This story in Nature News about societal collapse in ancient Peru is worth noting, especially for this quote by one of the main researchers:
Dramatic climactic events are always used to explain culture change in the Andes. But this is not satisfying based on what we know about human culture. It paints a picture of culture sitting there, not changing, hit by events over which they have no control. But Native Americans did not always live in harmony with their environment.
That last line provided some fodder for an interesting exchange in the comments thread of the story. I really wish Savage Minds would take up this meme some day. By happenstance, the death of this giant in anthropology is relevant to a wider discussion, which Rex duly notes over at Savage Minds:
First, LÃ©vi-Strauss taught us that culture is a force in its own right.
The question many scholars struggle with is how much of a "force" culture plays in a society's own demise--be it the Anasazi, the Angkor, or even in the widely cited case of a certain island people.