Marjorie Shostak's research with a small sample of !Kung women showed that, among these women,
there were strong expectations of premenstrual depression
knowing what phase of the menstrual cycle a woman was in was a good predictor of the woman's mood
knowing what phase of the menstrual cycle a woman was was not a good predictor or the woman's mood or behavior
the menstrual cycle had a stronger influence on these women's mood than did other factors such as the behavior of their husband and friends.