Further Insights

The evolutionary framework developed in this book can also enable us to understand a range of additional phenomena related to mating. In the paragraphs that follow, I will examine briefly same-sex attractions, rape, and sports.

Same-Sex Attractions

Attraction to the opposite sex is a mechanism that enables individuals to address all reproductive niches: It motivates people to appeal to parents so as to gain reproductive access to their offspring, to fight other men and monopolize access to women, to pursue mates and persuade them to establish an intimate relationship with them, and to force sex to women. Given that this mechanism enables individual to address all niches, we would expect that almost all individuals experience heterosexual orientation. This prediction is partially confirmed: About 90% of individuals classify themselves as being attracted predominantly to opposite sex partners (heterosexual) (LeVay, 2010). However, a small percentage of individuals classify themselves as being attracted to both sexes (bisexual) and as being attracted mainly to the same sex (homosexual) (LeVay, 2010; Savin-Williams, Joyner, & Rieger, 2012). Furthermore, a considerable proportion of individuals experience varying degrees of same- sex attraction, although they have a heterosexual orientation (Calzo, Masyn, Austin, Jun, & Corliss, 2016; LeVay, 2010). These observations lead to the question why selection forces have not eliminated any dispositions for same-sex attraction from the population.

One possibility is that same-sex attractions have little consequences in addressing the parental choice niche, especially for women (Apostolou, 2016d). For instance, women are given by their parents in marriage to men, who can force sex to them at will (Apostolou, 2014). Thus, whether a woman experiences same-sex attractions or not is inconsequential for her reproductive success. In different words, selection pressures in ancestral human societies, where mate choice was regulated, had been weak on alleles that predispose for same-sex attractions, resulting in them to be in a relative high frequency in contemporary populations.

Another, not mutually exclusive, possibility is that same-sex attractions enable individuals, particularly women, to better address the individual mate choice niche (Apostolou, 2016e). In more detail, men face the problem of parental uncertainty; thus, if their partners experience same-sex attractions, they will divert part of their mating effort to same-sex outlets which reduces the chances of cuckoldry. Accordingly, men find the same-sex attractions of their partners desirable, which means that women who experience such attractions may better address the individual mate choice niche, i.e., by being more likely to keep a partner than women who do not experience such attractions.

I have also argued that homosexual orientation in men can be fitness-increasing if certain conditions are met, i.e., if they live in an agropastoral mate context and have several older brothers. In such a context, inheritance rules favor the firstborn sons (Apostolou, 2013a). Latter-born sons are usually left with little wealth to inherit, which compromises their chance to establish a good marriage. As a consequence, conflict is likely to arise between brothers for access to their family’s resources. A homosexual younger brother will not have such conflict, which increases his inclusive fitness, while he can still be given to marriage by his parents and procreate, even if the marriage deal is not that good. In this respect, male same- sex orientation may have started increasing in prevalence following the agropastoral revolution (Apostolou, 2013a).

Note that the above arguments are not mutually exclusive. Strong parental choice reduces the fitness costs of same-sex attraction, while the reduction in paternal uncertainty and the reduction in conflict within the family increase its fitness benefits.

The puzzle of same-sex attraction has not yet been resolved, but the theoretical perspective developed in this book can provide several useful insights that can contribute to its solution.

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