[barry-cotter]

Robert Putnam's research confirms that ethnic diversity reduces trust levels and civic engagement, even when the ethnic diversity is as risible as Norwegian vs Swedish Americans in, say, Minnesota. If I recall correctly he's a Harvard faculty member in either sociology or political science. He wrote Boewling Alone and he sat on those results for like, three years because his political preferences are typical for his position. The explanation the grandparent offered may be wrong but the phenomenom is real.