by 7500 b.c.
3000 b.c.
Chiefdoms
5500 b.c.
4000 b.c.
2500 b.c.
Widespread metal tools
4000 b.c.
2000 b.c.
2000 b.c.
or artifacts (copper
and/or bronze)
States
3700 b.c.
2000 b.c.
500 A.D.
Writing
3200 b.c.
by 1300 b.c.
A.D. 43
Widespread iron tools
900 b.c.
500 b.c.
650 b.c.
This table gives approximate dates of widespread adoption of significant developments in three Eurasian and four Native American areas. Dates for animal domestication neglect dogs, which were domesticated earlier than food-producing animals in both Eurasia and
ture surely did not provide the basis for most human calorie intake and sedentary existence in American homelands until much later than in Eurasian homelands.
As we saw in Chapters 5 and 10, only a few relatively small areas of each hemisphere acted as a "homeland" where food production first arose and from which it then spread. Those homelands were the Fertile Crescent and China in Eurasia, and the Andes and Amazonia, Mesoamerica, and the eastern United States in the Americas. The rate of spread of key developments is especially well understood for Europe, thanks to the many archaeologists at work there. As Table 13.1 summarizes for England, once food production and village living had arrived from the Fertile Crescent after a long lag (5,000 years), the subsequent lag for England's adoption of chiefdoms, states, writing, and especially metal tools was much shorter: 2,000 years for the first widespread metal tools of copper and bronze, and only 250 years for widespread iron tools. Evidently, it was much easier for one society of already sedentary farmers to "borrow" metallurgy from
HEMISPHERESCOLLIDING • 363
Native America
Andes
Amazonia
Mesoamerica Eastern U.S.
by 3000 B.C.
3000 b.c.
by 3000 b.c. 2500 b.c.
3500 b.c.
p
500 b.c. —
3100-1800 b.c.
6000 b.c.
1500 b.c. 2500 b.c.
3100-1800 b.c.
6000 b.c.
1500 b.c. 500 b.c.
by 1500 b.c.
A.D. 1
1500 b.c. 200 b.c.
A.D. 1000
—— "
—— —— –
A.D.1
300 b.c. —
—
—
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-
364' GUNS, GERMS, AND STEEL
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