Just so stories and inference to the best explanation in evolutionary psychology

Abstract

Evolutionary psychology is a science in the making, working toward the goal of showing how psychological adaptation underlies much human behavior. The knee-jerk reaction that sociobiology is unscientific because it tells “just-so stories” has become a common charge against evolutionary psychology as well. My main positive thesis is that inference to the best explanation is a proper method for evolutionary analyses, and it supplies a new perspective on the issues raised in Schlinger's (1996) just-so story critique. My main negative thesis is that, like many nonevolutionist critics, Schlinger's objections arise from misunderstandings of the evolutionary approach.

Evolutionary psychology has progressed beyond telling just-so stories. It has found a host of ingenious special techniques to test hypotheses about the adaptive significance and proximate mechanisms of behavior. Naturalistic data using the comparative method combined with controlled tests using statistical analyses of data provide good evidence for a variety of hypotheses about behavioral control mechanisms — whether in nonhumans or in humans. For instance, the work of Gangestad and Thornhill on evolved mate preferences and fluctuating asymmetry of body type (FA) is a model of success. As the quantity and quality of evidence increase, we are entitled not just to regard such evolutionary hypotheses as preferable, but also as true. Such studies combine to show that the best explanation of “the psychic unity of humankind” — common patterns across societies, history, and cultures exposed by evolutionists — is the gendered, adapted, evolved species-typical design of the mind.