Chapter 7: Family Planning in Evolution

Family Planning in Evolution , titled "Family Planning," investigates the evolutionary logic behind reproductive decisions, challenging the notion that animals practice altruistic birth control for the good of the species. A critical distinction is established between two types of activity: "child-bearing" (bringing new individuals into the world) and "child-caring" (nurturing existing offspring), with the argument that a stable evolutionary strategy must involve a mix of both rather than pure caring. The text critiques V.C. Wynne-Edwards' theory of group selection, which proposes that animals voluntarily restrict their birth rates and use social behaviors like territoriality and dominance hierarchies to prevent overpopulation and starvation. Instead, the chapter champions David Lack’s theory of optimal clutch size, which argues that reproductive regulation is selfish: individuals strive to maximize the number of surviving offspring, not just the total number of eggs laid. According to this view, having too many offspring is penalized by natural selection because resources become too diluted to support them, leading to lower overall survival rates. Consequently, behaviors such as flocking (epideictic displays) and territorial fighting are reinterpreted not as population censuses, but as selfish assessments of competition or strategic waiting games. The chapter also introduces the "Beau Geste Effect," suggesting that animals may deceive rivals into believing population density is higher than it is to induce them to reduce their clutch sizes. Finally, the discussion extends to humans, noting that the modern welfare state disrupts the natural link between family size and resource availability, making unnatural birth control necessary to avoid overpopulation and misery.