Jason Richwine examines political scientist Robert Putnam's findings on diversity:
When he spoke to my class in 2004, Putnam had started to analyze the survey data, but he had not yet published any findings. He began by telling us about one result he encountered that was thoroughly upsetting to him—the more ethnically diverse a community is, the less social capital it possesses. When a person lives in a diverse community, he trusts everyone less, including those of his own ethnic group. In describing the behavior of people in diverse areas, Putnam told us to imagine turtles hiding in their shells.