David M. Buss
This section of the handbook considers evolutionary psychology as it infuses different disciplines that may at first seem far removed from the evolutionary sciences. Four of the five chapters are entirely new, reflecting how far and how deeply evolutionary psychology has influenced adjacent disciplines.
The first focuses on evolutionary anthropology, written by Dan Fessler, Jason Clark, and Edward Clint. The authors highlight the ways in which evolutionary psychology can be informed and enriched by evolutionary anthropology, and reciprocally, the ways in which evolutionary anthropology can be informed and enriched by evolutionary psychology. They stress the importance of tools such as phylogenetic analysis, exploitation of primatological comparisons, the study of small traditional societies, the use of anthropological data banks of ethnographies that can be analyzed quantitatively, the use of modern techniques emerging from genetics, and the “kludge-like” nonoptimal nature of adaptations. It's an exciting chapter that should foster increased cross-disciplinary collaborations between evolutionary psychologists and evolutionary anthropologists who, although often operating within the paradigms of their respective guild-like coalitions, truly have much to offer each other.
The second new chapter, written by Reuben Arslan and Lars Penke, deals with evolutionary genetics—a field that was virtually absent a decade ago. Evolutionary genetics focuses on the mechanisms that explain the existence and maintenance of genetic variation in traits. In decades past, it was widely believed that natural selection exhausted genetic variation. Biologists and geneticists have been increasingly astonished to discover large reservoirs of genetic variation—differences that lead to manifest individual differences—that must be explained. These authors review the candidate evolutionary forces that create and maintain genetic variation within a species. The evolutionary genetics toolkit offers evolutionary psychologists an array of methods for the rigorous testing of some evolutionary psychological hypotheses. Evolutionary genetics enriches evolutionary psychology. It provides a theoretical framework for integrating individual differences and recent evolution, bringing us closer to understanding why we are the way we are and the causal processes by which we became that way.
Evolutionary endocrinology offers yet another scientific toolkit for evolutionary psychology, as represented by a superb new chapter by James Roney. He notes that a complete understanding of evolved psychological adaptations requires deep understanding of “Tinbergen's Four,” which include phylogeny, ontogeny, adaptive function, and neurobiological implementation. Evolutionary endocrinology offers a set of tools for illuminating all four explanatory levels. Roney makes his case by outlining what is known about the evolutionary endocrinology of mating—an especially apt target of selection, given that it is so close to the “engine” of evolution by selection, differential reproduction. He concludes aptly: “No model of human nature will be complete without a clear understanding of the functional roles of these chemical messengers.”
Evolutionary psychology is beginning to infuse political science, and Michael Bang Petersen provides the road map for a deeper and richer integration. Humans have been called “the political animal” for a good reason—politics is all about “games” in which players have conflicting interests and lobby to determine “who is entitled to what, when, and how.” Peterson outlines the fundamental premises of evolutionary political psychology, starting with “Evolved political psychology is designed to operate adaptively within and between small-scale groups.” He proceeds to discuss the coevolution of information manipulation strategies and counter-strategies. Petersen shows how adaptations for politics in small-group living get played out in the modern settings of massive populations. Along the way, he unearths an important collection of psychological adaptations for politics, including those of negotiating status, reputation, power, coalitional allegiance, political leadership and followership, persuasion, moralization, and information manipulation. Peterson's chapter is likely to serve as a beacon for political scientists, providing not the final word, but the first key outlines of a road map for the field ahead.
The final contribution is a chapter by Joseph Carroll on evolutionary psychology and literature. Traditionally, science and the humanities (and particularly the arts) have been regarded as separate endeavors. Carroll, in a conceptually synthetic essay, argues for consilience—a unified causal understanding that integrates the sciences and humanities. He reviews the various approaches to the evolutionary analysis of literature, including the key themes of human nature reflected in literature and the possibility of adaptations for producing literature and its oral antecedents. The evolutionary analysis of literature and the arts is beginning to flourish, and Carroll's excellent chapter takes stock of where this exciting enterprise has been and where it promises to go.
Evolutionary psychology has penetrated many disciplines, and space limitations unfortunately precluded inclusion of all of them. As these words are written, there are rapidly emerging new hybrid disciplines, such as evolutionary economics, evolutionary organizational behavior, evolutionary sociology, and evolutionary analyses of history. In the final analysis, all human behavior—including economic behavior, legal behavior, artistic behavior, and organizational behavior—is a product of evolved psychological mechanisms and the environments within which those mechanisms operate. I predict that in the distant future, all of these diverse and seemingly unrelated fields will be based on a new evolutionary foundation.