David M. Buss
The field of psychology historically has been organized around subdisciplines, such as cognitive, social, developmental, personality, and clinical. Evolutionary psychology, in many ways, dissolves these subdisciplinary boundaries. The topics of this Handbook are largely organized around adaptive problems and evolved psychological solutions. As a consequence, each of the traditional subdisciplines in the field of psychology has relevance to many psychological adaptations. Consider, for example, the evolved fear of snakes. This adaptation has an underlying cognitive (information-processing) architecture, emerges at a predictable point in development, is susceptible to social input through observing the fear reactions of others, shows stable individual differences, and can become dysfunctional or pathological. Examined through the lens of evolutionary psychology, the subdisciplinary boundaries of mainstream psychology appear somewhat arbitrary, and do not cleave nature at its natural joints.
Nonetheless, since most psychologists are trained within the coalitional guilds and conceptual frameworks of these traditional subdisciplines, it is useful to see how evolutionary psychologists can approach the main questions and problems of these subdisciplines. What can evolutionary psychology offer to these disciplines as they are traditionally conceived? What new insights can be brought to bear on them? The chapters in this section address these questions.
Peter Todd, Ralph Hertwig, and Urlich Hoffrage (Chapter 37) provide a fascinating evolutionary psychological analysis of the field of cognitive psychology. They show how fresh insights into traditional topics—attention, information representation, memory, forgetting, inference, judgment, heuristics, biases, and decision making—can be informed by evolutionary analysis. Reciprocally, they show how advances in cognitive psychology greatly aid evolutionary analyses. Todd, Hertwig, and Hoffrage provide compelling arguments that benefits of the merger flow both ways, since traditional cognitive psychology also has much to offer evolutionary psychology.
David Bjorklund, Carlos Blasi, and Bruce Ellis provide a chapter on evolutionary developmental psychology (Chapter 38). They offer important insights that challenge some traditional assumptions in developmental psychology. For example, one traditional assumption has been that psychological features in childhood are merely preparations for the fully functioning adult form. They argue persuasively that, instead, some adaptations are designed for specific stages of development and are appropriately functional at those times, rather than serving merely as way stations to the development of the adult form. They consider how evolutionary analysis of many topics central to developmental psychology—topics such as theory of mind, children's intuitive mathematics, and social behaviors such as children's aggression and dominance hierarchies—can lead to fresh insights that have been entirely missed by the traditional conceptual frameworks that have guided developmental psychology.
Douglas Kenrick, Jon Maner, and Norman Li also argue persuasively for reciprocal benefits, this time flowing from evolutionary psychology to social psychology, and from social psychology to evolutionary psychology (Chapter 39). They propose that the traditional social psychological emphasis on situation specificity is highly compatible with evolutionary psychological approaches that emphasize domain specificity. They suggest that social psychologists can gain by adding ultimate explanations to their traditional proximate explanations. Finally, Kenrick, Maner, and Li provide an attractive taxonomy of social adaptive problems that could serve as a powerful organizing framework for social psychology.
Aurelio José Figueredo, Michael Woodley, and W. Jake Jacobs (Chapter 40) provide an exciting chapter on evolutionary personality psychology, with a special focus on what has been called “The General Factor of Personality.” They focus on an area that tends to be relatively neglected by evolutionary psychologists—stable individual differences. Figueredo and colleagues review empirical evidence, both from human and nonhuman animal studies, which supports the contention that individual differences in personality have been subjected to natural selection, sexual selection, and frequency-dependent selection. They then evaluate a hierarchical model of life history strategy. It is an important chapter, and one that augers well for a greater conceptual integration of individual differences within an evolutionary psychological framework that emphasizes species-typical psychological mechanisms.
Martie Haselton, Daniel Nettle, and Damian Murray present theory and empirical research on the evolution of cognitive biases in social interaction (Chapter 41). As such, their chapter elegantly links two traditional disciplines that historically have been separate—cognitive psychology and social psychology. They provide sound arguments that certain social cognitive biases are in fact designed and functional, resulting in better solutions to adaptive problems than cognitive mechanisms that “accurately” detected social signals. They call for an evolutionary reformulation of the entire “heuristics and biases” literature, which typically casts humans as making illogical and unfounded errors. This new line of work has already led to the discovery of new cognitive biases and offers much promise for the future discovery of additional adaptive biases. It also may lead to the detumescence of decades of work that has cast humans as fundamentally irrational and hopelessly muddled in their judgment and decision making.
Jerome Wakefield provides a penetrating analysis of the concepts of function and dysfunction, which should form the foundation for the field of evolutionary clinical psychology (Chapter 42). He argues that clinical psychology historically has lacked a coherent definition of disorder. Instead, the field has relied on intuitive, conflicting, and usually fuzzy notions of disorder and dysfunction. Evolutionary psychology provides clarification. Wakefield cogently argues that the only sensible definition of disorder requires the failure of a designed function. It follows that we need to know the designed function of psychological mechanisms as a prerequisite to understanding when they fail to function as designed. Wakefield also exposes several fallacies in arguments that mental disorders are naturally selected conditions, and draws implications for the DSM classification system of disorders. It is somewhat astonishing to realize that clinical psychology has proceeded for decades without a clear definition of mental disorder. Wakefield's chapter fills the needed lacuna.
In the final chapter in this section (Chapter 43), Randolph Nesse provides a broad analysis of evolutionary psychology and mental health, identifying eight contributions of an evolutionary analysis: It explains why humans are vulnerable to mental disorders, offers a functional understanding of behavior, fosters a deeper and more empathic understanding of individuals, explains how relationships work, provides a way to think clearly about developmental influences, provides a functional approach to emotions and their regulation, provides a foundation for a scientific diagnostic system, and provides a framework for considering how multiple causal factors can explain why some people get mental disorders while others do not. Nesse's compelling chapter should be required reading of everyone in clinical psychology.
Taken together, the chapters in this section provide a set of conceptual tools for evolutionizing each of the major subdisciplines within psychology. To the extent that the subdisciplines retain their inertial institutional boundaries, these chapters are invaluable. Ultimately, however, they may also contribute to the eventual demise of the traditional boundaries and pave the way for a unification of the field of psychology.