992, 1994) to war (van der Dennen, 1995; Wrangham & Peterson, 1996) has been reevaluated in terms of its adaptive value during the course of human evolution. However, evolutionary psychology has failed to address homosexual behavior as it has addressed many other salient human behaviors. The consensus within the field of evolutionary psychology is that homosexual behavior does not have adaptive value and consequently did not evolve (Buss, 1994; Margulis & Sagan, 1991; McKnight, 1997; Posner, 1992; Ridley, 1993; Stevens & Price, 1996; Symons, 1979; Thiessen, 1996; Wright, 1994). However, some authors have argued that homosexual behavior is common among primates and may have been a trend in human evolution (Muscarella 1994, 1996, 1998; Vasey, 1995).
One factor which has undoubtedly contributed to the lack of evolutionary models of homosexual behavior is confusion over nomenclature. The problem of poorly operationalized terms is endemic to research in sexology in general (DiMauro, 1997), and is particularly acute in research on ‘‘homosexuality’’ (e.g., Shively, Jones, & DeCecco, 1984). This issue and a recommendation for clarifying it will be presented later. In this article, the term ‘‘homosexual behavior’’ is used to refer to any same-gender sexual behavior, irrespective of its motivation. The term ‘‘homosexuality’’ refers to the state of a predominantly same-gender sexual attraction and to the pattern of same-gender sexual behavior associated with it.
The remainder of this article will examine how both homosexual behavior and homosexuality have been treated in the field of evolutionary psychology and the factors that may account for this. Recommendations are made to help initiate alternative analyses of homosexual behavior from an evolutionary perspective.
The Role of Homosexual Behavior in the Evolutionary Model
Donald Symons’ (1979) book The Evolution of Human Sexuality was a seminal work which had a powerful impact on the study and understanding of human sexuality from the evolutionary perspective. It addresses the evolution of sexual behavior and gender differences. The book presents a now commonly accepted idea which has formed the basis of the contemporary study of mate selection (cf., Buss, 1989, 1992, 1994): males and females evolved different reproductive strategies.
Homosexual behavior is discussed frequently in the book, but there is no evolutionary explanation for homosexual behavior per se. Symons (1979) argues that the behavior of gay men and lesbians, unconstrained by traditional cultural guidelines, is evidence that there is a biological component to gender differences in human sexual behavior. In particular, the reported sexual promiscuity of gay men, and relative monogamy of lesbians is illuminated. This is done to support the hypothesis that, in general, males are sexually promiscuous while females are sexually discriminating and restrained. This theme becomes the leitmotif of the discussion of homosexual behavior in a number of future treatments of the topic.
The decade of the nineties ushered in a panoply of books which address, to various degrees, the evolution of human sexuality (e.g., Barkow et al., 1992; Betzig, 1997; Buss, 1994; Diamond, 1992; Fisher, 1992; Margulis & Sagan, 1991; McKnight, 1997; Ridley, 1993; Small, 1995; Stevens & Price 1996; Thiessen, 1996; van der Dennen, 1995; Vandermeer, 1996; Wrangham & Peterson, 1996; Wright, 1994). Four books among those reviewed here which devote considerable attention to human sexual behavior do not even include homosexual behavior in the index (Barkow et al., 1992; Diamond, 1992; van der Dennen, 1995; Wrangham & Peterson, 1996). Symons’ gay male promiscuity and lesbian relative monogamy argument is either the main or the exclusive treatment of homosexual behavior in five of the books reviewed (Buss, 1994; Margulis & Sagan, 1991; Ridley, 1993; Thiessen, 1996; Wright, 1994). In one of these books (Margulis & Sagan, 1991) the most elaborated indexed treatment of homosexual behavior is one sentence long and is a presentation of Symons’ argument. Only one book questions any aspect of Symons’ argument at all (Fisher, 1992).
Four of the books reviewed present homosexual behavior as something perverse and/or requiring special explanation. Stevens and Price (1996) reintroduce homosexual behavior as a ‘‘reproductive disorder’’ 23 years after the American Psychiatric Association decided to declassify homosexuality as a mental disorder. Human Nature: A Critical Reader (Betzig, 1997), through its title, implies an examination of human behaviors and their relation to the universality of human experience. In this light, the minimal treatment of homosexual behavior speaks volumes. The only indexed treatment of homosexual behavior is in relation to a description of the sexual licentiousness of several pathological Roman emperors. The inclusion of the material is presumably to underscore the point that males tend to be sexually promiscuous and are not selective in partner choice. Ridley (1993) relies heavily on the ‘‘gay gene’’ and prenatal hormone imbalance theories to explain homosexual behavior, which is implicitly considered to be biologically aberrant. One of the more compelling lines related to this is as follows: ‘‘Perhaps the gay gene is like those ‘male killer’ genes found in many insects. It effectively sterilizes males, causing the diversion of inherited wealth to female relatives’’ (p. 280). This ‘‘insect model’’ of male homosexuality moves from the incredible to the ironic when McKnight (1997) cites an argument by Ridley (1993) that ape behavior is not always an appropriate model for human heterosexual behavior because of evolutionary distance between species.
In The Moral Animal (Wright, 1994) homosexual behavior does not appear to fit within the paradigm that humans evolved a tendency toward a general moral nature. The physical placement of the largest single treatment of homosexuality appears to be a metaphor for its conceptualization here. The discussion is outside of the main body of the book in an appendix, titled ‘‘Frequently Asked Questions,’’ to which paradigmatic incongruencies are relegated. The section is described as a list of ‘‘puzzles and apparent puzzles that surround the new Darwinian paradigm as applied to the human mind’’ (p. 384). The first item on this list is subtitled ‘‘What about homosexuals?’’ The remainder of the section maintains that although homosexuality is not necessarily immoral, it is nearly impossible that it would have had adaptive value and evolved.
Two recent books examine the evolution of human male aggressiveness. The authors speculate that the human male tendency to build coalitions increased their access to females and ultimate reproductive success (van der Dennen, 1995; Wrangham & Peterson, 1996). The fact that neither book discusses homosexual behavior is particularly perplexing. Cross-species (Vasey, 1995; de Waal, 1982; Wrangham, 1976, cited in Crook, 1980), historical (Cantarella, 1992; Dover, 1978; Greenberg, 1988), and cross-cultural evidence (Blackwood, 1986; Greenberg, 1988; Herdt, 1997) suggest that, in the evolutionary history of human males, homosexual behavior played an important role in reinforcing alliances (Muscarella, 1994, 1998).
McKnight (1997) attempts to make an evolutionary analysis of homosexual behavior in humans and concludes that it is best explained as an evolutionary byproduct of the highly variable capacity of human sexuality. However, there are a number of difficulties with McKnight’s analysis. First, the byproduct explanation reflects the ‘‘spandrels’’ argument put forth by Gould and Lewontin (1979). This holds that some characteristics may not have been adaptations arising from natural selection but rather are the byproducts of the selection and evolution of other characteristics (e.g., behavioral plasticity). However, there has been a rigorous critique of the ‘‘spandrels’’ argument, particularly when applied to human evolution (Buss et al., 1998). Further, it is considered unlikely that important traits which are defining characteristics of a species (and homosexual behavior in humans has been described as such, e.g., Small, 1995; Wilson, 1978) have resulted from chance and are merely byproducts. Specifically, Tooby and Cosmides (1992) have stated that if the anti-adaptionist approach of Gould and Lewontin were correct, then no cross-individual uniformity would be imposed and humans would vary in important ways because of genetic differences.
Second, McKnight offers no analysis of cross-species patterns of primate behavior which is an important element of the evolutionary analysis of human behavior (de Waal, 1982, 1996; Diamond, 1992; Ridley, 1997; Symons, 1979; van der Dennen, 1995; Wrangham & Peterson, 1996). Third, Mcknight describes and then discounts the significance of a vast amount of cross-culturally manifested homosexual behavior because it is not associated with an exclusive homosexual orientation. For example, he states that there is significant evidence that many, if not most, adolescent males exhibit some homosexual behavior which stops in adulthood and is not associated with a homosexual orientation. The dismissal of the significance of this behavior at this stage is particularly perplexing. The evolutionary approach suggests that common behavior patterns in humans are often predictable and may have evolutionary significance (e.g., Tooby & Cosmides, 1992).
There are a number of published articles which address the evolution of homosexual behavior. The treatments of the topic are varied, but they almost all hold that homosexual behavior itself was not adaptive. Some theorists argue that homosexual attraction is biologically maladaptive because it reduces the likelihood of reproduction (Gallup, 1995; Gallup & Suarez, 1983). Archer (1996) considers this view to be ‘‘a welcome[d] change from earlier attempts to view homosexuality as possessing some hidden fitness-enhancing characteristic’’ (p. 276). Although homosexuality is seen to have no adaptive value, it is speculated that homophobia is adaptive (Gallup, 1995; Gallup & Suarez, 1983). According to these theorists, homophobia helps parents protect their children from seduction by homosexuals which would adversely affect their developing sexuality and ultimate reproductive success.
Other theorists argue, as does McKnight (1997), that homosexuality in humans is best conceptualized as a byproduct of the high degree of plasticity permitted by the human brain (Futuyma & Risch, 1984; Seaborg, 1984). Several other theories describe processes through which genes for homosexuality could have been passed on, despite a diminished likelihood of direct reproductive success, either through culturally mandated marriages for heirs (Weinrich, 1987), genetic polymorphism (Hutchinson as cited in Kirsch & Weinrich, 1991), or reproductively successful close relatives (Wilson, 1975, 1978).
The most frequently cited evolutionary theory of homosexuality is that proposed by E. O. Wilson (1975, 1978). This theory holds that during the course of human evolution homosexual individuals may have helped close family members, either directly or indirectly, to reproduce more successfully than they would have otherwise. Thus, genes for homosexual behavior would have been propagated indirectly by relatives. Although this theory was a watershed when it was first presented, there are a number of problems with it. Bancroft (1989) criticizes it broadly for being weak and insufficient, and no evidence has been found to support it (Buss, 1994; Wright, 1994). Greenberg (1988) argues that Wilson’s theory is based on untested assumptions about the distribution of resources in primitive, kin-ordered societies and upon the dubious assumption that homosexuality among primitives was restricted to a certain group of people who concomitantly avoided heterosexual contact. Small (1995) states that there is no evidence that homosexuality is associated with greater altruism.
An additional problem with Wilson’s theory involves cross-species comparisons. There is no evidence of a trend among nonhuman primates for increased altruistic behavior toward kin associated with increased homosexual behavior. In fact, homosexual behavior among nonhuman primates appears to increase the likelihood that the animals involved will provide assistance to their unrelated sexual partners (Akers & Conaway, 1979; Boelkins & Wilson, 1972; Parish, 1994; Small, 1992; Yamagiwa, 1987).
In spite of its almost total repudiation, Wilson’s theory has made its way into college-level introductory psychology texts as the primary model for the evolution of homosexual behavior in humans. This appears to be largely due to the lack of plausible alternative evolutionary models of homosexual behavior. Small (1995) reviews the topic of homosexuality thoroughly in her book on the evolution of human mating. With regard to models of homosexual behavior, she states that Wilson’s is ‘‘the only evolutionary one I know of’’ (p. 187).
In summary, of the sixteen contemporary books reviewed here which address the evolution of human sexuality, not one presents a model for the adaptive value of homosexual behavior in humans. Four of the books do not even include homosexual behavior in the index (Barkow et al., 1992; Diamond, 1992; van der Dennen, 1995; Wrangham & Peterson, 1996). In one book (Betzig, 1997), the only mention of homosexual behavior is that of sexually licentious and pathological Roman emperors used as evidence of lack of partner discrimination in males. Another book (Stevens & Price, 1996) reintroduces the concept of homosexual behavior as a disorder. In five of the books (Buss, 1994; Margulis & Sagan, 1991; Ridley, 1993; Symons, 1979; Thiessen, 1996), the focus of the discussion of homosexual behavior is on the promiscuity of gay men and sometimes on the monogamy of lesbians. Margulis and Sagan (1991) and Ridley (1993) take their material directly from Symons (1979). Thiessen (1996) draws primarily from Buss (1994) who relies primarily on Symons (1979). Symons’ work is thus the foundation for the treatment of homosexual behavior in a significant number of evolutionary analyses.
Why Homosexual Behavior Has Not Evolved
Three factors may explain the lack of models in evolutionary psychology which posit adaptive value for homosexual behavior: the dichotomous model of human sexuality, ambiguous definitions, and resistance to a paradigm shift.
The Dichotomous Model of Human Sexuality
Those writing in evolutionary psychology implicitly or explicitly maintain a more widely held cultural belief that human sexual orientation is dichotomous. That is, all humans can be neatly categorized as heterosexual and reproductive or homosexual and nonreproductive. The scientific search for the ‘‘gay gene’’ is guided by this conceptual position (Vandermeer, 1996). In essence, evolutionary psychology appears to maintain the position that homosexual behavior cannot be adaptive because it is not associated, even indirectly, with reproduction. For example, in The Moral Animal, Wright (1994) states, ‘‘One wouldn’t expect natural selection to create people who are disinclined to do the things (for example, heterosexual intercourse) that get their genes transported into the next generation’’ (p. 384).
A body of literature exists which strongly suggests that human sexual orientation is not dichotomous, but rather involves a complex admixture of heterosexual and homosexual interest, eroticism, and behavior (both overt and covert) (e.g., Adams, Wright, & Lohr, 1996; Ford & Beach, 1951; Gonsiorek & Weinrich, 1991; Herdt, 1981, 1984, 1988; Kinsey, Pomeroy, & Martin, 1948; Kinsey, Pomeroy, Martin, & Gebhard, 1953; Klein, Sepekoff, & Wolf, 1985; McConaghy, Buhrich, & Silove, 1994; McWhirter, Sanders, & Reinisch, 1990; Shively & DeCecco, 1977). Even the popular press has begun to address the greater variation of sexual expression among people. This variation is attributed partly to a rejection of the dichotomous categories ‘‘gay’’ and ‘‘straight’’ (Gideonse, 1997; Leland, 1995). Historical and cross-cultural research also support the contention that the simultaneous expression of heterosexual and homosexual behavior has been and is common for humans (e.g., Blackwood, 1986; Boswell, 1980; Ford & Beach, 1951; Greenberg, 1988; Herdt, 1997).
The dichotomous model of human sexuality gives rise to the curious dichotomization of homosexual behavior itself such that some is considered ‘‘real’’ and some not ‘‘real’’ or incidental. ‘‘Real’’ homosexual behavior tends to be associated with exclusive or near exclusive same-gender sexual partner choice. The emphasis of most evolutionary analyses of homosexual behavior is on what is implicitly or explicitly termed ‘‘real’’ homosexual behavior (e.g., Buss, 1994; Margulis & Sagan, 1991; McKnight, 1997; Posner, 1992; Ridley, 1993; Stevens & Price, 1996; Thiessen, 1996; Wright, 1994). These analyses tend to dismiss the evolutionary importance of homosexual behavior attributed to any cause which is considered incidental: play (adolescent or adult), exploration, lack of opposite-gender partners, hazing, initiation rituals, intoxication, sexual frustration, prostitution, boredom, opportunism, curiosity, and mistakes. Ironically, some authors go to great lengths to describe the vast amount of homosexual behavior considered not ‘‘real’’ homosexual behavior to make the point that exclusive homosexual behavior is rare (e.g., McKnight, 1997; Posner, 1992). The dismissal of homosexual behavior not associated with a predominantly homosexual orientation may be causing theorists to miss an important and evolutionarily significant behavior pattern in human sexuality.
Ambiguous Definitions
A second factor which may have impeded the study of the evolution of homosexual behavior is a problem of definitions (Greenberg, 1988; Herdt, 1997; Vandermeer, 1996). There is a lack of clear definitions for the terms sexual orientation, homosexual behavior, homosexuality, heterosexuality, lesbian, gay, straight, and bisexual–both within our own culture and across cultures. Consequently, it is often difficult for the reader to know specifically what phenomenon is under evaluation and discussion in any given report. Shively et al. (1984) analyzed the conceptual and operational definitions of sexual orientation in 228 articles from 47 different scientific journals. They suggested that the great variation found in these definitions reflects general underlying conceptual confusion. Gonsiorek and Weinrich (1991) have also noted that the confusion surrounding the concept of sexual orientation reflects a lack of basic construct validity.
Resistance to a Paradigm Shift
The third factor which seems to contribute to the lack of theorizing about the adaptive value of homosexual behavior is resistance to a paradigm shift. The resistance to paradigm shifts in science which require new attitudes or which conflict with strongly held beliefs is not new (Kuhn, 1970). The issue of a paradigm shift in evolutionary theory was addressed over 17 years ago by Sarah Blaffer Hrdy (1981), whose book inspired the title for this article: The Woman That Never Evolved. Hrdy pointed out that the strong and traditionally androcentric view of the world in primatology, anthropology, and evolutionary biology had led to a then commonly accepted theory of evolution in which females had almost no role. Explicitly or implicitly stated, most evolutionary change was seen to have been brought about through males.
Likewise, contemporary Western cultures have a historically and profoundly negative view of homosexuality (Boswell, 1980; Tannahill, 1982). This has adversely affected its study in many disciplines (Herdt, 1997; Ricketts, 1984; Vasey, 1995; Weinrich, 1980, 1987) and continues to do so at even the most prestigious universities (Arenson, 1997). The research of scientists is embedded within their own personal views and values whether or not these are made explicit (Kuhn, 1970). An acknowledgement that homosexual behavior has had adaptive value would require theorists to abandon deeply entrenched and often unrecognized stereotypes. The concepts of a dichotomous sexual orientation and a ‘‘gay gene’’ would also have to be reexamined. Furthermore, theorists would be required to see the potential for homosexual behavior, at least under environmental conditions similar to those in which it may have evolved, in all humans.
Recommendations
Four recommendations are offered to help evolutionary psychology develop alternative models for the conceptualization of homosexual behavior. First, breaking with the traditional study of homosexual behavior in evolutionary psychology, the focus of study should be homosexual behavior per se, irrespective of sexual orientation. Related to this, it would be useful to stop using ambiguous and unreliable terms like ‘‘homosexuality’’ and ‘‘gay’’ in scientific writing about the evolution of same-gender sexual behavior. Herdt (1997), addressing this issue, suggests the neutral descriptor ‘‘same-gender sexual relations.’’ The term ‘‘homoerotic’’ has also been suggested (Muscarella, 1994). In its most conservative definition, it might mean same-gender sexual behavior involving genital contact that appears to be sexually pleasurable.
Obviously, homoerotic behavior would be an important component of the psychological phenomenon which leads some individuals to label themselves lesbian, gay or bisexual. However, sexual orientation is a complex construct whose definition lacks consensus among those who research it (Gonsiorek & Weinrich, 1991; Greenberg, 1988; Herdt, 1997; Shively et al., 1984) despite continued efforts to explain its development (Bem, 1996; Money, 1986). Homoerotic behavior can be conceptualized as a component of sexual orientation and incorporated into theories of its development. However, the term homoerotic allows instances of same-gender sexual behavior exhibited by humans who do not consider themselves homosexual or bisexual to be equally erotic and biologically and psychologically meaningful. The operational definition presented allows same-gender sexual behavior to be more readily identified across temporal, cultural, and political zones. This, in turn, will substantially increase estimates of its incidence as well as provide support for its universality in humans. Consequently, implications of adaptive value arise, and an understanding of the behavior’s evolutionary history may become more compelling.
Second, colleagues in primatology and comparative psychology should be urged to document rather than ignore homoerotic behavior in nonhuman primates and theorize about its adaptive value. It has been suggested that homoerotic behavior among nonhuman primates reinforces relationships which may contribute to individual survival and ultimate reproductive success (Akers & Conaway, 1979; Boelkins & Wilson, 1972; Ford & Beach, 1951; Small, 1992; Vasey, 1995; Wrangham, 1976, cited in Crook, 1980; Yamagiwa, 1987). However, this hypothesis has not been carefully and systematically studied (Vasey, 1995; Weinrich, 1980).
Weinrich (1980) has noted that strongly negative attitudes toward homosexual behavior have affected biological research. Homosexual behavior observed among infrahuman animals has sometimes been attributed to ‘‘stupidity’’ on the part of the animals or has been interpreted as ‘‘not really’’ homosexual behavior. Most often the antihomosexual attitudes have caused homosexual behavior to be ignored or dismissed. Fifteen years later, Vasey (1995) stated that despite the prevalence of homosexual behavior among nonhuman primates and its long evolutionary history, no satisfactory theoretical frameworks exist for its interpretation. Further, he states that virtually every major introductory text in primatology fails even to mention homosexual behavior, giving the impression that it is rare or nonexistent.
Third, colleagues in cultural anthropology should be urged to increase their study of homoerotic behavior and theorize more often about its socially positive and biologically adaptive qualities. There has been strong criticism of the anthropological study of homosexuality in the past, which has been viewed as uninspired, biased, and plagued with theoretical and methodological problems (Blackwood, 1986; Greenberg, 1988; Herdt, 1988, 1997; Williams, 1986). Herdt (1997) reports that the anthropological study of homosexual behavior has been largely taboo until very recently.
Fourth, evolutionary psychologists should be urged to consider homoerotic behavior in all treatments of ‘‘human sexuality.’’ Further, they should apply the same careful evolutionary analysis to homoerotic behavior that is applied to other human behaviors. A number of criteria would help guide the development of evolutionary models of homoerotic behavior in humans:
- A theory should take into account similar same-gender sexual behavior across cultures and historical periods rather than rely upon contemporary culture-bound definitions of ‘‘homosexuality.’’ Definitions vary widely. Scientific models based upon definitions which lack reliability have commensurately diminished validity and usefulness. Furthermore, Eibl-Eibesfeldt (1990) has noted that there are many expressions of homoerotic behavior which may suggest a variety of evolutionary origins. Future theorizing and research may be improved by identifying and explaining reliable patterns of homoerotic behavior in humans rather than attempting to explain all manifestations of homoerotic behavior with one theory.
- A genetic element to the disposition to engage in homoerotic behavior must be assumed. Most major theorists agree that human sexual behavior in general is biologically influenced, presupposing some genetic element (Bancroft, 1989; Greenberg, 1988; Small, 1995; Symons, 1979; Wilson, 1975). Furthermore, there is mounting evidence of a genetic role in the development of a primarily homosexual orientation in some individuals (Bailey & Pillard, 1991; Hamer & Copeland, 1994; Hamer et al., 1993; LeVay, 1993). However, genetically influenced characteristics vary among individuals and interact with the environment, which contributes to individual differences in their expression (Barash, 1982; Lewontin, 1982; Vandermeer, 1996).
- A theory should show the existence of homoerotic behavior and its adaptive qualities in other species of primates, particularly the great apes. The great apes share a high degree of genetic relatedness to humans (Cherfas & Gribbin, 1981). Thus, it is believed that their sociosexual behavior may provide especially important insights into the evolutionary origins and functions of human sexual behavior (Graham, 1981). Cross-species comparisons are requisite in the evolutionary study of most behaviors (de Waal, 1982, 1996; Diamond, 1992; Wrangham & Peterson, 1996).
- Based upon cross-species and cross-cultural evidence, a theory should make some reasonable conjectures about the role of the behavior and the forces which may have impinged upon its selection during human evolution. Specifically, a theory should describe how homoerotic behavior may have solved an adaptive problem for human ancestors (cf., Buss et al., 1998; Tooby & Cosmides, 1992). That is, the adaptive value of homoerotic behavior during the course of human evolution must be indicated and related to reproductive success, which is the ultimate measure of adaptiveness. Symons (1992) states that human behavior can be expected to be adaptive: consequently, it can be analyzed in terms of its reproductive value. Similarly, Tooby and Devore (1987) have stated that many of the characteristics displayed by humans were selected because they were adaptive.
There are two important caveats here. One, it is assumed that the contemporary dichotomous view of human sexuality is rejected. Thus, for most humans throughout most of the species’ history, a disposition to engage in homoerotic behavior would not have precluded heteroerotic behavior and consequent reproduction. Two, behavioral predispositions which were useful and adaptive for hominids and early humans may be discouraged or prohibited in contemporary cultures (Tooby & Cosmides, 1992). Evolutionary explanation focuses on why a behavior exists not its contemporary advantages or disadvantages (Buss et al., 1998).
Addressing the criteria above, I have presented an alternative model of the evolution of homoerotic behavior in humans (Muscarella, 1994, 1998). It posits that hominid adolescents and young adults may have gone through a period of gender-segregated social and physical peripheralization similar to that found among many primates. Homoerotic behavior may have served as a mechanism of affiliation which reinforced and strengthened the relationships between same-gender peripheralized hominids themselves and with higher status conspecifics. Allies may have increased the likelihood of individuals obtaining access to resources, obtaining mates, and successfully raising offspring. Thus, homoerotic behavior may have indirectly contributed to survival and reproduction.
Conclusion
In summary, evolutionary psychology has proven to be of great heuristic value and has challenged and expanded our understanding of many human behaviors. Lamentably, homoerotic behavior is an exception. As a result, our understanding of homoerotic behavior stagnates as our understanding of other behaviors advances. Cosmides et al. (1992) have indicated that an examination of psychological mechanisms (e.g., homoeroticism) can be used to investigate the possibilities of adaptive function. Thus, theorists in evolutionary psychology are urged to use contemporary research on human sexuality, cross-species behavior, and cross-cultural and historical behavior to formulate answers to the question: ‘‘How might homoerotic behavior have been adaptive during the course of human evolution?’’