What is the difference between this and that human?

What causes masses to kill each other?
What is the reason that one human states that he/she is better than another one?
What causes this thinking?

Humans are one species but that does not stop them from killing and hating each other, brutality in any form appears in all the 'developed' areas of the world while most 'primitive' tribes do not hate other tribes or consider someone who looks different then they do as a threat. What makes us so much less capable of dealing with other human beings?
The main difference between our picture and that of the 'primitive' tribe is that they (the tribe) do not see other humans as something different but as humans. We on the other hand see someone with a different language then ours or with a different skin color as different and thus as an unknown. The unknown is something that the human is the most scared of, humans have tried to rid themselves from this fear by eliminating unknowns, something that has only limited success. But than the humans found another way of destroying unknowns which is destroying the object that can not be explained, the argument then would be that when the unknown is destroyed than the unknown can not endanger the humans that destroyed it. This approach has caused a great deal of destruction and death, is this why we named our own races current development state 'Homo Sapiens Sapiens' which means Whise Whise Man. What would thought of a man living on top of a mountain entirely alone stating that he was a Whise Whise Man would he be taken serioulsy or rather be considered crazy and sent to asylum. Is our race ready for the asylum?