Re: what makes humans evil ?
Following things are true about you for sure.
You are over confident about your arguments and think that people would take it same as you think of that. Whereas fact is
You do not do you own research rather overwhelmed by scientific shield; otherwise you might have come up with some technical details.
Biological urge and natural instinct changes to evolutionary psychology now 
If you have some technical point from that book related to my question do discuss here. I don’t want to waste rest of my life in search of a scientific proof of that.
You must know the definition of evolution:
1.The process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the the history of the earth.
2.The gradual development of something, esp. from a simple to a more complex form. Even oxford dictionary tells, it is thought not fact.
However see, I asked you what makes mother love her child. You told it is result of years of evolution.
See, in the light of definition of evolution, what my question has to do with evolution???
if it has, so answer my question how this natural instinct evolved from basic to complex level, what was the basic level?
If you don’t give to-the-point direction or answer to my question, I would take your argument as proof of evolution of loving offerings is, which is, “Taking caring of off spring is intrinsic in animals”. So finish it.
No, it is not an arbitrary point; I took it from your comments. Your comments were rather contradictory. You said, you are selfless person and to be caring and giving is self serving attitude. Can you be selfless and self serving at the same time. Why would you care about someone for nothing in return?
You are caring because you want others be caring toward you. That’s all for yourself nothing is about selflessness here.
That means every act in this world is subjective unless it is proved in scientific lab. Even right and wrong are subjective. An act is subjective just because two different people had different take on that?
Almost everything in this world is subjective to your interpretation, how funny this notion is.
Spy agencies of differnt counteries task their forces to disturb/disorder the law and order situation of enemy country even by killing innocent people. If you say that this evil is also subjective, i would say there is something wrong with you.