The general conclusion that colonialism was bad for growth has been oft-studied. Nathan Nunn, however, gives evidence that the 19th century slave trades – trans-Atlantic, Arab and Indian Ocean – have similarly deleterious effects on modern economic growth. He uses a comprehensive dataset on slave origins, using ethnic names to link slave origin to modern national boundaries. His regressions show a clear relationship between the origin of slaves and poor late 20th century growth, even after attempting to control for colonial influence, weather, etc. He rejects the conclusion that poorly developed areas before the slave trade were the most likely to export slaves – rather, the opposite is true, since wealthier areas had preexisting trade relations with Europe and Arabia, and had a high enough population density to support slave export. The precise causal method of high slavery leading to poor modern development is less clear, but there is some evidence that, first, the slave trade caused ethnic friction which has continued to the present, and second, that the slave trade overturned the preexisting state apparatus in highly developed areas of Africa (say, Kongo in the 15th century); it is well known in the growth literature that nations with higher levels of “experience” in operating as a functional state are more likely to see higher rates of growth in the modern period, and the slave trade may have interrupted this link in some areas. It goes without saying that any statistical evidence brought to bear on these questions in limited both by small sample size and by limited data availability, so the link between slavery and modern growth should be seen perhaps as persuasive rather than proven.
“The Long-Term Effects of African Slave Trades,” Nunn, 2008