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.
Raja (festival)
According to popular belief as women menstruate, which is a sign of fertility, so also Mother Earth menstruates. So all three days of the festival are considered to be the menstruating period of Mother Earth. During the festival all agricultural operations remain suspended. As in Hindu homes menstruating women remain secluded because of impurity and do not even touch anything and are given full rest, so also the Mother Earth is given full rest for three days for which all agricultural operations are stopped. Significantly, it is a festival of the unmarried girls, the potential mothers. They all observe the restrictions prescribed for a menstruating woman. The very first day, they rise before dawn, do their hair, anoint their bodies with turmeric paste and oil and then take the purificatory bath in a river or tank. Peculiarly, bathing for the rest two days is prohibited. They don't walk bare-foot do not scratch the earth, do not grind, do not tear anything apart, do not cut and do not cook. During all the three consecutive days they are seen in the best of dresses and decorations, eating cakes and rich food at the houses of friends and relatives, spending long cheery hours, moving up and down on improvised swings, rending the village sky with their merry impromptu songs.