look at anyone playing GTA or a god sim game where there's an evil option and you'll quickly come to the conclusion that true evil is human nature in a consequence free environment. or maybe I'm just overly cynical about humanity...
edit: as to the things people are saying regarding "evil is a concept developed by society", most things we consider evil, are considered evil because we needed to stop people doing them, so that implies that before we slapped the evil sticker on something, it was actually normal to do it...
think about it, a caveman (caveman A) finally kills an animal and another (caveman B) attempts to steal it, caveman A kills caveman B and cannibalizes his body. from a purely logic and survival based viewpoint it makes perfect sense, caveman A keeps his stuff, there is less competition for resources, assuming they are both male, less competition for a mate, and a free meal and more bones and other resources from caveman B's body
we consider murder and cannibalism evil because it is no longer a necessity, and therefore anyone else doing it is basically doing it for fun, if humanity was nearly wiped out and there were no other resources around, would you kill and eat another human if they were given the same dilemma? if you do, you survive and continue the human race, if you don't you die and the other human uses your body to survive, if neither do, humanity becomes extinct.
