History is not often thought of as a science, but it can be if it uses the “comparative method.” Jared Diamond, professor of geography at the University of California, Los Angeles, and James A. Robinson, professor of government at Harvard University, employ the method effectively in the new book they have co-edited, Natural Experiments of History (Harvard University Press, 2010). In a timely study comparing Haiti with the Dominican Republic, for example, Diamond demonstrates that although both countries inhabit the same island, Hispaniola, because of geopolitical differences one ended up dirt poor while the other flourished.
Christopher Columbus’s brother Bartolomeo colonized Hispaniola in 1496 for Spain, establishing the capital at Santo Domingo on the eastern side of the island. Two centuries later, during tensions between France and Spain, the Treaty of Ryswick in 1697 granted France dominion over the western half of the island. Because France was richer than Spain at this time and slavery was an integral part of its economy, it turned western Hispaniola into a center of slave trade with staggering differences in population: about 500,000 slaves in the western side of the island as compared with only 15,000 to 30,000 slaves in the eastern side.