Diversity is not our strength. In-group cooperation wins over any other strategy in the long run.
Ethnocentrism is rational, biological, and genetic in origin. Source:
http://www.pnas.org/content/108/4/1262.abstract
Babies demonstrate ethnocentrism before exposure to non-Whites. Source:
http://onlinelibrary.wiley.com/doi/10.1111/j.1467-7687.2012.01138.x/full
Ethnocentrism is universal and likely evolved in origin. Source:
http://www-personal.umich.edu/~axe/research/AxHamm_Ethno.pdf
Races are extended families. Ethnocentrism is genetically rational. Source:
http://www.amazon.com/The-Ethnic-Phenomenon-Pierre-Berghe/dp/0275927091
Ethnocentrism is biological in origin and a superior evolutionary strategy to altruism. Source:
http://jasss.soc.surrey.ac.uk/16/3/7.html
Humans are more altruistic to individuals who they are more closely related to. Source:
http://www.ncbi.nlm.nih.gov/pubmed/17456276
People subconsciously prefer those who are genetically similar to them for biologically rational reasons. Source:
http://www.psychology.uwo.ca/faculty/rushtonpdfs/Genetic%20Similarity%201989.pdf
Kinship between members of an ethnic group is greater than expected. Source:
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.372.1009