Later, to their shock, scientists began to realize that significant levels of androgens were present in women and of estrogen in men. In 1934, the German-born gynecologist Bernhard Zondek, while studying stallion urine, reported on “the paradox that the male sex is recognised by a high oestrogenic hormone content.” In fact, a male horse’s testes turned out to be one of the richest sources of estrogen ever found.
