Slavery and comparative advantage

From Mapping Human History: Genes, Race, and Our Common Origins by Steve Olson. Page 57.

A fascinating yet troubling hypothesis. Comparative advantage as the root cause of slavery in an increasingly productive and technology fueled world. The argument makes sense but still is uncomfortable. There is not much daylight between selling a human because they are bounty from conquest versus selling a human because they are worth more elsewhere than they can produce locally but for some reason the latter feels in some unfathomable way more inhumane.

In the middle Ages the geographic origins of slaves in the western world began to change. The number of slaves from Europe and Asia gradually fell, while the number from Africa grew. By 1700, Africa was the world's primary source of slaves.

Scholars have cited many reasons for Africa's rise as a slave producer. Tropical climates and poor soils in Africa limited agricultural productivity, so the overall economic return from selling a young male into slavery was greater than if that man became a farmer. Africans captured and sold slaves in exchange for manufactured goods, which delayed the continent's economic development and further depressed the value of labor within Africa. The rise of sugar production in the New World created a need for huge numbers of agricultural laborers, and Africans were more resistant to the diseases of tropical sugar plantations than were people from other parts of the world. The slave trade was highly profitable to those who provided, transported, and used slaves, and the continents political fragmentation made it difficult for African leaders to stop the practice. All of these factors tended to reinforce one another. Once Africa became established as the leading exporter of slaves, the trade gained a momentum that was very difficult to reverse.