Highly recommended: Daron Acemoglu, Simon Johnson, and James Robinson, "Institutions as the Fundamental Cause of Long-Run Growth" (NBER Working Paper 10481, May 2004). I would quarrel with their proxy for economic prosperity circa 1500, population density--is a family with five children, all high school dropouts, more or less "prosperous" than a family with only two children, but both college graduates?--but it is terrifically engaging and impressive. The $64,000 question in economics is why are some countries so rich while other countries are so poor, and Professors Acemoglu, Johnson, and Robinson seem to have a good bit of the answer.