evolutionary traits of national;ism

Ethnically homogenous neighborhoods are beneficial for health.

https://www.mailman.columbia.edu/public-health-now/news/living-ethnically-homogenous-area-boosts-health-minority-seniors

Diversity in American cities correlates with segregation.

http://fivethirtyeight.com/features/the-most-diverse-cities-are-often-the-most-segregated/

Races are extended families. Ethnocentrism is genetically rational.

http://www.amazon.com/The-Ethnic-Phenomenon-Pierre-Berghe/dp/0275927091

It is evolutionarily rational to be friends with someone genetically similar to you.

http://www.livescience.com/46791-friends-share-genes.html

Racism and nationalism are rational and evolutionary advantageous strategies.

http://jasss.soc.surrey.ac.uk/16/3/7.html

Homogeneous polities have less crime, less civil war, and more altruism.

http://www.theindependentaustralian.com.au/node/57

States with little diversity have more democracy, less corruption, and less inequality.

http://www.theindependentaustralian.com.au/node/57