Collapse of Complex Societies.

Presentation and question & answer.
"The collapse of complex societies of the past can inform the present on the risks of collapse. Dr. Joseph Tainter, author of the book The Collapse of Complex Societies.  2010 International Conference on Sustainability: Energy, Economy, and Environment organized by the Local Future."
Unfortunately in 7 parts on YouTube, but worth finding and watching it all.
Part one:  http://www.youtube.com/watch?v=ddmQhIiVM48