At least in Africa, part of the explanation of poverty is the enduring effect of slavery:
Slavery, according to historical accounts, played an important role in Africa’s underdevelopment. It fostered ethnic fractionalisation and undermined effective states. The largest numbers of slaves were taken from areas that were the most underdeveloped politically at the end of the 19th century and are the most ethnically fragmented today. Recent research suggests that without the slave trades, 72% of Africa’s income gap with the rest of the world would not exist today. … The countries from which the most slaves were taken (taking into account differences in country size) are today the poorest in Africa. …
An alternative explanation for the relationship is that the parts of Africa from which the largest number of slaves were taken were initially the most underdeveloped. Today, because these characteristics persist, these parts of Africa continue to be underdeveloped and poor. My research examines this alternative hypothesis by testing whether it was in fact the initially least developed parts of Africa that engaged most heavily in the slave trades. I find that the data and the historical evidence suggest that, if anything, it was the parts of Africa that were initially the most developed, not least developed, that supplied the largest number of slaves. (source)
It’s not difficult to imagine how large scale “extraction” of able bodied young people can harm an economy, even centuries after the event. The huge importance of the effect of slavery (“if the slave trades had not occurred, then … 99% of the income gap between Africa and the rest of the underdeveloped world would not exist”) should lay to rest frivolous speculation about cultural or racial causes of Africa’s predicament.