I can't upload files to the discussion any more, so I will upload it in the comment field below.  - DG

Feast, Famine, and the Rise and Fall of Civilizations
Just how important is food to the stability of a society? We'll examine the Romans and Mayans, modern challenges in the United States and China and more this hour with agricultural expert Evan D. G. Fraser, co-author of the new book "Empires of Food: Feast, Famine, and the Rise and Fall of Civilizations" (Free Press, 2010).