THE LARGEST POPULATION REPLACEMENT OF THE LAST 13,000 years has been the one resulting from the recent collision between Old World and New World societies. Its most dramatic and decisive moment, as we saw in Chapter 3, occurred when Pizarro’s tiny army of Spaniards captured the Inca emperor Atahuallpa, absolute ruler of the largest, richest, most populous, and administratively and technologically most advanced Native American state. Atahuallpa’s capture symbolizes the European conquest of the Americas, because the same mix of proximate factors that caused it was also responsible for European conquests of other Native American societies. Let us now return to that collision of hemispheres, applying what we have learned since Chapter 3. The basic question to be answered is: why did Europeans reach and conquer the lands of Native Americans, instead of vice versa? Our starting point will be a comparison of Eurasian and Native American societies as of A.D. 1492, the year of Columbus’s “discovery” of the Americas.

OUR COMPARISON BEGINS with food production, a major determinant of local population size and societal complexity—hence an ultimate factor behind the conquest. The most glaring difference between American and Eurasian food production involved big domestic mammal species. In Chapter 9 we encountered Eurasia’s 13 species, which became its chief source of animal protein (meat and milk), wool, and hides, its main mode of land transport of people and goods, its indispensable vehicles of warfare, and (by drawing plows and providing manure) a big enhancer of crop production. Until waterwheels and windmills began to replace Eurasia’s mammals in medieval times, they were also the major source of its “industrial” power beyond human muscle power—for example, for turning grindstones and operating water lifts. In contrast, the Americas had only one species of big domestic mammal, the llama / alpaca, confined to a small area of the Andes and the adjacent Peruvian coast. While it was used for meat, wool, hides, and goods transport, it never yielded milk for human consumption, never bore a rider, never pulled a cart or a plow, and never served as a power source or vehicle of warfare.

That’s an enormous set of differences between Eurasian and Native American societies—due largely to the Late Pleistocene extinction (extermination?) of most of North and South America’s former big wild mammal species. If it had not been for those extinctions, modern history might have taken a different course. When Cortés and his bedraggled adventurers landed on the Mexican coast in 1519, they might have been driven into the sea by thousands of Aztec cavalry mounted on domesticated native American horses. Instead of the Aztecs’ dying of smallpox, the Spaniards might have been wiped out by American germs transmitted by disease-resistant Aztecs. American civilizations resting on animal power might have been sending their own conquistadores to ravage Europe. But those hypothetical outcomes were foreclosed by mammal extinctions thousands of years earlier.

Those extinctions left Eurasia with many more wild candidates for domestication than the Americas offered. Most candidates disqualify themselves as potential domesticates for any of half a dozen reasons. Hence Eurasia ended up with its 13 species of big domestic mammals and the Americas with just its one very local species. Both hemispheres also had domesticated species of birds and small mammals—the turkey, guinea pig, and Muscovy duck very locally and the dog more widely in the Americas; chickens, geese, ducks, cats, dogs, rabbits, honeybees, silkworms, and some others in Eurasia. But the significance of all those species of small domestic animals was trivial compared with that of the big ones.

Eurasia and the Americas also differed with respect to plant food production, though the disparity here was less marked than for animal food production. In 1492 agriculture was widespread in Eurasia. Among the few Eurasian hunter-gatherers lacking both crops and domestic animals were the Ainu of northern Japan, Siberian societies without reindeer, and small hunter-gatherer groups scattered through the forests of India and tropical Southeast Asia and trading with neighboring farmers. Some other Eurasian societies, notably the Central Asian pastoralists and the reindeer-herding Lapps and Samoyeds of the Arctic, had domestic animals but little or no agriculture. Virtually all other Eurasian societies engaged in agriculture as well as in herding animals.

Agriculture was also widespread in the Americas, but hunter-gatherers occupied a larger fraction of the Americas’ area than of Eurasia’s. Those regions of the Americas without food production included all of northern North America and southern South America, the Canadian Great Plains, and all of western North America except for small areas of the U.S. Southwest that supported irrigation agriculture. It is striking that the areas of Native America without food production included what today, after Europeans’ arrival, are some of the most productive farmlands and pastures of both North and South America: the Pacific states of the United States, Canada’s wheat belt, the pampas of Argentina, and the Mediterranean zone of Chile. The former absence of food production in these lands was due entirely to their local paucity of domesticable wild animals and plants, and to geographic and ecological barriers that prevented the crops and the few domestic animal species of other parts of the Americas from arriving. Those lands became productive not only for European settlers but also, in some cases, for Native Americans, as soon as Europeans introduced suitable domestic animals and crops. For instance, Native American societies became renowned for their mastery of horses, and in some cases of cattle and sheepherding, in parts of the Great Plains, the western United States, and the Argentine pampas. Those mounted plains warriors and Navajo sheepherders and weavers now figure prominently in white Americans’ image of American Indians, but the basis for that image was created only after 1492. These examples demonstrate that the sole missing ingredients required to sustain food production in large areas of the Americas were domestic animals and crops themselves.

In those parts of the Americas that did support Native American agriculture, it was constrained by five major disadvantages vis-à-vis Eurasian agriculture: widespread dependence on protein-poor corn, instead of Eurasia’s diverse and protein-rich cereals; hand planting of individual seeds, instead of broadcast sowing; tilling by hand instead of plowing by animals, which enables one person to cultivate a much larger area, and which also permits cultivation of some fertile but tough soils and sods that are difficult to till by hand (such as those of the North American Great Plains); lack of animal manuring to increase soil fertility; and just human muscle power, instead of animal power, for agricultural tasks such as threshing, grinding, and irrigation. These differences suggest that Eurasian agriculture as of 1492 may have yielded on the average more calories and protein per person-hour of labor than Native American agriculture did.

SUCH DIFFERENCES IN food production constituted a major ultimate cause of the disparities between Eurasian and Native American societies. Among the resulting proximate factors behind the conquest, the most important included differences in germs, technology, political organization, and writing. Of these, the one linked most directly to the differences in food production was germs. The infectious diseases that regularly visited crowded Eurasian societies, and to which many Eurasians consequently developed immune or genetic resistance, included all of history’s most lethal killers: smallpox, measles, influenza, plague, tuberculosis, typhus, cholera, malaria, and others. Against that grim list, the sole crowd infectious diseases that can be attributed with certainty to pre-Columbian Native American societies were nonsyphilitic treponemas. (As I explained in Chapter 11, it remains uncertain whether syphilis arose in Eurasia or in the Americas, and the claim that human tuberculosis was present in the Americas before Columbus is in my opinion unproven.)

This continental difference in harmful germs resulted paradoxically from the difference in useful livestock. Most of the microbes responsible for the infectious diseases of crowded human societies evolved from very similar ancestral microbes causing infectious diseases of the domestic animals with which food producers began coming into daily close contact around 10,000 years ago. Eurasia harbored many domestic animal species and hence developed many such microbes, while the Americas had very few of each. Other reasons why Native American societies evolved so few lethal microbes were that villages, which provide ideal breeding grounds for epidemic diseases, arose thousands of years later in the Americas than in Eurasia; and that the three regions of the New World supporting urban societies (the Andes, Mesoamerica, and the U.S. Southeast) were never connected by fast, high-volume trade on the scale that brought plague, influenza, and possibly smallpox to Europe from Asia. As a result, even malaria and yellow fever, the infectious diseases that eventually became major obstacles to European colonization of the American tropics, and that posed the biggest barrier to the construction of the Panama Canal, are not American diseases at all but are caused by microbes of Old World tropical origin, introduced to the Americas by Europeans.

Rivaling germs as proximate factors behind Europe’s conquest of the Americas were the differences in all aspects of technology. These differences stemmed ultimately from Eurasia’s much longer history of densely populated, economically specialized, politically centralized, interacting and competing societies dependent on food production. Five areas of technology may be singled out:

First, metals—initially copper, then bronze, and finally iron—were used for tools in all complex Eurasian societies as of 1492. In contrast, although copper, silver, gold, and alloys were used for ornaments in the Andes and some other parts of the Americas, stone and wood and bone were still the principal materials for tools in all Native American societies, which made only limited local use of copper tools.

Second, military technology was far more potent in Eurasia than in the Americas. European weapons were steel swords, lances, and daggers, supplemented by small firearms and artillery, while body armor and helmets were also made of solid steel or else of chain mail. In place of steel, Native Americans used clubs and axes of stone or wood (occasionally copper in the Andes), slings, bows and arrows, and quilted armor, constituting much less effective protection and weaponry. In addition, Native American armies had no animals to oppose to horses, whose value for assaults and fast transport gave Europeans an overwhelming advantage until some Native American societies themselves adopted them.

Third, Eurasian societies enjoyed a huge advantage in their sources of power to operate machines. The earliest advance over human muscle power was the use of animals—cattle, horses, and donkeys—to pull plows and to turn wheels for grinding grain, raising water, and irrigating or draining fields. Waterwheels appeared in Roman times and then proliferated, along with tidal mills and windmills, in the Middle Ages. Coupled to systems of geared wheels, those engines harnessing water and wind power were used not only to grind grain and move water but also to serve myriad manufacturing purposes, including crushing sugar, driving blast furnace bellows, grinding ores, making paper, polishing stone, pressing oil, producing salt, producing textiles, and sawing wood. It is conventional to define the Industrial Revolution arbitrarily as beginning with the harnessing of steam power in 18th-century England, but in fact an industrial revolution based on water and wind power had begun already in medieval times in many parts of Europe. As of 1492, all of those operations to which animal, water, and wind power were being applied in Eurasia were still being carried out by human muscle power in the Americas.

Long before the wheel began to be used in power conversion in Eurasia, it had become the basis of most Eurasian land transport—not only for animal-drawn vehicles but also for human-powered wheelbarrows, which enabled one or more people, still using just human muscle power, to transport much greater weights than they could have otherwise. Wheels were also adopted in Eurasian pottery making and in clocks. None of those uses of the wheel was adopted in the Americas, where wheels are attested only in Mexican ceramic toys.

The remaining area of technology to be mentioned is sea transport. Many Eurasian societies developed large sailing ships, some of them capable of sailing against the wind and crossing the ocean, equipped with sextants, magnetic compasses, sternpost rudders, and cannons. In capacity, speed, maneuverability, and seaworthiness, those Eurasian ships were far superior to the rafts that carried out trade between the New World’s most advanced societies, those of the Andes and Mesoamerica. Those rafts sailed with the wind along the Pacific coast. Pizarro’s ship easily ran down and captured such a raft on his first voyage toward Peru.

IN ADDITION TO their germs and technology, Eurasian and Native American societies differed in their political organization. By late medieval or Renaissance times, most of Eurasia had come under the rule of organized states. Among these, the Habsburg, Ottoman, and Chinese states, the Mogul state of India, and the Mongol state at its peak in the 13th century started out as large polyglot amalgamations formed by the conquest of other states. For that reason they are generally referred to as empires. Many Eurasian states and empires had official religions that contributed to state cohesion, being invoked to legitimize the political leadership and to sanction wars against other peoples. Tribal and band societies in Eurasia were largely confined to the Arctic reindeer herders, the Siberian hunter-gatherers, and the hunter-gatherer enclaves in the Indian subcontinent and tropical Southeast Asia.

The Americas had two empires, those of the Aztecs and Incas, which resembled their Eurasian counterparts in size, population, polyglot makeup, official religions, and origins in the conquest of smaller states. In the Americas those were the sole two political units capable of mobilizing resources for public works or war on the scale of many Eurasian states, whereas seven European states (Spain, Portugal, England, France, Holland, Sweden, and Denmark) had the resources to acquire American colonies between 1492 and 1666. The Americas also held many chiefdoms (some of them virtually small states) in tropical South America, Mesoamerica beyond Aztec rule, and the U.S. Southeast. The rest of the Americas was organized only at the tribal or band level.

The last proximate factor to be discussed is writing. Most Eurasian states had literate bureaucracies, and in some a significant fraction of the populace other than bureaucrats was also literate. Writing empowered European societies by facilitating political administration and economic exchanges, motivating and guiding exploration and conquest, and making available a range of information and human experience extending into remote places and times. In contrast, use of writing in the Americas was confined to the elite in a small area of Mesoamerica. The Inca Empire employed an accounting system and mnemonic device based on knots (termed quipu), but it could not have approached writing as a vehicle for transmitting detailed information.

THUS, EURASIAN SOCIETIES in the time of Columbus enjoyed big advantages over Native American societies in food production, germs, technology (including weapons), political organization, and writing. These were the main factors tipping the outcome of the post-Columbian collisions. But those differences as of A.D. 1492 represent just one snapshot of historical trajectories that had extended over at least 13,000 years in the Americas, and over a much longer time in Eurasia. For the Americas, in particular, the 1492 snapshot captures the end of the independent trajectory of Native Americans. Let us now trace out the earlier stages of those trajectories.

Table 18.1 summarizes approximate dates of the appearance of key developments in the main “homelands” of each hemisphere (the Fertile Crescent and China in Eurasia, the Andes and Amazonia and Mesoamerica in the Americas). It also includes the trajectory for the minor New World homeland of the eastern United States, and that for England, which is not a homeland at all but is listed to illustrate how rapidly developments spread from the Fertile Crescent.

This table is sure to horrify any knowledgeable scholar, because it reduces exceedingly complex histories to a few seemingly precise dates. In reality, all of those dates are merely attempts to label arbitrary points along a continuum. For example, more significant than the date of the first metal tool found by some archaeologist is the time when a significant fraction of all tools was made of metal, but how common must metal tools be to rate as “widespread”? Dates for the appearance of the same development may differ among different parts of the same homeland. For instance, within the Andean region pottery appears about 1,300 years earlier in coastal Ecuador (3100 B.C.) than in Peru (1800 B.C.). Some dates, such as those for the rise of chiefdoms, are more difficult to infer from the archaeological record than are dates of artifacts like pottery or metal tools. Some of the dates in Table 18.1 are very uncertain, especially those for the onset of American food production. Nevertheless, as long as one understands that the table is a simplification, it is useful for comparing continental histories.

The table suggests that food production began to provide a large fraction of human diets around 5,000 years earlier in the Eurasian homelands than in those of the Americas. A caveat must be mentioned immediately: while there is no doubt about the antiquity of food production in Eurasia, there is controversy about its onset in the Americas. In particular, archaeologists often cite considerably older claimed dates for domesticated plants at Coxcatlán Cave in Mexico, at Guitarrero Cave in Peru, and at some other American sites than the dates given in the table. Those claims are now being reevaluated for several reasons: recent direct radiocarbon dating of crop remains themselves has in some cases been yielding younger dates; the older dates previously reported were based instead on charcoal thought to be contemporaneous with the plant remains, but possibly not so; and the status of some of the older plant remains as crops or just as collected wild plants is uncertain. Still, even if plant domestication did begin earlier in the Americas than the dates shown in Table 18.1, agriculture surely did not provide the basis for most human calorie intake and sedentary existence in American homelands until much later than in Eurasian homelands.

TABLE 18.1 Historical Trajectories of Eurasia and the Americas

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 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.

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 18.1 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 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 disputed 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 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 Mesoamerica’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 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 World was constricted over the whole length of Central America and especially at Panama. Not least, the Americas were more fragmented by areas unsuitable for food production or for dense human populations. These ecological barriers included the rain forests of the Panamanian isthmus separating Mesoamerican societies from Andean and Amazonian societies; the deserts of northern Mexico separating Mesoamerica from U.S. southwestern and southeastern societies; dry areas of Texas separating the U.S. Southwest from the Southeast; and the deserts and high mountains fencing off U.S. Pacific coast areas that would otherwise have been suitable for food production. As a result, there was no diffusion of domestic animals, writing, or political entities, and limited or slow diffusion of crops and technology, between the New World centers of Mesoamerica, the eastern United States, and the Andes and Amazonia.

Some specific consequences of these barriers within the Americas deserve mention. Food production never diffused from the U.S. Southwest and Mississippi Valley to the modern American breadbaskets of California and Oregon, where Native American societies remained hunter-gatherers merely because they lacked appropriate domesticates. The llama, guinea pig, and potato of the Andean highlands never reached the Mexican highlands, so Mesoamerica and North America remained without domestic mammals except for dogs. Conversely, the domestic sunflower of the eastern United States never reached Mesoamerica, and the domestic turkey of Mesoamerica never made it to South America or the eastern United States. Mesoamerican corn and beans took 3,000 and 4,000 years, respectively, to cover the 700 miles from Mexico’s farmlands to the eastern U.S. farmlands. After corn’s arrival in the eastern United States, seven centuries more passed before the development of a corn variety productive in North American climates triggered the Mississippian emergence. Corn, beans, and squash may have taken several thousand years to spread from Mesoamerica to the U.S. Southwest. While Fertile Crescent crops spread west and east sufficiently fast to preempt independent domestication of the same species or else domestication of closely related species elsewhere, the barriers within the Americas gave rise to many such parallel domestications of crops.

As striking as these effects of barriers on crop and livestock diffusion are the effects on other features of human societies. Alphabets of ultimately eastern Mediterranean origin spread throughout all complex societies of Eurasia, from England to Indonesia, except for areas of East Asia where derivatives of the Chinese writing system took hold. In contrast, the New World’s sole writing systems, those of Mesoamerica, never spread to the complex Andean and eastern U.S. societies that might have adopted them. The wheels invented in Mesoamerica as parts of toys never met the llamas domesticated in the Andes, to generate wheeled transport for the New World. From east to west in the Old World, the Macedonian Empire and the Roman Empire both spanned 3,000 miles, the Mongol Empire 6,000 miles. But the empires and states of Mesoamerica had no political relations with, and apparently never even heard of, the chiefdoms of the eastern United States 700 miles to the north or the empires and states of the Andes 1,200 miles to the south.

The greater geographic fragmentation of the Americas compared with Eurasia is also reflected in distributions of languages. Linguists agree in grouping all but a few Eurasian languages into about a dozen language families, each consisting of up to several hundred related languages. For example, the Indo-European language family, which includes English as well as French, Russian, Greek, and Hindi, comprises about 144 languages. Quite a few of those families occupy large contiguous areas—in the case of Indo-European, the area encompassing most of Europe east through much of western Asia to India. Linguistic, historical, and archaeological evidence combines to make clear that each of these large, contiguous distributions stems from a historical expansion of an ancestral language, followed by subsequent local linguistic differentiation to form a family of related languages (Table 18.2). Most such expansions appear to be attributable to the advantages that speakers of the ancestral language, belonging to food-producing societies, held over hunter-gatherers. We already discussed such historical expansions in Chapters 16 and 17 for the Sino-Tibetan, Austronesian, and other East Asian language families. Among major expansions of the last millennium are those that carried Indo-European languages from Europe to the Americas and Australia, the Russian language from eastern Europe across Siberia, and Turkish (a language of the Altaic family) from Central Asia westward to Turkey.

With the exception of the Eskimo-Aleut language family of the American Arctic and the Na-Dene language family of Alaska, northwestern Canada, and the U.S. Southwest, the Americas lack examples of large-scale language expansions widely accepted by linguists. Most linguists specializing in Native American languages do not discern large, clear-cut groupings other than Eskimo-Aleut and Na-Dene. At most, they consider the evidence sufficient only to group other Native American languages (variously estimated to number from 600 to 2,000) into a hundred or more language groups or isolated languages. A controversial minority view is that of the linguist Joseph Greenberg, who groups all Native American languages other than Eskimo-Aleut and Na-Dene languages into a single large family, termed Amerind, with about a dozen subfamilies.

TABLE 18.2 Language Expansions in the Old World

Some of Greenberg’s subfamilies, and some groupings recognized by more-traditional linguists, may turn out to be legacies of New World population expansions driven in part by food production. These legacies may include the Uto-Aztecan languages of Mesoamerica and the western United States, the Oto-Manguean languages of Mesoamerica, the Natchez-Muskogean languages of the U.S. Southeast, and the Arawak languages of the West Indies. But the difficulties that linguists have in agreeing on groupings of Native American languages reflect the difficulties that complex Native American societies themselves faced in expanding within the New World. Had any food-producing Native American peoples succeeded in spreading far with their crops and livestock and rapidly replacing hunter-gatherers over a large area, they would have left legacies of easily recognized language families, as in Eurasia, and the relationships of Native American languages would not be so controversial.

Thus, we have identified three sets of ultimate factors that tipped the advantage to European invaders of the Americas: Eurasia’s long head start on human settlement; its more effective food production, resulting from greater availability of domesticable wild plants and especially of animals; and its less formidable geographic and ecological barriers to intracontinental diffusion. A fourth, more speculative ultimate factor is suggested by some puzzling non-inventions in the Americas: the non-inventions of writing and wheels in complex Andean societies, despite a time depth of those societies approximately equal to that of complex Mesoamerican societies that did make those inventions; and wheels’ confinement to toys and their eventual disappearance in Mesoamerica, where they could presumably have been useful in human-powered wheelbarrows, as in China. These puzzles remind one of equally puzzling non-inventions, or else disappearances of inventions, in small isolated societies, including Aboriginal Tasmania, Aboriginal Australia, Japan, Polynesian islands, and the American Arctic. Of course, the Americas in aggregate are anything but small: their combined area is fully 76 percent that of Eurasia, and their human population as of A.D. 1492 was probably also a large fraction of Eurasia’s. But the Americas, as we have seen, are broken up into “islands” of societies with tenuous connections to each other. Perhaps the histories of Native American wheels and writing exemplify the principles illustrated in a more extreme form by true island societies.

AFTER AT LEAST 13,000 years of separate developments, advanced American and Eurasian societies finally collided within the last thousand years. Until then, the sole contacts between human societies of the Old and the New Worlds had involved the hunter-gatherers on opposite sides of the Bering Strait.

There were no Native American attempts to colonize Eurasia, except at the Bering Strait, where a small population of Inuit (Eskimos) derived from Alaska established itself across the strait on the opposite Siberian coast. The first documented Eurasian attempt to colonize the Americas was by the Norse at Arctic and sub-Arctic latitudes (Figure 18.1). Norse from Norway colonized Iceland in A.D. 874, then Norse from Iceland colonized Greenland in A.D. 986, and finally Norse from Greenland repeatedly visited the northeastern coast of North America between about A.D. 1000 and 1350. The sole Norse archaeological site discovered in the Americas is on Newfoundland, possibly the region described as Vinland in Norse sagas, but these also mention landings evidently farther north, on the coasts of Labrador and Baffin Island.

Iceland’s climate permitted herding and extremely limited agriculture, and its area was sufficient to support a Norse-derived population that has persisted to this day. But most of Greenland is covered by an ice cap, and even the two most favorable coastal fjords were marginal for Norse food production. The Greenland Norse population never exceeded a few thousand. It remained dependent on imports of food and iron from Norway, and of timber from the Labrador coast. Unlike Easter Island and other remote Polynesian islands, Greenland could not support a self-sufficient food-producing society, though it did support self-sufficient Inuit hunter-gatherer populations before, during, and after the Norse occupation period. The populations of Iceland and Norway themselves were too small and too poor for them to continue their support of the Greenland Norse population.

In the Little Ice Age that began in the 13th century, the cooling of the North Atlantic made food production in Greenland, and Norse voyaging to Greenland from Norway or Iceland, even more marginal than before. The Greenlanders’ last known contact with Europeans came in 1410 with an Icelandic ship that arrived after being blown off course. When Europeans finally began again to visit Greenland in 1577, its Norse colony no longer existed, having evidently disappeared without any record during the 15th century.

But the coast of North America lay effectively beyond the reach of ships sailing directly from Norway itself, given Norse ship technology of the period A.D. 986–1410. The Norse visits were instead launched from the Greenland colony, separated from North America only by the 200-mile width of Davis Strait. However, the prospect of that tiny marginal colony’s sustaining an exploration, conquest, and settlement of the Americas was nil. Even the sole Norse site located on Newfoundland apparently represents no more than a winter camp occupied by a few dozen people for a few years. The Norse sagas describe attacks on their Vinland camp by people termed Skraelings, evidently either Newfoundland Indians or Dorset Eskimos.

The fate of the Greenland colony, medieval Europe’s most remote outpost, remains one of archaeology’s romantic mysteries. Did the last Greenland Norse starve to death, attempt to sail off, intermarry with Eskimos, or succumb to disease or Eskimo arrows? While those questions of proximate cause remain unanswered, the ultimate reasons why Norse colonization of Greenland and America failed are abundantly clear. It failed because the source (Norway), the targets (Greenland and Newfoundland), and the time (A.D. 984–1410) guaranteed that Europe’s potential advantages of food production, technology, and political organization could not be applied effectively. At latitudes too high for much food production, the iron tools of a few Norse, weakly supported by one of Europe’s poorer states, were no match for the stone, bone, and wooden tools of Eskimo and Indian hunter-gatherers, the world’s greatest masters of Arctic survival skills.

THE SECOND EURASIAN attempt to colonize the Americas succeeded because it involved a source, target, latitude, and time that allowed Europe’s potential advantages to be exerted effectively. Spain, unlike Norway, was rich and populous enough to support exploration and subsidize colonies. Spanish landfalls in the Americas were at subtropical latitudes highly suitable for food production, based at first mostly on Native American crops but also on Eurasian domestic animals, especially cattle and horses. Spain’s transatlantic colonial enterprise began in 1492, at the end of a century of rapid development of European oceangoing ship technology, which by then incorporated advances in navigation, sails, and ship design developed by Old World societies (Islam, India, China, and Indonesia) in the Indian Ocean. As a result, ships built and manned in Spain itself were able to sail to the West Indies; there was nothing equivalent to the Greenland bottleneck that had throttled Norse colonization. Spain’s New World colonies were soon joined by those of half a dozen other European states.

The first European settlements in the Americas, beginning with the one founded by Columbus in 1492, were in the West Indies. The island Indians, whose estimated population at the time of their “discovery” exceeded a million, were rapidly exterminated on most islands by disease, dispossession, enslavement, warfare, and casual murder. Around 1508 the first colony was founded on the American mainland, at the Isthmus of Panama. Conquest of the two large mainland empires, those of the Aztecs and Incas, followed in 1519–1520 and 1532–1533, respectively. In both conquests European-transmitted epidemics (probably smallpox) made major contributions, by killing the emperors themselves, as well as a large fraction of the population. The overwhelming military superiority of even tiny numbers of mounted Spaniards, together with their political skills at exploiting divisions within the native population, did the rest. European conquest of the remaining native states of Central America and northern South America followed during the 16th and 17th centuries.

As for the most advanced native societies of North America, those of the U.S. Southeast and the Mississippi River system, their destruction was accomplished largely by germs alone, introduced by early European explorers and advancing ahead of them. As Europeans spread throughout the Americas, many other native societies, such as the Mandans of the Great Plains and the Sadlermiut Eskimos of the Arctic, were also wiped out by disease, without need for military action. Populous native societies not thereby eliminated were destroyed in the same way the Aztecs and Incas had been—by full-scale wars, increasingly waged by professional European soldiers and their native allies. Those soldiers were backed by the political organizations initially of the European mother countries, then of the European colonial governments in the New World, and finally of the independent neo-European states that succeeded the colonial governments.

Smaller native societies were destroyed more casually, by small-scale raids and murders carried out by private citizens. For instance, California’s native hunter-gatherers initially numbered about 200,000 in aggregate, but they were splintered among a hundred tribelets, none of which required a war to be defeated. Most of those tribelets were killed off or dispossessed during or soon after the California gold rush of 1848–52, when large numbers of immigrants flooded the state. As one example, the Yahi tribelet of northern California, numbering about 2,000 and lacking firearms, was destroyed in four raids by armed white settlers: a dawn raid on a Yahi village carried out by 17 settlers on August 6, 1865; a massacre of Yahis surprised in a ravine in 1866; a massacre of 33 Yahis tracked to a cave around 1867; and a final massacre of about 30 Yahis trapped in another cave by 4 cowboys around 1868. Many Amazonian Indian groups were similarly eliminated by private settlers during the rubber boom of the late 19th and early 20th centuries. The final stages of the conquest are being played out in the present decade, as the Yanomamo and other Amazonian Indian societies that remain independent are succumbing to disease, being murdered by miners, or being brought under control by missionaries or government agencies.

The end result has been the elimination of populous Native American societies from most temperate areas suitable for European food production and physiology. In North America those that survived as sizable intact communities now live mostly on reservations or other lands considered undesirable for European food production and mining, such as the Arctic and arid areas of the U.S. West. Native Americans in many tropical areas have been replaced by immigrants from the Old World tropics (especially black Africans, along with Asian Indians and Javanese in Suriname).

In parts of Central America and the Andes, the Native Americans were originally so numerous that, even after epidemics and wars, much of the population today remains Native American or mixed. That is especially true at high altitudes in the Andes, where genetically European women have physiological difficulties even in reproducing, and where native Andean crops still offer the most suitable basis for food production. However, even where Native Americans do survive, there has been extensive replacement of their culture and languages with those of the Old World. Of the hundreds of Native American languages originally spoken in North America, all except 187 are no longer spoken at all, and 149 of these last 187 are moribund in the sense that they are being spoken only by old people and no longer learned by children. Of the approximately 40 New World nations, all now have an Indo-European language or creole as the official language. Even in the countries with the largest surviving Native American populations, such as Peru, Bolivia, Mexico, and Guatemala, a glance at photographs of political and business leaders shows that they are disproportionately Europeans, while several Caribbean nations have black African leaders and Guyana has had Asian Indian leaders.

The original Native American population has been reduced by a debated large percentage: estimates for North America range up to 95 percent. But the total human population of the Americas is now approximately ten times what it was in 1492, because of arrivals of Old World peoples (Europeans, Africans, and Asians). The Americas’ population now consists of a mixture of peoples originating from all continents except Australia. That demographic shift of the last 500 years—the most massive shift on any continent except Australia—has its ultimate roots in developments between about 11,000 B.C. and A.D. 1.