A new theory integrating evolutionary and dynamical approaches is proposed. Following evolutionary models, psychological mechanisms are conceived as conditional decision rules designed to address fundamental problems confronted by human ancestors, with qualitatively different decision rules serving different problem domains and individual differences in decision rules as a function of adaptive and random variation. Following dynamical models, decision mechanisms within individuals are assumed to unfold in dynamic interplay with decision mechanisms of others in social networks. Decision mechanisms in different domains have different dynamic outcomes and lead to different sociospatial geometries. Three series of simulations examining trade-offs in cooperation and mating decisions illustrate how individual decision mechanisms and group dynamics mutually constrain one another, and offer insights about gene-culture interactions.Evolutionary psychology and dynamical systems theory have both been proposed as antidotes to the theoretical fragmentation that long characterized the field of psychology. Evolutionary psychologists have proposed that isolated psychological research topics such as aggression, taste aversion, language acquisition, mate selection, and spatial cognition can be connected to research on cultural anthropology, ecology, zoology, genetics, and physiology via principles of modern Darwinian theory (e.g