The reasons women have menstrual periods have fascinated and baffled medics and philosophers in equal measure for millennia. This is unsurprising, given the curious nature of a monthly episode of blood loss that happens to healthy women. The connection between periods and fertility was well known, but it was not until the twentieth century, when scientists understood the role of the monthly process of ovulation, that the process was fully explained. That did not stop (normally male) medical thinkers from offering theories about why women naturally bled each month. In formulating and promoting these theories, they paid little attention to the effects menstruation had on women’s bodies and mood and sidelined the experiences of many women who have to cope with painful or heavy periods routinely.
We have recorded theories of menstruation going back over two millennia. In ancient Greece, men like Pythagoras, now best known for his mathematical theories, Aristotle and Hippocrates formulated their own conclusions on the nature of women’s bleeding. Aristotle, for example, concluded that menstrual blood was the matter on which an embryo was nourished in the womb. For him, the male contribution to conception was what animated the matter, but the female blood provided the ‘nutritive soul’ of the infant. Similarly, a Greek physician working in Rome called Claude Galen, building on the Hippocratic texts (which themselves perhaps had Egyptian/Mesopotamian antecedents), described the processes of the body in terms of the doctrine of the four humours, or four main fluids (blood, bile, melancholy and phlegm), which needed to be kept in perfect balance for people to keep well. Galen argued that it was necessary for women to bleed each month because they led comparatively sedate lives, which meant they were predisposed to accumulating too much blood in their bodies, known as a plethora of blood. This didn’t happen to men, Galen explained, because they worked harder and more physically than women, and so sweated out their excess humours.