> Help me to understand. Human nature, maybe? People seem to like to form groups based on some random similarity (supporting the same football team, driving

> Help me to understand. Human nature, maybe? People seem to like to form groups based on some random similarity (supporting the same football team, driving the same car model, believing in the same religion, being of the same race, etc..) and start fighting the opposite groups. My favorite example is the following trivia from the "Planet of the Apes" movie: "During breaks in filming, actors made up as different ape species tended to hang out together, gorillas with gorillas, orangutans with orangutans, chimps with chimps. It wasn't required, it just naturally happened."