Basic psychology is, that when you don't need something around you, you get rid of it. Next is that when you don't care about some people around you, you get rid of them. Everyone is opposed to clutter, and everyone is opposed to people who they don't consider useful. But what if you live in a very patriarchal old culture and the person you don't consider useful is a family member? Domestic abuse and honor killing has its roots in this basic human instinct. Why do we feel that we need to get rid of things and people when we see them useless, but they don't hinder us in anything? As a starter, I propose that this is about the instinct to show dominance, but I am not sure, maybe the curiousity instinct. Why is killing people fun? (I am not talking about self defence or consciencious war/robbery.)
Not being critical, and meaning no offense, but in deference to the younger members here perhaps the thread title could have been more of a question than a declaration. Enjoy!