Why do we humans feel the need for revenge after we have been hurt or humiliated?

The bad thing has already happened to us. It is not like hurting the other person back will make it go away, and it may even make the whole situation escalate and get worse!

But for many people this is the first reaction, and a very strong urge. It seems to be in human nature. Why do you think that is?

Why do we humans feel the need for revenge after we have been hurt or humiliated?
Post Opinion