Why do humans get into groups to kill other groups of humans?

Answer 1

it is a style many people do the wrong things just to fit in with the so called cool crowd. like to try to get into gangs you would have to show that you are strong enough to handle life on the streets. other times people get in to gangs to make them look or feel strong. now if one gang or group kills another group it would be for reasons like a person of one group has a problem with a person of another group that would man that the whole group has a problem.another reason why is for the reason of space their turf gangs would fight for their space sometimes even kill each other.

The reasons for this behavior (which can go from small scale gangs to large scale global wars) are complex and often intertwined. what is often the reason is loyalty to one's group (usually a nation or country) who's leader has declared war (oftentimes fueled by greed, but other times for the protection of innocents). Revenge, greed for power, simple insanity, etc are usually the causes

Answer 2

Humans may form groups to gain power, resources, or protect their interests, which can sometimes lead to conflicts with other groups. Additionally, factors such as fear, prejudice, competition, and desire for control can also play a role in group violence towards others.