Menstruation
Most female mammals have an estrous cycle, yet only ten primates species, four bats species, the elephant shrew, and the spiny mouse have a menstrual cycle. The relatedness of these groups suggests that four distinct evolutionary events have caused menstruation to arise.
Culture and menstruation
In some historic cultures, a menstruating woman was considered sacred and powerful, with increased psychic abilities, and strong enough to heal the sick. According to the Cherokee, menstrual blood was a source of feminine strength and had the power to destroy enemies. In Ancient Rome, Pliny the Elder wrote that a menstruating woman who uncovers her body can scare away hailstorms, whirlwinds and lightning. If she strips naked and walks around the field, caterpillars, worms and beetles fall off the ears of corn. Menstrual blood is viewed as especially dangerous to men's power. In Africa, menstrual blood is used in the most powerful magic charms in order to both purify and destroy.
Mayan mythology explains the origin of menstruation as a punishment for violating the social rules governing marital alliance. The menstrual blood turns into snakes and insects used in black sorcery, before the Maya moon goddess is reborn from it.