People hate other people because of a primitive need to separate friends from foes, according to Emotional Competency. The human emotional spectrum is attuned to naturally experience feelings of distrust, caution and doubt upon initially meeting a new person. Stereotypical thinking is another strong catalyst for hatred of others.
The human mind naturally thinks in a separation of in-groups and out-groups. In the natural world, it is much more dangerous to believe a positive encounter is negative than the inverse, resulting in a predisposition to distrust those who are not part of the in-group. This eventually results in xenophobia, or a generalized hatred of the other. Likewise, the ability to hate another human allows an individual to shut off his empathy, which is an important trait in wounding or even killing another in the natural world.
Another strong cause of the hatred of others is rooted in fear. The unknown naturally causes a fear response, which often results in the expression of hatred or repulsion. Other reasons for hating other humans include fragility in self-esteem, the necessity to blame a person for impersonal misfortune, the basic human desire to increase a sense of community among in-groups, and certain logical errors.