The first challenges to the prescientific idea of a sexual duality located in the gonads appeared in the early 1920s. In 1921, the Viennese gynecologist Otfried Fellner published an article in Pflueger’s Archiv describing experiments with rabbits in which extracts of the testis produced effects on the growth of the uterus similar to those produced by ovarian extracts. Fellner suggested that the testis of the rabbit obviously contained female sex hormones (Fellner 1921:189).14 It took several years before this report evoked reactions from his colleagues. Remarkably, this response came from the “newcomers” in the field of sex endocrinology: the biochemists. The biochemical focus on the chemical identification and isolation of sex hormones generated a new set of needs for raw materials, amongst others urine (Clarke 1987b:331).15 In this biochemical search for new resources to obtain female sex hormone (to replace the expensive ovaries), scientists reported the presence of female sex hormones in men. Ernst Laqueur’s research group at the Pharmaco-Therapeutic Laboratory of the University of Amsterdam—the Amsterdam School, as they were known by other scientists—reported in 1927 that female sex hormone was present not
February 10, 1934 NATURE
Letters to the Editor
[The Editor does not hold himself responsible for opinions expressed by his correspondents. Neither can he undertake to return, nor to correspond with the writers of, rejected manuscripts intended for this or any other part of Nature. No notice is taken of anonymous communications.]
Mass Excretion of (Estrogenic Hormone in the Urine
of the Stallion
In earlier investigations1 it was shown that the largest quantities of oestrogenic hormone (folliculin— g. oestrin) are excreted in the urine of pregnant mares (100,000 mouse units per litre). I found this also to be the case in other equines (ass, zebra) during pregnancy, whereas, in the non-pregnant state, the excretion of hormone both in equines and in other mammals is very small, at most 0-5 per cent in comparison with that of the gravid animal. Curiously enough, as a result of further investigations, it appears that in the urine of the stallion also, very large quantities of oestrogenic hormone are eliminated.
Figure 2.1 Bernhard Zondek’s Letter to the Editor of Nature in which he announces the presence of “restrogenic hormone” in the urine of the stallion.
Source: Zondek (1934a) only in the testis but also in the urine of “normal, healthy” men. (E. Laqueur et al. 1927b:1,859).
What really made an impact was an article which appeared in 1934 in Nature by the German gynecologist Bernhard Zondek, then working at the Biochemical Institute of the University of Stockholm (Figure 2.1).16 In this article, entitled “Mass excretion of astrogenic hormones in urine of the stallion”, Zondek described his observations as follows:
Curiously enough, as a result of further investigations, it appears that in the urine of the stallion also, very large quantities of restrogenic hormone are eliminated…. I found this mass excretion of hormone only in the male and not in the female horse. The determination of the hormone content, therefore, makes hormonic recognition of sex possible in the urine of a horse. In this connexion we find the paradox that the male sex is recognized by a high restrogenic hormone content.
(Zondek 1934a)
In the same publication Zondek reported that “the testis of the horse is the richest tissue known to contain estrogenic hormone.” One month later he published a second article in Nature describing the identity and the origin of female sex hormones in males.17 Zondek’s observations were startling at the time. Who could have expected that the gonads of a male animal would turn out to be the richest source of female sex hormone ever observed?
The female of the species did not escape this confusion: in the same period, reports were published of the presence of male sex hormones in female organisms—but it is interesting that this phenomenon received far less attention. The articles indexed in the Quarterly Cumulative Index Medicus show that the number of articles written on females is considerably less than on males.18 The first publication reporting the presence of male sex hormone in female organisms was published in 1931 by the German gynecologist Siebke. In 1932, this observation was confirmed by Elisabeth Dingemanse, a biochemist from the Amsterdam School (Jongh 1934b). In the years to follow, the British physiologist Hill published a series of contributions under the flagrant title, Ovaries secrete male hormone (Evans 1939:597).
The above observations contradicted the original concept of the sexual specificity of sex hormones. What label should be attached to substances isolated from male organisms possessing properties classified as being specific to female sex hormones, and vice versa? Scientists decided to name these substances female sex hormones and male sex hormones, thus abandoning the criteria of exclusively sex-specific origin. Female sex hormones were no longer conceptualized as restricted to female organisms, and male sex hormones were no longer thought to be present only in males. Here we see how scientists gradually moved away from the prescientific idea that the essence of femininity is located in the ovaries, while the testes are the seat of masculinity. This shift in conceptualization led to a drastic break with the dualistic cultural notion of masculinity and femininity that had existed for centuries.
Because the prescientific idea of a sexual duality located in the gonads had dominated research for years, scientists were rather taken aback by the idea that female sex hormone could also be found in male bodies.19 In the first reports these results were evaluated as “one of the most surprising observations in the sex hormone field” and “a strange and apparently anomalous discovery”; the reports contained phrases like “curiously enough,” “unexpected observation” and “paradoxical finding” (Frank 1929: 292; Jongh 1934b:1,209; Parkes 1938; Zondek 1934a:209).
Many scientists found their own results so surprising that they felt obliged to emphasize the fact that they had used the urine and blood of “normal, healthy men and women.” In The Female Sex Hormone, Robert Frank, a gynecologist at Mount Sinai Hospital in New York, legitimized the identity of his test subjects by the statement that he had observed female sex hormones in the bodies of males ‘whose masculine character and ability to impregnate females” were unquestioned (Frank 1929:120). Other scientists, however, concluded that the tested subjects, though apparently normal, were “latent hermaphrodites” (Parkes 1966:26).