The author surveys the biological and social origins of marriage and the family, beginning with animal reproduction and mating behavior and proceeding through cross-cultural forms of sexual association. The study examines alleged promiscuity, hetaïrism, polyandry, marriage by capture, purchase and servitude, polygamy, primitive and civilized monogamy, prostitution and concubinage, adultery, repudiation and divorce, widowhood and the levirate. Drawing on ethnographic examples and comparative analysis, it traces how sexual customs, property relations, and evolving moral sentiments shape family arrangements across different societies.