ancestors took their first steps out of Africa. If we are thinking about an evolved psychology for bonding with members of our own group and fighting those outside, our ancestors would have been blind to race as it was not yet an emergent property of our species. Language was, however, a property of our species, and one that varied across populations. A hunter-gatherer walking the plains of South Africa would indeed have run into people speaking either a completely different language, or the same language with a different dialect. New languages are not easily acquired, and nor are new dialects. It takes real talent to speak a new language or dialect without a trace of ones origins. Thus, like the stotting gazelles, magnanimous spenders, and healthy evildoers discussed in chapter 2, the native languages and dialects we speak are honest signals of social group membership. Honesty is supported by the costs we pay to acquire them. Cheating is hard because there is a start-up cost associated with perfecting the natural rhythm of a second language or novel dialect. The babies in Kinzler’s experiments tell us something important: race and language are both important social categories and discriminable from an early age. But language trumps race as a feature because it is a better predictor of membership within the inner sanctum, at least early in life. Ultimately, both language and race allow us to close off some from the inner sanctum and allow others in. Ultimately, our allegiance to our native language and race can fuel our hatred toward those who look different and speak in different tongues. Closed doors As adults, we tend to rely on rules of thumb to guide our social interactions, including who we trust and who we distrust. We tend to trust those we know more than those we don’t know. Within the circle of those we know, we believe those who are more like us than those who are unlike us, using fixed body features — race, height, hair color — flexible psychological