ABSTRACT
A s the chapters in this volume attest, evolutionary principles can explain and integrate much of what is currently known about human social behavior. This is particularly true of mating and parenting, two life tasks that are closely linked to inclusive fitness. At base, evolutionary approaches seek to understand human psychological design—the nature, organization, and operation of specific psychological mechanisms—through identifying plausible constraints imposed by past selection pressures. Human behavior is highly flexible and exquisitely sensitive to environmental stimuli and feedback. Nevertheless, as Tooby and Cosmides (1992) have argued, psychological designs that produce “plasticity” can be retained by selection “only if they have features that guide behavior into the infinitesimally small regions of relatively successful performance with sufficient frequency” ( p. 101 ). Consequently, in order to understand and explain behavioral flexibility, one must comprehend the psychological architecture that underlies social interaction.
