Evolution and the Bounds of Human Nature

Does an evolutionary analysis of human behavior permit the identification of meaningful limits on social, political, and economic life? This article argues that, although the evolutionary paradigm is valid and applies to human psychology, an informed understanding of the full range of mechanisms thought to operate in human evolution undermines the predictive value of evolutionary analysis and vitiates the political significance of evolutionary models of human development. Those mechanisms include sexual selection, which is the process by which organisms choose their mates, and group selection, which operates through resource and reproductive competition between groups. The analytic framework accepted by many scholars applying evolutionary theory to social questions posits that behavioral programs that were most widely adaptive, or fitness-enhancing, for individuals during remote periods of evolutionary development will be widely retained in the human population and will exert strong controls over behavior today. The use of this model to identify psychological tendencies that are the most "hard-wired" - and thus the most resistant to social manipulation - depends on an accurate description of the past evolutionary environment. This in turn permits the identification of behaviors that most enhanced reproductive fitness in that setting and that are most likely to be expressed today. This speculative inference works best for establishing a link between material aspects of the past environment and the physical survival of the individual organism. It works less well when other elements of reproductive fitness - including those favored by sexual selection and group selection mechanisms - are added to the mix. These mechanisms confound the analysis by obscuring which behaviors most enhanced overall fitness in past environments. This in turn impedes the identification of behaviors that will now most resist change. Unlike behaviors that increase sexual opportunities by enhancing physical survival, those that do so by appealing to the opposite sex do not necessarily respond to resource constraints and are difficult to infer from our knowledge of past physical environments. Indeed sexual selection, by sometimes favoring wasteful display, can propagate tendencies that are otherwise non-adaptive, in the sense of rendering the individual organism less able to survive and thrive. Likewise, because groups out compete rivals when members act to benefit others, the forces of group selection can foster conformance to demanding group norms that work against individual advantage. The predictive enterprise is made even more indeterminate by a lack of information about the extent to which pre-historic social conditions were conducive to group selection. The article concludes that whether particular behaviors appear to have conferred a survival advantage for most people in the past says very little about whether they will dominate social life or whether they can effectively be controlled under modern social conditions. Because present inflexibility cannot be derived from past individual adaptiveness, evolutionary theory sheds little light on the possibilities for social progress and behavioral change.