["If Hormones Make the Man, What Makes the Woman?" : The Beginnings of Endocrinological Sex Development Research...

While the genetically and hormonally controlled prenatal development of male genital organs has been described in increasing detail since the beginning of the 20th century, and several genes involved in ovarian development have now been identified, the hormonal factors involved in female genital differentiation remain largely unexplored to the present day. The physiological model that continues to prevail today follows a binary logic of the presence and absence of hormonal and genetic factors: masculinity appears as the result of active biological processes, while femininity appears as their absence and passive "default pathway". Historically, this model can be traced back primarily to the animal experiments conducted by the French embryologist and endocrinologist Alfred Jost in the 1940s. Feminist criticism of science, some of which comes from the life sciences themselves, has for several decades been problematising the continuing dichotomy of activity and passivity as a reproduction of traditional cultural assumptions about gender, as well as the desideratum of researching prenatal female sex differentiation, which in their view requires explanation. This article takes up this longstanding critique and expands on it with a historical analysis of the material and technical conditions of early embryonic sex development research in the first half of the 20th century. Based on four central experimental systems-(1) the anatomical and morphological studies of Pol Bouin and Paul Ancel around 1900, (2) research on Freemartinism in the 1910s, (3) Eugen Steinach's sex reversal experiments in the 1910s, and (4) Vera Dantschakoff's embryological sex hormone research in the 1930s-it is shown how the binary, masculinity-focused model of embryonic sex development was already taking shape before the 1940s under the influence of specific material and technical research conditions of the early endocrinological experimental systems. The aim is to highlight the role of these material and technical conditions, and in particular of hormones as epistemic, technical and sometimes rebellious things within these systems, and to discuss possible path dependencies up to current experimental configurations in sex development research.