Human Nature Rears its Ugly Head

We started studying the Cold war in history class today. A girl in the class asked why everybody hates Communism. This got me thinking, as so many seemingly insignificant things do.

The original idea of Communism was in fact a fairly intelligent idea. No classes, no rich or poor, no one better or worse off than anyone else. Everyone has what they need. The thing is, every time a nation has attempted Communism, someone fucked it up. There's always somone who decides to take advantage of his comrades. The Communist system is possibly the easiest to control through bribery and graft. In a society where everyone exists at the same level, the slightse increase in money or property (if they exist) can make a man feel superior.

Anyway, some friends and I were talking about this at lunch, and we were wondering why every attmept at Communism has failed or is failing. Eventually we decided that they were ruined by greed, and that true Communism can never be achieved because greed is part of human nature.

Now, I am not advocating Communism here. I am wondering why greed is part of human nature. Although you probably could find someone who is inherently not greedy, it would be the longest and hardest search for anything since the Holy Grail. What survival purpose does greed serve? Despite our "civilization" and "progress," I firmly belive that everything we do is somehow related to our survival. It may not be in an obvious manner, like running from the man with the gun. It may be something that truly doesn't matter, but subconciously we imagine that if we don't do it we will die.

So I'm looking for input. Here's the question: Why do so many things that hurt ourselves and others seem to be inherent qualities of the human race?

Any idea from any source is welcome.