Annalee Newitz has a fascinating article at IO9 on early neolithic societies: How Farming Almost Destroyed Ancient Human Civilization.

Roughly 9,000 years ago, humans had mastered farming to the point where food was plentiful. Populations boomed, and people began moving into large settlements full of thousands of people. And then, abruptly, these proto-cities were abandoned for millennia. It’s one of the greatest mysteries of early human civilization.

…The problem is that people in Neolithic mega-villages had inherited a system of social organization and spirituality from their nomadic forebears. Because nomadic life requires everyone in the group to share resources to survive, these groups would develop rituals and customs that reinforced a very flat social structure. Certainly there would be families that had more prominent positions in a hunter-gatherer group or small village, but if they ever started hoarding resources too much that would be bad for the entire group…