The use of sex hormones to explain, refer to, or delimit sexual differences is, terminologically at least, specific to the twentieth century: the word ‘hormone’ was coined in Britain in 1905. The concept of chemical messengers of sex, however, is somewhat older than this. This chapter describes the development of this concept and shows how nineteenth- and early twentieth-century scientific theories about sex hormones were transmuted into strong claims about the determinative role of these chemicals in producing a broad range of physical, behavioural and psychological sexual differences in humans and other animals. This process involved the elision of more nuanced and less biologically determinist understandings of hormones as actors in producing sex. Through critically retelling a history of the hormonally sexed body, this chapter begins to investigate and elaborate both mainstream and alternative technoscientific figurations of hormones and to contribute to creating a ‘history of bodies’ in the Foucauldian sense, exploring what it might mean to think about bodies and ‘the manner in which what is most material and most vital in them has been invested’ (Foucault 1987: 152).

Histories of sexual differences

It has been claimed by historians of science, and most notably by Dutch science-studies theorist Nelly Oudshoorn (1994), that the ‘discovery’ or production of hormones in the early twentieth century marked a highly significant change in understandings of the nature of sexual difference.