Scott Alexander examines the hypothesis that sexual purity taboos evolved to prevent STI spread, considering historical STI prevalence and cross-cultural taboos. Longer summary

Scott Alexander explores the hypothesis that cultural evolution created sexual purity taboos to prevent the spread of sexually transmitted infections (STIs). He discusses the historical prevalence of STIs, particularly syphilis, and examines common sexual purity taboos across cultures. The post considers both STIs and false paternity as potential drivers of these taboos, weighing evidence for each. Scott also investigates taboos on homosexuality, discussing their variation across cultures and potential links to STI transmission. While he concludes that STIs likely played a role in the evolution of these taboos, he acknowledges that the evidence is circumstantial and more research is needed. Shorter summary