The Origins of Gender, not Sex: Evolution and the Reproductive Axis

• This study presents what and where a biological gender resides in the human phenotype, giving further provenance to identity development and diversity separate from body sex. • Evolutionary principles, including natural and sexual selection, drive the evolution of traits that enhance survival and reproduction, leading to the prevalence of certain behaviors and psychological dispositions in males and females. These differences are adaptive for the human species as a whole and are regulated and maintained by evolutionary pressures. • Several stable and dimorphic cognitive behaviors influenced by innate sex hormones and regulated by reproductive drives play a role in the development of gender identity. • These gender differences in cognitive behavior are not solely a result of socialization. • Given the biological component of gender, what are the potential implications of studying cis- and non-cisgender communities? What are the current limitations and challenges to understanding the genetic basis of transgenderism?