Guns, Germs & Steel

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600 b.c. —

the Americas. Chiefdoms are inferred from archaeological evidence, such as ranked burials, architecture, and settlement patterns. The table greatly simplifies a complex mass of historical facts: see the text for some of the many important caveats.
another such society than for nomadic hunter-gatherers to 'borrow' food production from sedentary farmers (or to be replaced by the farmers).
why were the trajectories of all key developments shifted to later dates in the Americas than in Eurasia? Four groups of reasons suggest themselves: the later start, more limited suite of wild animals and plants available for domestication, greater barriers to diffusion, and possibly smaller or more isolated areas of dense human populations in the Americas than in Eurasia.
As for Eurasia's head start, humans have occupied Eurasia for about a million years, far longer than they have lived in the Americas. According to the archaeological evidence discussed in Chapter 1, humans entered the Americas at Alaska only around 12,000 b.c., spread south of the Canadian ice sheets as Clovis hunters a few centuries before 11,000 b.c., and reached the southern tip of South America by 10,000 b.c. Even if the dis-

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puted claims of older human occupation sites in the Americas prove valid, those postulated pre-Clovis inhabitants remained for unknown reasons very sparsely distributed and did not launch a Pleistocene proliferation of hunter-gatherer societies with expanding populations, technology, and art as in the Old World. Food production was already arising in the Fertile Crescent only 1,500 years after the time when Clovis-derived hunter-gatherers were just reaching southern South America.
Several possible consequences of that Eurasian head start deserve consideration. First, could it have taken a long time after 11,000 b.c. for the Americas to fill up with people? When one works out the likely numbers involved, one finds that this effect would make only a trivial contribution to the Americas' 5,000-year lag in food-producing villages. The calculations given in Chapter 1 tell us that even if a mere 100 pioneering Native' Americans had crossed the Canadian border into the lower United States and increased at a rate of only 1 percent per year, they would have saturated the Americas with hunter-gatherers within 1,000 years. Spreading south at a mere one mile per month, those pioneers would have reached the southern tip of South America only 700 years after crossing the Canadian border. Those postulated rates of spread and of population increase are very low compared with actual known rates for peoples occupying previously uninhabited or sparsely inhabited lands. Hence the Americas were probably fully occupied by hunter-gatherers within a few centuries of the arrival of the first colonists.
Second, could a large part of the 5,000-year lag have represented the time that the first Americans required to become familiar with the new local plant species, animal species, and rock sources that they encountered? If we can again reason by analogy with New Guinean and Polynesian hunter-gatherers and farmers occupying previously unfamiliar environments—such as Maori colonists of New Zealand or Tudawhe colonists of New Guinea's Karimui Basin—the colonists probably discovered the best rock sources and learned to distinguish useful from poisonous wild plants and animals in much less than a century.
Third, what about Eurasians' head start in developing locally appropriate technology? The early farmers of the Fertile Crescent and China were heirs to the technology that behaviorially modern Homo sapiens had been developing to exploit local resources in those areas for tens of thousands of years. For instance, the stone sickles, underground storage pits, and other technology that hunter-gatherers of the Fertile Crescent had

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been evolving to utilize wild cereals were available to the first cereal farmers of the Fertile Crescent. In contrast, the first settlers of the Americas arrived in Alaska with equipment appropriate to the Siberian Arctic tundra. They had to invent for themselves the equipment suitable to each new habitat they encountered. That technology lag may have contributed significantly to the delay in Native American developments.
An even more obvious factor behind the delay was the wild animals and plants available for domestication. As I discussed in Chapter 6, when hunter-gatherers adopt food production, it is not because they foresee the potential benefits awaiting their remote descendants but because incipient food production begins to offer advantages over the hunter-gatherer lifestyle. Early food production was less competitive with hunting-gathering in the Americas than in the Fertile Crescent or China, partly owing to the Americas' virtual lack of domesticable wild mammals. Hence early American farmers remained dependent on wild animals for animal protein and necessarily remained part-time hunter-gatherers, whereas in both the Fertile Crescent and China animal domestication followed plant domestication very closely in time to create a food producing package that quickly won out over hunting-gathering. In addition, Eurasian domestic animals made Eurasian agriculture itself more competitive by providing fertilizer, and eventually by drawing plows.
Features of American wild plants also contributed to the lesser competitiveness of Native American food production. That conclusion is clearest for the eastern United States, where less than a dozen crops were domesticated, including small-seeded grains but no large-seeded grains, pulses, fiber crops, or cultivated fruit or nut trees. It is also clear for Mesoameri-ca's staple grain of corn, which spread to become a dominant crop elsewhere in the Americas as well. Whereas the Fertile Crescent's wild wheat and barley evolved into crops with minimal changes and within a few centuries, wild teosinte may have required several thousand years to evolve into corn, having to undergo drastic changes in its reproductive biology and energy allocation to seed production, loss of the seed's rock-hard casings, and an enormous increase in cob size.
As a result, even if one accepts the recently postulated later dates for the onset of Native American plant domestication, about 1,500 or 2,000 years would have elapsed between that onset (about 3000-2500 b.c.) and widespread year-round villages (1800-500 b.c.) in Mesoamerica, the inland Andes, and the eastern United States. Native American farming

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served for a long time just as a small supplement to food acquisition by hunting-gathering, and supported only a sparse population. If one accepts the traditional, earlier dates for the onset of American plant domestication, then 5,000 years instead of 1,500 or 2,000 years elapsed before food production supported villages. In contrast, villages were closely associated in time with the rise of food production in much of Eurasia. (The hunter-gatherer lifestyle itself was sufficiently productive to support villages even before the adoption of agriculture in parts of both hemispheres, such as Japan and the Fertile Crescent in the Old World, and coastal Ecuador and Amazonia in the New World.) The limitations imposed by locally available domesticates in the New World are well illustrated by the transformations of Native American societies themselves when other crops or animals arrived, whether from elsewhere in the Americas or from Eurasia. Examples include the effects of corn's arrival in the eastern United States and Amazonia, the llama's adoption in the northern Andes after its domestication to the south, and the horse's appearance in many parts of North and South America.
In addition to Eurasia's head start and wild animal and plant species, developments in Eurasia were also accelerated by the easier diffusion of animals, plants, ideas, technology, and people in Eurasia than in the Americas, as a result of several sets of geographic and ecological factors. Eurasia's east-west major axis, unlike the Americas' north-south major axis, permitted diffusion without change in latitude and associated environmental variables. In contrast to Eurasia's consistent east-west breadth, the New