Rob Henderson in Quillette:
Professor David M. Buss, a leading evolutionary psychologist, states in the introduction of his fascinating new book that it “uncovers the hidden roots of sexual conflict.” Though the book focuses on male misbehavior, it also contains a broad and fascinating overview of mating psychology.
Sex, as defined by biologists, is indicated by the size of our gametes. Males have smaller gametes (sperm) and females have larger gametes (eggs). Broadly speaking, women and men had conflicting interests in the ancestral environment. Women were more vulnerable than men. And women took on far more risk when having sex, including pregnancy, which was perilous in an environment without modern technology. In addition to the physical costs, in the final stages of pregnancy, women must also obtain extra calories. According to Britain’s Royal College of Obstetricians and Gynaecologists, pregnant women in their final trimester require an additional 200 calories per day, or 18,000 calories more in total than they otherwise would have required. This surplus was not easy to obtain for our ancestors. Men, in contrast, did not face the same level of sexual risk.