In all the controversy over the new DSM-5, it was inevitable that a long-standing fight over premenstrual syndrome would be revived. Eighty-five percent of women claim to have suffered from this disorder, but repeated research shows there's actually no relationship between daily moods and shifting monthly hormone levels. The debate is nothing new. In her classic 1993 feminist text The Mismeasure of Woman, Carol Tavris argued that the idea of PMS persists because it gives women an excuse to express anger and irritation in a culture that expects them to be unendingly cheerful and pleasant. (It also panders to the belief that women are irrational victims of their own hormones.) Being able to blame your socially incorrect emotions on chemical shifts is intoxicating: Tavris showed that even when confronted with evidence that menstruation doesn't affect mood, "Many women are highly resistant to the evidence that their beliefs and expectations about PMS might be influencing their symptoms."