It is easier for the brain to first quantify objects into pairs and then to differentiate them into opposing groups: right or wrong, light or dark, Republican or Democrat, good or evil, etc. This neural process of simplification and generalization is a form of biological stereotyping because it does not take into account individual differences and nuances. Once an oppositional dyad is created, the brain will then impose an emotional bias on each (e.g., it will root for a favorite sports team and disparage the other). This oppositional dyad includes people from different cultural, religious, and ethnic backgrounds. Unfortunately, this inborn us-versus-them mentality converts easily into racism. (Newberg, Andrew, MD and Mark Robert Waldman. Why We Believe What We Believe. P 87-92. NY:Free Press, 2006)