The potency of the butterfly: The reception of Richard B. Goldschmidt’s animal experiments in German sexology around 1920

This article considers the sexual politics of animal evidence in the context of German sexology around 1920. In the 1910s, the German-Jewish geneticist Richard B. Goldschmidt conducted experiments on the moth Lymantria dispar, and discovered individuals that were no longer clearly identifiable as male or female. When he published an article tentatively arguing that his research on ‘intersex butterflies’ could be used to inform concurrent debates about human homosexuality, he triggered a flurry of responses from Berlin-based sexologists. In this article, I examine how a number of well-known sexologists affiliated with Magnus Hirschfeld, his Scientific-Humanitarian Committee, and later his Institute of Sexology attempted to incorporate Goldschmidt’s experiments into their sexological work between 1917 and 1923. Intersex butterflies were used to discuss issues at the heart of German sexology: the legal debate about the criminalisation of homosexuality under paragraph 175; the scientific methodology of sexology, caught between psychiatric, biological, and sociological approaches to the study of sexual and gender diversity; and the status of sexology as natural science, able to contribute knowledge about the sexual Konstitution of the organism. This article thus shows that butterfly experiments function as important and politically charged evidence for a discussion at the heart of the sexological project of those involved in the founding of the Institute of Sexology: the question of the nature and naturalness of homosexuality (and sexual intermediacy more broadly) and its political consequences. In doing so, this article makes a case for paying attention to non-human actors in the history of sexology.