Are Ethnic Groups Biological “Species” to the Human Brain?

If ethnic actors represent ethnic groups as essentialized natural groups despite the fact that ethnic essences do not exist, we must understand why. This article presents a hypothesis and evidence that humans process ethnic groups (and a few other related social categories) as if they were species because their surface similarities to species make them inputs to the livingkinds mental module that initially evolved to process specieslevel categories. The main similarities responsible are (1) categorybased endogamy and (2) descentbased membership. Evolution encouraged this because processing ethnic groups as speciesat least in the ancestral environmentsolved adaptive problems having to do with interactional discriminations and behavioral prediction. Coethnics (like conspecifics) share many strongly intercorrelated properties that are not obvious on first inspection. Since interaction with outgroup members is costly because of coordination failure due to different norms between ethnic groups, thinking of ethnic groups as species adaptively promotes interactional discriminations towards the ingroup (including endogamy). It also promotes inductive generalizations, which allow acquisition of reliable knowledge for behavioral prediction without too much costly interaction with outgroup members. The relevant cognitivescience literature is reviewed, and cognitive fieldexperiment and ethnographic evidence from Mongolia is advanced to support the hypothesis.