The Genetic Inactivation of the Vomero-Nasal Organ in Primates Allows the Evolution of Same-Sex Sexual Behavior But Does Not Explain Homosexual Orientation in Humans

A variety of mammals, including primates, communicate through pheromones, which are volatile chemical signals produced by glands and detected through the vomero-nasal organ (VNO). This manner of communication is efective and fundamental for eliciting innate responses to locate sexual partners and inducing sexual behavior. Pfau, Jordan, and Breedlove, (2019) hypothesized that progressive degeneration of a single-gene coding for pheromones receptors in the VNO of mammals may have triggered a cascade of functional and behavioral consequences that facilitated the development of new modes of sexual communication, including same-sex sexual behavior in primates and humans. This hypothesis is compelling, testable, and heuristic.