The evolution and development of inferential reasoning about ethnic markers: Comparisons between urban United States and rural highland Peru

Social scientists have long argued about the relationship between ethnic phenomena, symbolic markers, and cultural traits. In this paper, we illustrate the potential of functionalist cultural and genetic evolutionary models to reconcile these debates. Specifically, we argue that we must take seriously the role of cultural similarity in delineating certain category boundaries if we are to understand the origins and development of ethnic stereotyping. We examine whether symbolic markers—namely, sartorial ones—are privileged in the development of social stereotypes by comparing how children and adults in the urban United States and rural highland Peru perform a categorization task. We find that arbitrary sartorial markers motivate generalizations about novel traits in all samples except among US children, even when they crosscut body morphology, emotional expression, and socioeconomic cues. Unlike children in the United States, children in the Peruvian sample demonstrate an even stronger reliance on sartorial and work site cues than do adults of the same community. This suggests a role for early-developing evolved biases that guide learning and require appropriate cultural inputs or different niches for adults and children. We document further cross-cultural variation, in that US participants privilege socioeconomic cues to occupational status more than other cues, whereas Peruvian participants rely on sartorial cues more than other cues, indicating the importance of cognitive rules for learning locally relevant social taxonomies.