Secrets of Success

Joel Mokyr from the December 1998 issue

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Diamond, to put it bluntly, is a geographical determinist. The shape and location of continents, original flora and fauna, microbes, water, climate, topography--all are truly exogenous to history. The rest is endogenous. Geography, of course, has a terrible reputation in historical explanation. Landes, in his Wealth and Poverty, starts off by recounting how geography departments were closed around the country without a tear; he notes that "no other discipline has been so depreciated and disparaged." Simple-minded explanations that submit that "Britain had an Industrial Revolution because it had coal" have long been abandoned.

Yet before we dismiss Diamond's book as another simplistic tale, we have to face the fact that he knows his stuff inside out, to the point where any thought of using the adjective crude (traditionally preceding determinist) evaporates as we turn the pages. Diamond fires off a barrage of facts and observations based on half a dozen disciplines, from archeology to botany to linguistics. He argues that the world's population bifurcated for geographical reasons. Once the different paths were established, "Eurasia" diverged from Africa and America more and more through positive feedback effects, in which geography fed into technology and technology fed into power structures and culture, which fed back into technology and growth, until we got a world of Western economic hegemony.

Diamond emphasizes that human wealth and success depend on interaction with the environment. Economic history, in his view, is a game against nature, not primarily a social process. Production, especially in agriculture, depends on the geographical hand we have been dealt. Yet Diamond, unlike most geographers, focuses not on soil fertility and minerals but on the ability of humansto domesticate plants and animals. Unlike Sowell, he says all societies and cultures initially had similar abilities to manipulate nature, but their raw materials were different.

To exploit large animals for food, energy, or other uses, you need domesticable wild animals, something that did not exist in pre-Columbian America (where the arrival of Homo sapiens 13,000 years ago apparently led to their extinction). Such animals have to satisfy certain conditions: They must be able to breed in captivity, they must be safe around children, and so on. Diamond lists five major species of large, domesticable animal species--cows, goats, sheep, pigs, and horses--and nine minor ones, including reindeer, yaks, and llamas. Of these 14, only one was native to South America (llamas and their close cousins, alpacas) and none to North America.

Diamond argues persuasively that the hippos and giraffes of Africa, the jaguars of the Amazon, and the kangaroos of Australia were not domesticable. He says the domesticated llamas, alpacas, turkeys, and dogs of America could not pull it off either. North America's other large herbivorous mammals all turned out to be nondomesticable. Eurasia, on the other hand, was lucky enough to have the wild animals from which our cows, sheep, horses, and chickens could be bred. This gave the Europeans huge advantages not only in the development of technology (mixed farming and wheeled transport, for example) but also in resistance to infection, providing them with immunity against diseases caused by proximity to domestic animals. When Europeans traveled to other continents, the infectious diseases they carried overwhelmed the natives.

Eurasia was also lucky to have a much larger stock of plants that lent themselves to domestication. Eurasian plants were more nutritious, easier to cultivate, and more resistant to disease. Botanical wealth, says Diamond, determined agriculture, and agriculture determined everything else. Eurasia won because its supply of wild plants, which provided the gene pool for domesticated crops, was larger, richer, and better. If you think this explanation is simplistic, read the chapters on "How to Make an Almond" and "Apples and Indians."

Diamond realizes, of course, that the Americas contained a considerable number of highly nutritious crops, many of which were transplanted successfully to Eurasia after 1500. Yet he maintains that because of diverse climates and the narrow connection between North and South America, such crops did not proliferate as readily as in Eurasia. Doubts begin to emerge here: Corn and potatoes are hardy plants that grow in a wide variety of conditions, and Diamond never quite nails down the reason for their failure to spread earlier and more widely in pre-Columbian times.

Perhaps, as Diamond seems to believe, they would have, had there been more time. Had Columbus arrived a millennium or two later, North America might have been a very different society. Surprisingly, Diamond says little about the potential of the lowly potato, which merits only cursory mentions in his book even though it radically transformed the societies in which it was adopted. Such doubts notwithstanding, this is a serious, informed, and well-thought-out argument. If in the end we are not wholly convinced, thinking of how to refute Diamond will make us wiser.

How much of the performance of non-Europeans was constrained by their environment, and how much was their own making? In Diamond's view, the answers are "all" and "none." But this is by no means clear. For example, Diamond says one of the disadvantages encountered by the indigenous people of what is now the eastern United States was a lack of wild plants that could be turned into crops. Yet he concedes that some native species might have done nicely. He describes sumpweed, with 32 percent protein, as "a nutritionist's ultimate dream." He explains that the flower did not make it to the rank of corn, potatoes, and rye because it causes hayfever, smells bad, and can cause skin irritation. Are we sure that these vices could not have been bred out of sumpweed, just because they were not? All domesticated plants originally had undesirable characteristics, but through deliberate and lucky selection mechanisms they eventually got over them. Wheat, rye, and maize, which feed much of the world's population, all had humble beginnings.

To be fair, Diamond's argument is not entirely ex post. He points out that our ability to improve plants depended largely on whether the code for certain characteristics was carried by more than one gene. People could select for a particular trait as long as it was caused by one or very few genes; if it was controlled by many genes, breeding specimens that displayed the trait would be unlikely to fix it in the population. Diamond offers a few examples, but he does not persuade me that this problem was especially pronounced in the societies he identifies as geographically challenged.

There is a similar weakness in Diamond's view of technology. In a chapter cleverly named "Necessity's Mother," he notes the many links between geographical constraints and technical options. Why would a society produce wheels if it had no horses or oxen to pull them? Wheelbarrows and rickshaws might have been an option, but maybe draft animals came first. Not all questions can be answered this way: Some indigenous populations in America might have built seaworthy ships, or managed to develop a technology we cannot imagine today. If they did not, is this because they tried and failed, or because they never tried?

Diamond offers two reasons to believe that links between geography and technological progress may be significant. One is that geography constrains mobility of knowledge. Assume, somewhat implausibly, that the idea of a wheelbarrow occurred to just one person in history, but that it spread to people seeing their neighbors use one. If this happened in Central Asia, it may well have reached China, France, and Yemen within a few centuries, but before 1500 it would never have gotten to America or Australia. And Diamond notes that agricultural technology diffuses more easily from east to west than from north to south, since changing longitude has a stronger effect on climate and seasonality than changing latitude--giving Eurasia an advantage over America and Africa.

Diamond also resurrects the late Julian Simon's argument that technological success often depends on population density and the ability of a society to produce a surplus beyond subsistence, so that there are resources available for tinkering and experimenting. Maximum population density was largely a function of the environment's ability to feed people. Writing, for instance, required large and dense settlements with complex hierarchical institutions, much different from hunting and gathering tribes.

The notion that much of economic history is a game against nature, in which people form certain views about its regularities and use these to manipulate their environment and improve their material conditions, is a powerful one. Diamond's insight is that nature differs from place to place and that certain environments are easier to manipulate than others.

The economic historian must addtwo qualifications to this. First, environments can be manipulated or abandoned. While Diamond describes in detail prehistoric population movements (which he deduces from linguistic evidence), he does not realize that he tells the story of regions, not necessarily of people living there, who always had the option of moving to a more generous and flexible area. Second, it could be argued that much technology emerges precisely because the environment is not generous and requires hard work and ingenuity. It is here that Sowell's "cultural capital" comes in, directing us to another important set of variables. The difference between the two approaches is that in Diamond's account culture itself is determined by location: Geography truly is destiny.

How can we be sure? We cannot. When all is said and done, the overdetermined nature of the issue remains: There are many explanations for the observed gaps in income and economic success, and they all make sense; they all are consistent with the evidence. Our models of history, however, are still unable to rank them by importance or assign weights to them. Is culture really determined by geography, as Diamond thinks, or is technological success above all a rebellion against the dictates of the environment? If everything in global history is interrelated with everything else, who can blame our students for being bewildered? After all, Fermat's Last Theorem took three centuries to prove, and this problem is a lot harder.