The NY Times reviews Gregory Clark's "A Farewell to Alms: A Brief Economic History of the World." It looks like an interesting read, in line with all the recent economics books that aren't full of endless equations:

"Clark argues that persistently different rates of childbearing and survival, across differently situated families, changed human nature in ways that finally allowed human beings to escape from the Malthusian trap in which they had been locked since the dawn of settled agriculture, 10,000 years before. Specifically, the families that propagated themselves were the rich, while those that died out were the poor. Over time, the 'survival of the richest' propagated within the population the traits that had allowed these people to be more economically successful in the first place: rational thought, frugality, a capacity for hard work — in short the familiar list of Calvinist, bourgeois virtues."