Response to Commentaries: Transgenerational Same-Sex Sexual Behavior, Typology, and Etiology

In their commentaries, Muscarella (this issue) and Greenberg (this issue) added support and detail to my argument that male transgenerational and androphilic same-sex sexual behavior need to be studied separately in evolutionary analyses, which necessarily entails matching evolutionary-related evidence with corresponding same-sex sexual type. In Muscarella’s (this issue) view, evolutionary adaptive explanations regarding the transgenerational form are indeed appropriate, given that such explanations (i.e., those based on male–male cooperation and the mechanisms supporting this) are consistent with commonly accepted scenarios of early humans and the environmental demands they faced. By contrast, he continued, the adaptive functioning of the transgender (i.e., androphilic) form has not been established, and this form may be better understood as “noise” (i.e., evolved, but not as an adaptation or byproduct of an adaptation). Greenberg (this issue) emphasized the importance of employing typology (e.g., transgenerational, transgenderal) in evolutionary explanations. He noted that the different types of human same-sex sexual behavior may have arisen at different points in time for different selective reasons, and so failure to acknowledge typology can lead researchers astray in theorizing and empirical testing. In terms of origins of the transgenerational form, Greenberg argued that it is likely a conserved trait, given its widespread occurrence across species (though he opined that the bonding aspect found in humans may be peculiar to their evolutionary history). In this reply, I supplement some of Muscarella’s (this issue) and Greenberg’s (this issue) key points by briefly considering male transgenerational same-sex sexual behavior in primates, with a focus on Japanese macaques. Then I briefly consider some of Riegel’s (this issue) comments. In several recent authoritative reviews of primate same-sex sexual behavior, Dixson (2010, 2012) maintained that attempts to validly understand human same-sex sexual behavior require a thorough analysis of same-sex sexual behavior in other primates. From his analyses, he concluded that same-sex sexual behavior in the Cercopithecoidea (i.e., Old World monkeys) and Hominoidea (i.e., apes and humans) is a conserved trait, likely present in common ancestors of these superfamilies and passed down over evolutionary time to descendent species, including modern humans. Within these superfamilies, he noted, same-sex sexual behavior is particularly characteristic of immature males. He documented that this includes human immature males, drawing from the Kinsey data and the anthropological record. In Old World monkeys, apes, and humans alike, Dixson (2010) noted, same-sex sexual behavior among males is generally part of a bisexual pattern, with considerable potential, and the same-sex sexual aspect not infrequently appears in the transgenerational form (see Vasey, 1995, for documentation). By contrast, he noted, there is no analog in other primates to the exclusive androphilic form of male samesex sexual behavior that occurs in humans. Thus, although the transgenerational form in