Grant: Discovery Grants Program - Individual

It has been said that reproduction is the engine that drives evolution. Nevertheless, non-conceptive sexual activity is widespread among humans and animals. At first glance, the existence of such behaviour seems to invalidate basic evolutionary theories, like sexual selection, which predict that behaviour evolves to facilitate reproduction. Why, then, do organisms engage in non-conceptive sex? This question represents one of the most outstanding paradoxes in psychology. The long-term goal of my research program is to understand why some species routinely engage in non-conceptive sexual behaviour and what the evolutionary consequences of such behaviour are for mating systems as a whole. To achieve this goal, I conduct cross-species and cross-cultural research on two primate species in which homosexual behaviour is frequently expressed. For the past 27 years, I have studied Japanese macaque populations in which both sexes regularly engage in homosexual and non-conceptive heterosexual behaviour, in addition to reproductive sex. I have also conducted human research in Samoa (since 2003) and in the Istmo region of Oaxaca, Mexico (since 2015), both cultures in which same-sex attracted transgender males are identified as non-binary genders: fa'afafine and muxes gunaa, respectively. Samoan fa'afafine and Istmo Zapotec muxe gunaa only engage in sexual activity with cisgender men, who, in turn, commonly engage in sexual activity with cisgender women as well. Significantly, my work demonstrates what other researchers have only recently come to formally acknowledge as biologically relevant; namely, that reproductive and non-conceptive sex develop and evolve in concert, and each can influence the other. By illuminating the dynamic interplay between reproductive and non-conceptive sex, my research furnishes transformative ways of thinking about the development and evolution of sexuality in humans and other animals. All too often discussions about sexual and gender diversity occur in an information vacuum that is driven by personal politics and morality, but divorced from any actual evidence. My proposed NSERC research program provides the psychobiological and evolutionary data relevant to many of the issues that are being currently debated among academics and the public. In doing so, my research helps to correct biased, erroneous, or incorrect views and provides a basis upon which an evidence-based, biologically relevant understanding of sexual and gender diversity can be situated. By actively disseminating my research results through scientific venues, as well as through the national and international media, I facilitate more intelligent and objective conversations about these topics. This, in turn, furnishes a foundation upon which evidence-based decision making related to sex and gender diversity can occur at all levels.