Culture and menstruation the ideal of synchronised tidal, lunar, menstrual and seasonal periodicities whose overall harmony (it is believed) confers spiritual power and fertility. To many, such cultural associations appear persuasive in view of the fact that in humans, the menstrual cycle quite closely approximates the moon's 29.5-day synodic cycle, unlike in chimpanzees (~36 days) or bonobos (~40 days). Statistical information from hunter gatherers is lacking, but where large-scale western studies focus on women's peak reproductive years—removing outlier values—the cycle length gravitates around 29.1–29.5 days, while the figure for women in their thirties shortens toward 28 days. In no extant human population has
Menstrual leave employ such woman on days of the menstrual period." While Japanese law requires that a woman going through especially difficult menstruation be allowed to take leave, it does not require companies to provide paid leave or extra pay for women who choose to work during menstruation. In South Korea, not only are female employees entitled to menstrual leave according to the Article 71 of the Labour Standards Law, but they are also ensured additional pay if they do not take the menstrual leave that they are entitled to. In Taiwan, the Act of Gender Equality in Employment gives women three