Role of the hormones in human sexuality.

T HE mechanism of sexual behavior has long been an intriguing although frustrating subject of investigation. With the discovery of the role of the gonads as producers of hormones, and particularly after the isolation, purification, and synthesis of the steroid hormones, biologists believed that a simple explanation of sexual behavior was at last available. Many observers had noted that sexual behavior in animals was species-specific and that these typical sexual patterns could be eliminated or altered by castration so that copulation was not attempted. After purified steroid hormones became available for experimental use, it became apparent that estrogenic materials, administered to the castrate female animal, often were able to reestablish her sexual pattern and that androgenic materials, administered to the castrate male animal, were similarly effective. When it became possible to measure the excretion of hormonal products, it was observed that in lower animals, females mated only when estrogenic production was at its height. This lent further proof to the thesis that sexual behavior was under direct and specific hormonal control. Observations of mating behavior of higher animals revealed some discrepancies in this concept. This was particularly true of the chimpanzee. The female chimpanzee was seen to mate at any phase of her cycle and would often continue to engage in the sex act even though castrated. The castrate male chimpanzee was observed to seek the female and copulate or attempt to copulate with her. There seemed to be a breaking away from the strict hormonal control of sexual behavior in higher animals.