The dispute over the sexual specificity of sex hormones did not only address the origin of sex hormones. In the 1920s, the function of “hetero-sexual” hormones was also frequently discussed. If female sex hormones were present in males, should the concept of an exclusively sex-specific function of sex hormones then be reconsidered as well? Scientists questioned whether female sex hormones had any function in the development of male organisms and vice versa. This section analyzes the positions the different disciplines involved in the study of sex hormones took in the debate about the sex — specific function of sex hormones.
The debate about the sex-specific function of sex hormones developed along lines similar to the discussion about the origin of sex hormones. Initially, scientists adhered to the prescientific notion of sexual duality. This assumption made it difficult to conceive of any function for hetero-sexual hormones at all, and therefore different hypotheses were proposed suggesting a functionless presence of the hormones. In 1929, the Amsterdam School suggested that female sex hormones probably had no function in the male body, because the concentration of female sex hormone in males was too small (Jongh et al. 1929:772); in this period the amount of female sex hormone was thought to be considerably less in males than in females.
The assumption that female sex hormones had no function in male bodies directed research throughout the 1920s. In 1934, the Amsterdam School described how in 1928 they had observed the growth of the seminal vesicles in castrated rats after treatment with female sex hormones, but they had simply overlooked this function of female sex hormone in male animals. They described this observation as follows:
Menformon (female sex hormone)—also the completely pure preparation—enlarges the seminal vesicles of animals castrated when they were young. Although this enlargement does not develop into the adult size of the seminal vesicles, this enlargement is beyond dispute. We had observed this enlargement already for years. However, we had neglected this observation because we thought it fell within the margin of error. Freud20 and de Jongh made this observation in several different experiments. Also outside our laboratory [here the authors referred to the German scientist Loewe] the same observation was made, but was attributed to the presence of small amounts of male sex hormones in the ovarian extracts. From histological analysis I learned (and I had the pleasure of convincing Professor Loewe during a visit to our laboratory) that this conception is not right. Female sex hormone does enlarge the seminal vesicle, but in its own specific way. Male sex hormones stimulate the growth of epithelial parts and female sex hormones stimulate the growth of non-epithelial parts of the seminal vesicles.
(Jongh 1934b:1,209)
The concept of sexual specificity also structured the debate about the function of “heterosexual” hormones in human bodies. Clinicians suggested that female sex hormones had no function in the normal development of male bodies. Instead, they conceptualized female sex hormones as agents that caused diseases, in particular sexual and psychological disorders. Others suggested that female sex hormones affected a specifically female development, thus focusing research on homosexuality.21 The issue of hormones and homosexuality will be elaborated further in Chapter 3.
By the end of the 1930s, scientists had largely accepted the idea that “heterosexual hormones” have a function in the normal development of male organisms, thus abandoning the dualistic concept of an exclusive sex-specific hormonal function. This led, in turn, to the reconsideration of another assumption in the original conceptualization of sex hormones. At the moment that the idea of the sex-specific function of sex hormones was overthrown, scientists questioned the concept of sex antagonism as well. If female sex hormones were present in male bodies, it was hard to maintain the idea of an antagonistic effect on the development of male sexual characteristics. In the early 1930s, the idea of an antagonism between male and female sex hormones was widely disputed. In this debate we see again how the disciplinary background of scientists structured their claims. From a chemical perspective, Ernst Laqueur, professor at the Pharmaco-Therapeutic Laboratory at the University of Amsterdam, rejected the idea of sex antagonism in 1935 as follows: “Our chemical knowledge makes the original exaggerated assumption of the antagonism between male and female substances rather unlikely” (E. Laqueur 1935).
We saw above how biochemists had defined sex hormones as chemically related compounds. In this definition it is not necessary to assume an antagonistic relationship between sex hormones; other relationships are possible as well. This enabled the Amsterdam School to emphasize a different relationship between female and male sex hormones: instead of an antagonism they reported on the cooperative actions of sex hormones in the development of male secondary sexual organs such as the seminal vesicles, the ductus deferens and the prostate gland. Other scientists reported synergistic actions of male and female sex hormones in female rats, in such processes as stimulation of the growth of the uterus, the first opening of the vagina, and changes in the uterus similar to those seen during pregnancy— processes “typical of the most female sexual function” (Korenchevsky et al. 1937).
In this debate about sex antagonism, we see how sex endocrinologists actively transformed the prescientific idea that femininity and masculinity reside in the gonads. The American researchers Carl Moore and Dorothy Price, both experimental biologists from the Department of Zoology of the
University of Chicago, extended the conceptualization of sex from the gonads to the brain. In 1932, they postulated the idea of a feedback system between the gonads and the hypophysis—that is, they suggested that the inhibiting effects of female sex hormones on male sexual characteristics could not be understood in terms of a direct antagonistic effect on the male gonads, but rather in terms of a depressing effect of female sex hormones on the hypophysis, thus diminishing the production of male sex hormones by the gonads (Moore and Price 1932). In 1939, Frank Lillie evaluated these developments in Sex and Internal Secretions as follows:
If both sex hormones were present simultaneously.. .there should be an “antagonism” of the two hormones, each striving, so to speak, to control the development of the sex character in question. Such an antagonism was in fact postulated by earlier workers in this field, e. g., Steinach, but more recent work, especially that of Moore, seems to remove the necessity of assuming any antagonism in the simultaneous action of the two hormones, by showing that each operates independently within its own field.
(Lillie 1939:12)
In the late 1930s, the hypothesis of an endocrine feedback system was gradually accepted as the theory to explain interrelations between male and female sex hormones.22 Scientists thus transformed the prescientific idea that the essence of femininity and masculinity resides in the gonads into a conceptualization of sex that included the brain as the organ that controls sexual development. The extension of the conceptualization from the gonads to the brain also included the postulation of a new type of hormone: the gonadotropic hormones. In 1930, Bernhard Zondek, then working at the Department of Obstetrics and Gynecology at the City Hospital in Berlin, suggested that “the motor of sexual function” is located in a specific part of the hypophysis, the pituitary gland, which produces two separate chemical substances. The function scientists ascribed to these “master hormones” was to induce the gonads to produce sex hormones (Zondek 1930:245; Zondek and Finkelstein 1966).
Additionally, scientists reshaped the prescientific idea of a sexual duality located in the gonads. Initially, scientists had translated this cultural notion into the idea that there existed just two sex hormones, one per sex. In the 1930s, scientists dropped the claim of the existence of just one single female sex hormone. Scientists now suggested that the ovaries are capable of producing two distinct types of female sex hormone. The “one hormone” doctrine was gradually replaced by the theory that different parts of the ovaries secreted two separate chemical substances. Between 1929 and 1930, three research groups in Europe and in the United States reported the isolation of chemical substances originating from the follicular fluid of the ovaries, which they named estrogenic hormones. By 1934, research groups reported the isolation of “a second female sex hormone” that, as they claimed, originated from another part of the ovaries: the corpus luteum. This hormone ecame known as progesterone. From this time onwards, the idea of a single female sex hormone finally disappeared (Parkes 1966:21). Some scientists depicted progesterone as “the most female type” of the female sex hormones, because this hormone was considered as sexual-specific in origin (Jongh 1936:5,370). Other scientists suggested that this “second” female sex hormone was the more masculine of the two hormones, emphasizing its similarity in function with male sex hormones (Klein and Parkes 1937).
The 1930s were tumultuous years. Scientists reconsidered earlier assumptions about the function of sex hormones as well. In the original concept, sex hormones were understood as substances that affected only those anatomical features which were related to sexual characteristics. In the 1930s, however, reports were published suggesting that the hormones were not so restricted in their function: experiments were described in which they affected the weight of the hypophysis and liver, nitrogen metabolism, and total body weight (Korenchevsky and Hall 1938:998). As had happened before, scientists adopted a new perspective on the function of sex hormones. After 1935, sex hormones were no longer considered as exclusively sex — specific in function, nor as merely sex hormones or antagonists; instead, they were seen as substances that could generate manifold synergistic actions in both the male and the female body. In this manner, sex endocrinologists thoroughly transformed the prescientific idea of a sexual duality located in the gonads.