| Its a refinement of the instinct of Tribalism.
This is my own theory, so don't expect references; I use the term "Tribalism" as a broad description of all groupings.
People seem to identify with whatever group of people they are a part of, and they feel threatened by or feel hatred of outsiders. Racism and Religious factions have been blamed for a lot of the world's problems, but these are just examples of Tribalism which is much broader. In can be a sports team or sports supporters club. It can be ethnic, such as in the former Yugoslavia where it wasn't exactly racism as the tribes were the same race, but not the same culture. It occurs in office politics, where a team will very easily start to think of another team as "that useless lot".
All of this can be constructive; a good manager or a good political leader can promote healthy rivalry between sales teams or sports clubs, and it can be positive as when patriotism is necessary when a society or country is under a genuine threat, and the individuals have to give up some of their individuality for the good of the whole. Or it can be very destructive, as in Volksgemeinschaft, or the gang warfare we see in the streets of most major cities in the world. |