By 1910, the prescientific idea of the gonads as agents of sex differences had been transformed into the concept of sex hormones as chemical messengers of masculinity and femininity. With this conceptualization, sex endocrinologists reformulated the cultural notion of gonads as the seat of masculinity and femininity. Sex endocrinologists focussed their attention on the secretions of the gonads, rather than on the gonads themselves. In other respects, the scientific conceptualization of sex remained very close to common-sense opinions about masculinity and femininity. In the early period of sex endocrinology, the concept of sex hormones was straightforward and simple: there existed just two sex hormones, one per sex. In the period between 1905 and 1920, scientists defined sex hormones as exclusively sex specific in origin and function. With this conceptualiz-ation sex
endocrinologists suggested that sex had to be considered as a strictly dualistic concept.
This conceptualization not only harmonized with the prestientific idea of a sexual duality located in the gonads, but also found a ready acceptance given the cultural notions of masculinity and femininity of the day. In this period the dominant cultural idea of sex was determined by the Doctrine of the Two Sexes, a concept of sex developed in Victorian times but still prevalent in the opening decades of the twentieth century. According to this doctrine, women’s activities were in most respects the opposite of those of men. Therefore female and male were understood as opposite categories, not as two independent or complementary dimensions (Lewin 1984:169-170).
The idea of female and male as opposite categories was further reinforced by those sex endocrinologists who advocated the idea of sex antagonism. Some scientists—anticipating the women’s liberation movement at the turn of the century—had advocated the idea of sex antagonism. Among them was the British physiologist Walter Heape, who was the first to study the menstrual cycle of women in relation to the estrus cycle in animals. In 1913, Heape published a book entitled Sex Antagonism, an anthropological study claiming that women’s biological destiny was the opposite of men’s (Heape 1913). Heape refuted the claims of feminists to equal rights for women and argued that biology restricted women’s destiny to motherhood. Although it was criticized for its unfounded biological determinism, Heape’s colleagues subscribed to his view of the relations between the sexes. In his review of Sex Antagonism the British evolutionary biologist J. Arthur Thomson emphasized that it was good biology to emphasize that woman’s usefulness depends on her dissimilarity to man (Thomson 1914:346 as quoted in Long Hall 1975: 85).
In the 1910s, the Viennese gynecologist Eugen Steinach attributed the idea of sex antagonism to the concept of sex hormones. With Heape and scientists like the Dutch sexologist Van de Velde, Steinach shared a conservative reaffirmation of the traditional distinction between the sexes, emphasizing that the appropriate social roles for women were rooted in biology and opposite to men’s roles (Long Hall 1976). Steinach conceptualized the organism as a system of competing forces and persuaded his colleagues that male and female gonads secreted opposite, antagonistic hormones (Long Hall 1975:88).
In itself, the idea of sex antagonism was new to the field of sex hormones. Earlier workers like Brown-Sequard had restricted the function of sex hormones to stimulating the development of “homologous” sexual characteristics, suggesting that female sex hormones controlled female characteristics and male sex hormones male sexual characteristics. Steinach, however, attributed a double potentiality to sex hormones by suggesting that “sex hormones simultaneously stimulated homologous sexual characteristics and depressed heterologous sexual characteristics.” Besides stimulating the development of female sexual characteristics, female sex hormones were thought to suppress the development of male sexual characteristics.13
In more popular writings on sex hormones, this supposed antagonism between both type of hormones was compared with the relationship between men and women: “the chemical war between the male and the female hormones is, as it were, a chemical miniature of the well-known eternal war between men and women” (Kruif undated: 167). The conceptualization of sex hormones as antagonists thus fitted seamlessly with Victorian notions of the proper relationship between the sexes, and was consistent with the dualistic idea that each sex had its own specific sex hormone.
The emerging field of sex endocrinology shows a striking unanimity in interpretations of the concept of sex hormones. The groups involved in research on sex hormones, during this period mainly gynecologists and some biologists (physiologists, anatomists and zoologists), basically agreed about the conceptualization of sex hormones. This unanimity changed drastically when the field became more specialized and new groups entered the arena of hormonal research. In the 1920s, there emerged a lively dispute in the scientific community about the dualistic assumption that sex hormones are strictly sex-specific in origin and function. A growing number of publications appeared contradicting the prescientific idea of a sexual duality located in the gonads and underlying the original concept of the sexual specifity of sex hormones. The next sections describe how the different disciplines involved in the study of sex hormones gradually transformed the prescientific idea of sexual duality into a new meaning of sex.