world, but then started a long slide. The Soviet Union is an even more noteworthy example, growing rapidly between 1930 and 1970, but subsequently experiencing a rapid collapse.
What explains these major differences in poverty and prosperity and the patterns of growth? Why did Western European nations and their colonial offshoots filled with European settlers start growing in the nineteenth century, scarcely looking back? What explains the persistent ranking of inequality within the Americas? Why have sub-Saharan African and Middle Eastern nations failed to achieve the type of economic growth seen in Western Europe, while much of East Asia has experienced breakneck rates of economic growth?
One might think that the fact that world inequality is so huge and consequential and has such sharply drawn patterns would mean that it would have a well-accepted explanation. Not so. Most hypotheses that social scientists have proposed for the origins of poverty and prosperity just don’t work and fail to convincingly explain the lay of the land.
T HE G EOGRAPHY H YPOTHESIS
One widely accepted theory of the causes of world inequality is the geography hypothesis, which claims that the great divide between rich and poor countries is created by geographical differences. Many poor countries, such as those of Africa, Central America, and South Asia, are between the tropics of Cancer and Capricorn. Rich nations,in contrast, tend to be in temperate latitudes. This geographic concentration of poverty and prosperity gives a superficial appeal to the geography hypothesis, which is the starting point of the theories and views of many social scientists and pundits alike. But this doesn’t make it any less wrong.
As early as the late eighteenth century, the great French political philosopher Montesquieu noted the geographic concentration of prosperity and poverty, and proposed an explanation for it. He argued that people in tropical climates tended to be lazy and to lack inquisitiveness. As a consequence, they didn’t work hard and were not innovative, and this was the reason why they were poor. Montesquieu also speculated that lazy people tended to be ruled by despots, suggesting that a tropical location could explain not just poverty but also some of the political phenomena associated with economic failure, such as dictatorship.
The theory that hot countries are intrinsically poor, though contradicted by the recent rapid economic advance of countries such as Singapore, Malaysia, and Botswana, is still forcefully advocated by some, such as the economist Jeffrey Sachs. The modern version of this view emphasizes not the direct effects of climate on work effort or thought processes, but two additional arguments: first, that tropical diseases, particularly malaria, have very adverse consequences for health and therefore labor productivity; and second, that tropical soils do not allow for productive agriculture. The conclusion, though, is the same: temperate climates have a relative advantage over tropical and semitropical areas.
World inequality, however, cannot be explained by climate or diseases, or any version of the geography hypothesis. Just think of Nogales. What separates the two parts is not climate, geography, or disease environment, but the U.S.-Mexico border.
If the geography hypothesis cannot explain differences between the north and south of Nogales, or North and South Korea, or those between East and West Germany before the fall of the Berlin Wall, could it still be a useful theory for explaining differences between North and South America? Between Europe and Africa? Simply, no.
History illustrates that there is no simple or enduring connectionbetween climate or geography and economic success. For instance, it is not true that the tropics have always been poorer than temperate latitudes. As we saw in the last chapter, at the time of the conquest of the Americas by Columbus, the areas south of the Tropic of Cancer and north of the