Economics and labor

Some interesting historical speculation by Charles C. Mann in The Real Story of Globalization.

Initially, American planters preferred to pay to import European laborers—they spoke the same language and knew European farming methods. They also cost less than slaves bought from Africa, but they were far less hardy and thus a riskier investment. In purely economic terms, the historian Philip Curtin has calculated, the diseases of the Columbian Exchange made the enslaved worker "preferable at anything up to three times the price of the European."

Did the Columbian Exchange cause chattel slavery in the Americas? No. People are moral agents who weigh many considerations. But anyone who knows how markets work will understand the pull exerted by slavery's superior profitability.