@Dosed,
I struggle with this thought all the time.
When the beginning, however you imagine it, of the earth came about, there was no perception of evil. You killed to survive, you killed to eat, and you killed for clothing, shelter, all of that business. There was no murder, there was simply necessary killing of animals. We understood how to cook and kill animals over time, and we thought nothing of it.
Now this is where creationism versus evolution comes into play. The creationist thought is generally that some holy figure from heaven came down and brought with him laws and guidelines dictating evil acts and righteous acts. A solid line between good and evil came about, but I think that the actual reason we have good and evil all developed from necessity, the mother of all invention.
Think about it: A small tribe of Neanderthals, basic hominids still running on primal instincts, stick together and form a small community. They understand that needless killing of any member of the tribe, any loss, is just a loss to the tribes effectiveness. I do not believe at all that any emotional bonds were developed at this time. If someone in the tribe was lost, or killed, all it meant was that there was one less person to help hunt, one less person to build shelters, one less person to defend against anything that might occur, and so on.
That is precisely where good and evil came about. It isn't necessary to kill a member of the tribe, so we don't. If we do kill a member of the tribe, it weakens the tribe, and therefore the killer has inconvenienced the tribe. Good and evil are not based on morality; morality wasn't quite around at that point. Good and evil are based on necessity. It's not necessary to kill a tribe member, so don't. Is it ok to kill a tribe member? Is it bad? No. There is no bad, and no good, there is only what benefits, and what debilitates.