continents.
Though Diamond’s thesis is a powerful approach to the
puzzle on which he focuses, it cannot be extended to
explain modern world inequality. For example, Diamond
argues that the Spanish were able to dominate the
civilizations of the Americas because of their longer history
of farming and consequent superior technology. But we
now need to explain why the Mexicans and Peruvians
inhabiting the former lands of the Aztecs and Incas are
poor. While having access to wheat, barley, and horses
might have made the Spanish richer than the Incas, the gap
in incomes between the two was not very large. The
average income of a Spaniard was probably less than
double that of a citizen of the Inca Empire. Diamond’s
thesis implies that once the Incas had been exposed to all
the species and resulting technologies that they had not
been able to develop themselves, they ought quickly to
have attained the living standards of the Spanish. Yet
nothing of the sort happened. On the contrary, in the
nineteenth and twentieth centuries, a much larger gap in
incomes between Spain and Peru emerged. Today the
average Spaniard is more than six times richer than the
average Peruvian. This gap in incomes is closely
connected to the uneven dissemination of modern industrial
technologies, but this has little to do either with the potential
for animal and plant domestication or with intrinsic
agricultural productivity differences between Spain and
Peru.
While Spain, albeit with a lag, adopted the technologies
of steam power, railroads, electricity, mechanization, and
factory production, Peru did not, or at best did so very
slowly and imperfectly. This technological gap persists
today and reproduces itself on a bigger scale as new
technologies, in particular those related to information
technology, fuel further growth in many developed and
some rapidly developing nations. Diamond’s thesis does
not tell us why these crucial technologies are not diffusing
and equalizing incomes across the world and does not
explain why the northern half of Nogales is so much richer
than its twin just to the south of the fence, even though both
were part of the same civilization five hundred years ago.
The story of Nogales highlights another major problem in