The Economist (Mar.30) paraphrases a paper on “The Colonial Origins of Comparative Development” (by Daron Acemoglu, Simon Johnson and James A. Robinson, American Economic Review Dec.2001):

The harder it was for Europeans to settle a region, the greater the culture of exploitation created: finding a foreign land hard to settle, colonists preferred to exploit the natives from afar, rather than to build wealth. By looking at mortality rates of pioneering soldiers, sailors and bishops, the authors found a strong correlation between colonists’ death rates and modern measures of political risk and expropriation. Indeed, the authors estimate that these shortcomings account for nearly all the income gap between Africa and rich countries.