Linkage

Failure to replicate Spolaore and Wacziarg's well-known paper on genetic distance. Well, not failure to replicate but failure to be robust to be different controls. Perhaps this is just the old problem of "what to do with cross-country correlations?": it is hard to make claims about causality from such regressions, and yet we want to know something about the differences between countries. A tricky problem which I cannot solve, and that is one reason I try to work at the micro level! Spolaore and Wacziarg reply beneath the article.