Throughout history, menstruation has been associated with myth and superstition. Menstrual blood was felt to cure leprosy, warts, birthmarks, gout, worms and epilepsy. It has been used to ward off demons and evil spirits. Menstruating women have been separated from their tribes in order to prevent a bad influence on the crops or the hunt. As recently as 1930, the cause of abnormal menstrual bleeding was felt to be an undue exposure to cold or wet just prior to the beginning of the period.