Abstract Few species cooperate as readily with non-relatives as humans do, and this chapter examines the evolved mechanisms that make large-scale group living possible. It draws on evidence from non-human primates and hunter-gatherer societies to show how kin-based and reciprocal alliances structure social hierarchies, regulate access to resources, and enhance survival in the face of predation, disease, and intergroup conflict. The chapter then explores the cognitive and emotional architecture that sustains cooperation, including theory of mind, social emotions, gossip, reputation, and cheater detection, showing how these mechanisms work together to enforce norms and deter free-riding. It considers the costs of group living alongside its benefits, addressing pathogen transmission, resource competition, and the tragedy of the commons as countervailing pressures. Finally, the chapter presents reciprocal altruism and norm enforcement as the evolutionary foundations of the trust and cohesion that characterise human social life.
Abstract Evolutionary psychology has generated as much controversy as it has evidence, and this chapter examines the major criticisms the field faces and how its proponents respond to them. It addresses methodological disputes including the reliance on WEIRD populations, the use of non-human primate models, and the difficulty of linking modern behaviour to ancestral fitness, showing how researchers have attempted to address each without always resolving them. The chapter then turns to ethical and political criticisms, examining claims that evolutionary accounts of sex differences, gender roles, and social hierarchy risk naturalising inequality, and considers the field’s response that explaining a behaviour is not the same as endorsing it. It explores debates over genetic determinism, adaptationism, and modularity, and considers how gene-environment interactions, epigenetics, and cultural evolution have complicated simple selectionist accounts of human psychology. Finally, the chapter reflects on what it means for a discipline to be self-correcting, arguing that evolutionary psychology’s engagement with its critics is itself evidence of scientific maturity rather than weakness.
Abstract This chapter presents the brain as an evolved adaptation, shaped over millions of years by natural selection to solve recurrent problems of survival and reproduction. It introduces the Environment of Evolutionary Adaptedness as the framework within which ancestral psychological mechanisms were calibrated, and examines critiques of adaptationism including spandrels, exaptations, genetic drift, and the debate over massive modularity. The chapter traces human brain expansion and its metabolic costs, evaluating the cooking hypothesis and the social brain hypothesis as competing and complementary explanations for encephalization. It introduces gene-culture coevolution, niche construction, and dual inheritance theory as frameworks for understanding how cultural and biological evolution interact. Finally, the chapter distinguishes evoked from transmitted culture, showing how both shape the expression of evolved psychological mechanisms across populations and environments.
Abstract This chapter defines evolutionary psychology as the scientific study of psychological adaptations shaped by natural selection and sexual selection, situating it within the broader history of evolutionary thought from Darwin through sociobiology to the modern discipline. It explains the distinction between obligate and facultative traits, genotype–phenotype interaction, and modular cognition, and outlines the methods used to reconstruct human’s evolved psychology, including cross-cultural studies, comparative research, genetic evidence, and the archaeological record. The chapter traces human evolution from early hominins to Homo sapiens, addressing interbreeding with Neanderthals and Denisovans and the diversification of the genus. It introduces Tinbergen’s four questions as a framework for integrating proximate and ultimate explanations of behaviour, and distinguishes evolutionary psychology from behavioural ecology. Finally, it outlines key mechanisms including natural selection, sexual selection, runaway selection, and kin selection, presenting behaviour as the product of an evolved psychological architecture shaped by ancestral survival and reproductive demands.
