The framework of evolutionary theory will be increasingly adopted as the foundation for a cumulative understanding of psychological science. As the unifying theory of the life sciences, evolution by natural and sexual selection offers an unparalleled ability to integrate currently disparate research areas (Wilson, 1998), creating a powerful framework for understanding the complex patterns of causality in psychological and behavioral phenomena. The evolutionary perspective will grow from its perceived status as a special interest area into an organizing principle that pervades every corner of every field, as well as serve as a bridge across levels of analysis.
The incorporation of evolutionary theory into psychology has waxed and waned in the 150 years since Darwin (1859) predicted that the field would be based on a new foundation. There are many notable examples of psychological theories with evolutionary bases, such as Bowlby’s (1969) model of attachment, yet these are often isolated examples. In the last three decades, the evolutionary perspective has been reinvigorated with considerable theoretical advances and a continually growing array of empirical studies.
Claims for such dramatic advancements on currently held beliefs likely evoke skepticism. The massive empirical evidence accumulating for the influence of evolutionary selection pressures on psychological mechanisms will convince objective observers. It is important to note that evolutionary explanations will not necessarily replace the current models for specific psychological and behavioral phenomena, but rather integrate the “how” with the “why.” It may help to recognize that evolutionary psychology is not monolithic; there are multiple levels of theory from basic principles to specific phenomena and multiple competing explanatory theories. Disagreements occur even between those considered the founders of the modern field. For example, some believe in psychological adaptations that facilitate homicide (Buss, 2005) whereas others believe that homicide is the product of adaptations for sub-lethal motivations such as competition combined with lethal modern technology (Daly & Wilson, 1988).
It may also help to distinguish modern evolutionary psychology from the selective breeding programs in previous eras of human history. There is no teleology in evolution; no person or people are more highly evolved than any other persons or peoples. Everyone alive today is descended from a long, long line of successful ancestors. Yet there may be individual and group differences in psychological domains that are partially a result of differential selection pressures on ancestral populations. Humans have colonized nearly every land area on the surface of the earth, and each of these diverse ecologies could shape our psychological design. Efforts to advance human welfare may benefit from this recognition, as well as the understanding that genes are not the script for a pre-ordained destiny. Everything about us as individuals is a product of complex interactions between our genetic instructions and aspects of the environments in which they are expressed.
By providing the broader context in which research results may be interpreted, researchers across fields will facilitate the integration of a larger body of scientific knowledge. The evolution of psychology will facilitate its recognition and integration as science.
Bowlby, J. (1969). Attachment and loss, vol. 1. New York: Basic Books.
Buss, D. M. (2005). The Murderer Next Door: Why the Mind is Designed to Kill. New York: Penguin Press.
Daly, M., & Wilson, M. (1988). Homicide. New York: Alidine de Gruyter.
Darwin, C. (1859). On the Origin of Species by Means of Natural Selection. London: John Murray.
Wilson, E.O. (1998). Consilience: The Unity of Knowledge. New York: Alfred A. Knopf.