Abstract

This study situates Henry Havelock Ellis’s sexological research within the nineteenth-century evolutionary debates, especially the discussion over sexual selection’s applicability to humanity. For example, Ellis’s monograph on sexual behavior, _Sexual Inversion_ (1897), treated inborn homosexuality as a natural variation of evolutionary mechanisms. This book was situated within a longer study of human sexuality in relation to evolutionary selection. His later works dealt even more directly with Charles Darwin’s concept of selection, such as _Sexual Selection in Man_ (1905). Through _Sexual Selection in Man_, Ellis asserted that sexual attraction stemmed from a physical cause rather than an innate aesthetic sense. I argue that Ellis’s best-known historical publications, including his work on sexual inversion, were intended to intervene in the contemporary evolutionary debates. This analysis also identifies a specific point where evolutionary theory informed the foundation of sexology as a scientific discipline.