The reversal of fortune thesis reconsidered

Acemoglu, Johnson, and Robinson have claimed that the world income distribution underwent a 'Reversal of Fortune' from 1500 to the present, whereby formerly rich countries in what is now the developing world became poor while poor ones grew rich. We question their analysis with regard to both of their proxies for pre-modern income, namely urbanisation and population density. More specifically, an alternative measure of urbanisation with more observations generates a positive (but not significant) correlation between pre-modern and contemporary income, while a better measure of population density on arable land no longer produces a robust relationship.