Jared Diamond

Jared Diamond, the ecologist and evolutionary biologist whose account links geography to the origins of intercontinental inequality, supplies an influential explanation for why farming and technological development began earlier in some regions than in others. The book recognizes the force of that argument while drawing a boundary around it: differences in domesticated species may help explain distant historical divergence, but they cannot account for the modern gulf in incomes, the uneven spread of industrial technology, or dramatic disparities within the same continent.## The geographical argument Diamond’s explanation begins with the unequal distribution of plants and animals that humans could domesticate. In the Fertile Crescent, in what is now the Middle East, many species were suitable for domestication; in the Americas, fewer were. Where domestication was possible, farming became attractive earlier than a hunter-gatherer way of life. The argument makes geography consequential through a chain of social changes: farming supported denser populations, which in turn allowed greater labor specialization, trade, urbanization, and political development.

For Diamond, the effects did not stop at the emergence of settled agriculture. Societies in which farming dominated, he argues, experienced technological innovation more rapidly. Unequal natural endowments therefore produced different intensities of farming, and those differences helped set continents on divergent paths of technological change and prosperity. The book presents this as a powerful approach to the puzzle Diamond addresses, rather than dismissing geography as irrelevant.

The explanation also includes the movement of ideas and crops across landmasses. Following the historian William McNeill, Diamond argues that Eurasia’s east–west orientation enabled crops, animals, and innovations to travel from the Fertile Crescent into Western Europe. By contrast, the north–south orientation of the Americas helped prevent writing systems developed in Mexico from spreading to the Andes or North America. In this account, geography shapes not only what can be domesticated but also how readily the resulting knowledge travels.## The limits of an ancient advantage The book tests the argument against the gap between Spain and Peru. Diamond’s account can help explain why Spain, with access to wheat, barley, and horses, had advantages over the Inca Empire. But at the time of the Spanish conquest, the difference in average income was probably less than twofold. If exposure to the species and technologies that the Incas had not developed themselves were enough to explain lasting divergence, the argument would suggest that Peru should have approached Spanish living standards once those resources and technologies became available.

The opposite occurred. In the nineteenth and twentieth centuries, the income gap between Spain and Peru widened; today, the average Spaniard is more than six times richer than the average Peruvian. The book connects this later divergence not to unequal potential for animal and plant domestication, or to intrinsic differences in agricultural productivity, but to the uneven spread of modern industrial technologies.

Spain adopted steam power, railroads, electricity, mechanization, and factory production, albeit with a lag. Peru did not adopt these technologies, or did so slowly and imperfectly. The resulting gap persists, while newer technologies—particularly information technology—continue to fuel growth in many developed and some rapidly developing countries. Diamond’s account, the book argues, does not explain why these crucial technologies have failed to diffuse in ways that equalize incomes. The contrast between the two sides of the border at Nogales sharpens that challenge: they belong to one divided city, yet the northern half is much richer than its twin to the south, although both shared a civilization five hundred years ago.

The contrast also exposes the limits of explaining modern inequality through continental geography. In 1532, the civilizations of the Aztecs and Incas were more prosperous than the societies in areas that later became the United States and Canada. North America’s later prosperity followed its enthusiastic adoption of the Industrial Revolution’s technologies: its population became educated and railways spread across the Great Plains, unlike in South America. The book argues that geography cannot account for this reversal, especially when the geographic endowments, if anything, favored South America.## Inequality within continents Diamond’s framework is directed chiefly at differences between continents; the book argues that it is less equipped to explain disparities within them, which are essential to understanding modern inequality. Eurasia’s orientation may help explain how England benefited from innovations originating in the Middle East without having to reinvent them. It does not explain why the Industrial Revolution happened in England rather than Moldova. Nor does a favorable combination of plants, animals, and continental orientation explain why many of the world’s poor people live in China and India, both of which benefited from rich suites of domesticable species and from Eurasia’s geography.

The distribution of species used in Diamond’s account makes the problem visible. The wild ancestors of modern pigs and cows were widely distributed across Eurasia and even North Africa. Wild rice, the ancestor of Asian cultivated rice, was widespread across South and Southeast Asia. The ancestors of wheat and barley were distributed along a long arc from the Levant through Iran into Afghanistan and the Central Asian countries of Turkmenistan, Tajikistan, and Kyrgyzstan. Because these ancestral species were present across much of Eurasia, their distribution cannot explain why prosperity varies so sharply within the continent.

The same difficulty appears in Africa. The Sahara Desert obstructed the movement of goods and ideas from the north into sub-Saharan Africa, but the barrier was not insurmountable: the Portuguese and then other Europeans sailed around the coast. Knowledge gaps were eliminated when income differences were still small compared with those of today. Africa did not subsequently catch up with Europe; the income gap instead became much larger. Geographic separation alone cannot explain that later divergence.## Geography, institutions, and reversals The book places Diamond’s argument within a broader challenge to explanations that treat geography as a lasting, sufficient cause of prosperity or poverty. The geography of the Americas remained the same, yet the hierarchy of prosperity changed: before 1492, civilizations in Mexico’s central valley, Central America, and the Andes had higher living standards and superior technology than North America or places such as Argentina and Chile. The subsequent reversal, the book argues, followed the institutions European colonists imposed, not a change in the land.

The Middle East offers another historical reversal. It led the world in the Neolithic Revolution; the first towns developed in what is now Iraq, and iron was first smelted in what is now Turkey. The region remained technologically dynamic as late as the Middle Ages. Its later poverty, the book argues, cannot be attributed to an unchanging geography that had previously supported early agriculture, urban life, and technological advances. Instead, it connects that outcome to the expansion and consolidation of the Ottoman Empire and to the institutional legacy of Ottoman rule.

Diamond’s argument thus serves both as a serious account of how ecological endowments can shape the early development of societies and as a foil for examining modern inequality. The book does not deny that geography influenced the conditions under which farming and knowledge spread. It argues that those conditions cannot explain why industrial technology reached some societies and not others, why income gaps widened after knowledge barriers had been overcome, or why neighboring regions and countries with broadly shared geographic contexts followed sharply different paths. To account for those outcomes, the analysis turns from the distribution of useful species to the institutions that shaped technological adoption and prosperity.