Why is it that some countries today are very rich while others are very poor, whereas in 1800 all countries were comparatively poor? The explanation of what happened, according to Gregory Clark in A Farewell to Alms: A Brief Economic History of the World, is that the wealthy countries managed to increase productivity per capita through innovations. However, this does not explain why the productivity increases started when they did, or why some countries have benefitted greatly while others have not.
Clark’s explanation for why the productivity increases started in England is the seemingly bizarre one that at the applicable time England’s upper classes had higher birth rates than the lower classes, and the upper class skills such as literacy and a disciplined approach to work were thereby transmitted down through the society. His explanation for the current divergence between rich and poor countries is that workers in poorer countries are less productive.
The book is essentially a detailed examination of the history of the Industrial Revolution in England, with references to the current great divergence between rich and poor countries little more than an afterthought. The questions posed are very interesting, but I found the answers largely unconvincing. If workers in poor countries are less productive, why do they suddenly become more productive when they migrate to richer countries?