In Sex and Culture (1934), Unwin studied 80 primitive tribes and 6 known civilizations through 5,000 years of history and found a positive correlation between the cultural achievement of a people and the sexual restraint they observe.

1. Some Women That Never Evolved 2. An Initial Inequality 3. Monogamous Primates: A Special Case 4. A Climate for Dominant Females 5. The Pros and Cons of Males 6. Competition and Bonding among Females 7. The Primate Origins of Female Sexuality 8. A Disputed Legacy.