I primarily research psychological adaptations for processing ethnic and coalitional social categories. I address these cognitive questions through cross-cultural research in the United States and along the Quechua-Aymara border in the Peruvian altiplano. Questions of interest include: 1) Which social stereotypes are humans prone to form, 2) How do children learn which social categories are useful bases for making predictions, 3) Do humans essentialize certain categories and if so is there a functionalist account that helps explain why?