The Columbian Exchange: biological and demographic consequences of contact
Anchor (Master): Crosby, A. W. — The Columbian Exchange (1972)
Overview Beginner
When Columbus reached the Americas in 1492, he started something far bigger than conquest. Plants, animals, microbes, and people crossed the Atlantic in both directions, transforming both hemispheres. The historian Alfred Crosby named this two-way transfer the Columbian Exchange, and the name has stuck because it captures what actually happened better than any story of battles or heroes.
The biggest killer was not swords or guns. It was disease. Indigenous Americans had no immunity to smallpox, measles, and influenza, which had evolved in Eurasia's dense populations and livestock. Within a century, roughly 90% of the Indigenous population of the Americas died — tens of millions of people, the greatest demographic catastrophe in recorded human history.
This unit follows the Exchange in three directions. Eastward: maize, potatoes, tomatoes, tobacco, and chili peppers reached Europe, Africa, and Asia, reshaping food supplies everywhere. Westward: wheat, sugar, cattle, horses, pigs, and deadly microbes reached the Americas. Southward across the Atlantic: millions of enslaved Africans were transported to replace the dying Indigenous labor force. Charles Mann's 1493 argues this exchange created the first era of biological globalization — the modern world.
The biological exchange: crops, animals, and microbes Beginner
The Americas sent the world crops that would transform food supplies. Potatoes, domesticated in the Andes, fueled European population growth and became the staple of Ireland, northern Europe, and parts of China. Maize spread across Africa and southern Europe. Tomatoes reshaped Italian cuisine, chili peppers transformed Indian, Thai, Sichuan, and Hungarian cooking, and tobacco became a global addiction. Cassava became a lifeline crop across tropical Africa.
Europe sent the Americas wheat, rice, sugar cane, coffee, citrus, olives, grapes, and bananas — plus livestock: cattle, horses, pigs, sheep, goats, and chickens. The horse revolutionized Plains Indian cultures within a few generations, turning agricultural peoples into the mounted buffalo-hunting nations of the Great Plains. But pigs acted as what one historian called "ecological bulldozers," destroying forests and rooting up Indigenous gardens wherever they went feral.
The microbial transfer was the deadliest part. Eurasian crowd diseases — smallpox, measles, influenza, typhus, diphtheria, mumps — swept through populations with no prior exposure and no inherited immunity. Jared Diamond calls these pathogens Europe's "lethal gift of livestock," because most had originally jumped from domesticated animals that the Americas lacked.
The demographic catastrophe Beginner
The numbers are debated but the scale is not. Before 1492, somewhere between 30 and 100 million people lived in the Americas — complex civilizations, cities, and trade networks described in unit 32.09.01. By 1650, the population had fallen to perhaps 5 to 10 million. That is roughly nine out of every ten people dead within a century and a half.
Disease did most of the killing, and it moved faster than the Europeans themselves. Smallpox reached the Inca Empire through trade routes before Pizarro's soldiers arrived, killing the emperor Huayna Capac and triggering a civil war between his sons. Epidemics arrived in wave after wave — first smallpox in 1518, then measles, influenza, typhus — each striking a population still reeling from the last. Communities lost their elders, their healers, their knowledge keepers.
The catastrophe was not silent or passive. Indigenous people fled, negotiated, fought back, and rebuilt. But the scale of mortality destroyed political institutions, emptied cities, and broke chains of memory. Lands Europeans later described as "wilderness" were often abandoned agricultural landscapes whose caretakers had died.
Visual Beginner
Figure: The Columbian Exchange. Eastward flows (Americas to Afroeurasia): maize, potatoes, tomatoes, tobacco, chili peppers, cacao, cassava. Westward flows (Afroeurasia to the Americas): wheat, sugar, cattle, horses, pigs, and the crowd diseases — smallpox, measles, influenza, typhus — that drove the demographic collapse. The downward curve traces the Indigenous American population from an estimated 50-60 million at contact to a nadir near 1650.
| Date | Event |
|---|---|
| 1492 CE | Columbus reaches the Caribbean |
| 1518 CE | First smallpox epidemic in the Caribbean |
| 1520-1521 CE | Smallpox devastates central Mexico during Cortes's siege |
| c. 1525 CE | Smallpox reaches the Inca Empire, killing Huayna Capac |
| 1545 CE | Potosi silver discovered |
| c. 1565-1815 CE | Manila galleon trade links Asia, Americas, Europe |
| c. 1650 CE | Indigenous American population reaches nadir (~90% loss) |
| 1845-1852 CE | Irish Great Famine (potato blight) |
Worked example Beginner
Consider a single crop — the potato — and trace what it did on three continents.
The potato was domesticated in the Andes, where farmers bred it across thousands of varieties suited to high altitudes. It reached Europe in the late 1500s. Northern European peasants initially distrusted it, but its yields per acre far exceeded wheat, and it grew on poor land. Over the 1700s, the potato became the food base of northern and eastern Europe. Historians Nathan Nunn and Nancy Qian have shown that the potato accounts for a measurable share of European population growth and urbanization after 1700.
In Ireland, reliance on a single crop turned dangerous. When the water mold Phytophthora infestans arrived in 1845, it destroyed the harvest for years. Roughly one million people died and another million emigrated. The Great Famine was a Columbian Exchange tragedy played out three centuries late: an American crop, a European population, and a New World pathogen meeting again.
In China, the potato and sweet potato colonized uplands that rice could not reach, supporting population growth in mountainous regions. A single American crop reshaped demography on three continents — abundance in Europe, catastrophe in Ireland, expansion in China.
Check your understanding Beginner
Formal definition Intermediate+
This section fixes the analytical vocabulary used throughout the rest of the unit.
The Columbian Exchange designates the transfer of plants, animals, pathogens, technologies, and people between the Americas and Afroeurasia initiated by Columbus's 1492 voyage and continuing through the early modern period. The term was coined by Alfred Crosby in The Columbian Exchange: Biological and Cultural Consequences of 1492 (1972). The Exchange was two-way: American crops (maize, potatoes, tomatoes, tobacco, cassava, chili peppers, cacao, peanuts, squash) moved to Afroeurasia; Afroeurasian crops and livestock (wheat, rice, sugar cane, coffee, cattle, horses, pigs, sheep, goats) moved to the Americas; and Eurasian crowd diseases moved to the Americas with catastrophic demographic consequences.
"Crowd diseases" are epidemic pathogens that require large, dense host populations to persist, because they either kill or immunize their hosts rapidly. Smallpox, measles, influenza, typhus, diphtheria, mumps, and bubonic plague are the principal examples. They evolved in Afroeurasia over millennia of dense agricultural settlement and livestock domestication. Their arrival in immunologically naive populations — populations with no inherited or acquired immunity — produces virgin-soil epidemics with mortality rates far exceeding those in the pathogen's original host region.
Ecological imperialism, a concept developed by Crosby in Ecological Imperialism: The Biological Expansion of Europe, 900-1900 (1986), is the thesis that European success in temperate "Neo-Europes" (North America, Australia, New Zealand, southern South America) depended less on military or cultural superiority than on the pre-adapted biological package Europeans carried with them — their weeds, livestock, and diseases. On this view, "the Europeans won because their weeds, animals, and germs had already won for them."
The "Homogenocene", a term popularized by Charles Mann in 1493 (2011), is a proposed geological epoch defined by biological homogenization — the mixing of previously isolated biotas — beginning in 1492. It frames the Columbian Exchange as the boundary event of a new era in which Earth's ecosystems became globally integrated under human agency.
Counterexamples to common slips
Slip 1: "The Exchange was mostly about crops." Framing the Exchange as a story of potatoes and tomatoes erases its central event: the largest demographic catastrophe in human history. Roughly 90% of the Indigenous American population died. The human cost must anchor any account of the Exchange, not appear as an afterthought to a story about food.
Slip 2: "Europeans conquered through superior technology." Disease, not guns or steel, did the decisive work. Cortes and Pizarro succeeded because epidemics preceded and accompanied them, not because a few hundred soldiers could defeat empires of millions on their own. The Aztec and Inca conquests required tens of thousands of Indigenous allies and the catastrophic effects of virgin-soil epidemics.
Slip 3: "The Exchange was a balanced two-way trade." The Exchange was two-directional but radically asymmetric. Afroeurasia received crops that boosted its populations; the Americas received pathogens that destroyed theirs. Calling this a "trade" imposes a market metaphor on a biological catastrophe.
Slip 4: "Indigenous peoples simply died out." Despite catastrophic mortality, Indigenous peoples survived, adapted, resisted, and rebuilt. Genetic, cultural, and linguistic continuity persists across the Americas. The extinction narrative reproduces the colonial fiction of inevitable disappearance and erases living communities.
Key concepts: the Columbian Exchange as analytical framework Intermediate+
This section develops the conceptual machinery historians and scientists use to analyze the Exchange.
Crosby's concept and the "homogenization of the globe"
Crosby's 1972 argument was nontrivial because it reframed conquest as biology. Where earlier historians had explained European dominance through military, technological, or cultural superiority, Crosby located the decisive cause in organisms: pathogens, weeds, and livestock. The Exchange was not principally a political event but a biological one. Its central consequence was the "homogenization of the globe" — the breaking down of biogeographic isolation that had separated the world's life forms since the end of the Pleistocene.
This reframing matters analytically. If the conquest of the Americas is primarily a story of smallpox rather than of Spanish valor, then the standard narrative of European achievement collapses. Crosby did not deny that conquest occurred; he relocated its mechanism. The same reframing opens the question of agency: who "conquered" — Pizarro, or the microbes that travelled with him?
The demographic catastrophe: numbers, mechanisms, debate
Pre-contact population estimates vary widely because no census existed and because the catastrophe itself destroyed the evidence. The debate runs from David Henige's skeptical Numbers from Nowhere (1998), which argued for low estimates and warned against demographic inflation, to Henry Dobyns's high estimates of 90 to 112 million. William Denevan's The Native Population of the Americas in 1492 (1976) helped settle the range around 50 to 60 million, a figure most scholars now accept as a reasonable middle estimate.
The mechanism of decline is better understood than the initial count. A cascade of epidemics struck the Americas across the sixteenth century: smallpox first (from 1518), then measles, influenza, typhus, diphtheria, and mumps in successive waves. Because each epidemic killed and immunized survivors, the next pathogen met a smaller, weakened population still vulnerable to a different disease. The population reached its nadir around 1650, having lost roughly 90% of its pre-contact size — a mortality event without parallel in human history.
Why was the mortality so one-directional? Diamond's answer in Guns, Germs, and Steel points to livestock. Afroeurasia's many domesticated animals generated a reservoir of zoonotic pathogens that jumped to humans over millennia; the Americas, with very few domesticates, generated almost none. Eurasian populations coevolved with these diseases and acquired partial resistance; Americans had no such history.
Agricultural exchange and its global consequences
The westward transfer (Old World to New) introduced wheat, rice, sugar cane, coffee, citrus, olives, grapes, and bananas, along with cattle, horses, pigs, sheep, goats, and chickens. This biological package transformed American landscapes. Sugar plantations in the Caribbean and Brazil drove the demand for enslaved African labor. Feral pigs and cattle destroyed Island and forest ecosystems. Horses, escaping or stolen, reached the Great Plains within decades and made possible the mounted cultures of the Comanche, Lakota, and Crow.
The eastward transfer (New to Old) reshaped Afroeurasian demography. Maize transformed African and Chinese agriculture because it grew where older staples struggled. The potato's contribution to European population growth and urbanization has been quantified by Nunn and Qian, who estimate it accounts for a significant share of eighteenth- and nineteenth-century growth. These were not marginal additions; they were structural transformations of food systems.
Ecological consequences: weeds, grasslands, and "ecological imperialism"
The Exchange was not only about domesticated species. European weeds colonized the Americas with striking success. Crosby's Ecological Imperialism (1986) argued that European weeds, grasses, and livestock were pre-adapted to the disturbed soils left by disease and conquest, giving them an advantage over native species. European grasses replaced native vegetation on the pampas and the Great Plains, creating the grassland landscapes later settlers mistook for pristine nature.
The thesis has a sharp edge. If Europeans succeeded partly because their biological package had already "won" for them, then conquest appears less as an achievement of European civilization and more as a contingency of biology. The critique, developed below at the Master tier, is that biology alone cannot explain dispossession — violence, law, and settler institutions did decisive work that the biological frame can obscure. The link to community ecology and invasion ecology (see 19.10.*) is direct: the Exchange is the largest invasion event in human history.
The slave trade and the Exchange
The demographic catastrophe created a labor vacuum at the same moment that European planters discovered the profitability of sugar. The two facts joined. As Indigenous populations collapsed, colonists imported enslaved Africans to work the plantations and mines of the Caribbean, Brazil, and mainland Spanish America. The transatlantic slave trade (see 32.16.*) was thus not separate from the Exchange but a direct consequence of it. Eltis and Richardson's Atlas of the Transatlantic Slave Trade documents roughly 12.5 million Africans embarked. The racial categories that justified this trade are addressed in unit 30.04.03 (race and ethnicity) and 31.04.03 (human variation).
Silver and the first global economy
The Exchange was biological, but it fused with a monetary integration. Silver from Potosi (discovered 1545, in modern Bolivia) became the first global currency. Chinese demand for silver — driven by the Ming state's silver-based tax system — pulled Latin American metal across the Pacific via the Manila galleon (1565-1815) and across the Atlantic via Europe. The result was a global silver standard linking the Americas, Europe, Africa, India, and China into a single commercial system for the first time. This monetary layer of the Exchange connects to world-systems theory (30.07.03) and to the origins of the industrial revolution (32.18.*).
Exercises Intermediate+
Competing perspectives Master
Was it biology, or was it dispossession? The ecological imperialism debate
Crosby's ecological imperialism thesis has generated a sharp critique. The thesis holds that Europeans succeeded in temperate "Neo-Europes" because their biological package — weeds, livestock, diseases — was pre-adapted to thrive there. Critics grant the biology but argue that the thesis risks naturalizing conquest. If germs and weeds "won" the Americas for Europe, then the violence, law, and organized dispossession that actually removed Indigenous peoples can appear as afterthoughts.
Patrick Wolfe's work on settler colonialism offers the principal corrective. Wolfe argued that settler colonialism is a structure, not an event, organized around the logic of elimination — the persistent replacement of Indigenous peoples with settler populations through a combination of disease, removal, assimilation policy, and legal erasure. On this view, biology opened the door but institutions walked through it. Lorenzo Veracini has developed the same line, distinguishing settler colonialism as an ongoing structure from the one-time catastrophe of contact. The biological frame, taken alone, can obscure the fact that dispossession continued for centuries after the epidemics burned out, and that it was carried out by law and policy as much as by microbes.
The resolution is not to discard Crosby but to embed him. Biology explains the scale of demographic collapse; settler colonial studies explains what Europeans did with that collapse. The Exchange created the conditions; colonial institutions determined the outcome.
The syphilis question: did the Exchange run one way?
The asymmetry of disease exchange is striking. Eurasian pathogens devastated the Americas, but no comparable New World pandemic swept Europe. The one candidate is syphilis. The first recorded European syphilis epidemic broke out in 1495 among French troops besieging Naples, and it was far more virulent than the modern disease, suggesting a recently introduced pathogen adapting to a new host population. The traditional "Columbian hypothesis" holds that Columbus's crew carried an American treponemal infection back to Europe in 1493.
The debate remains unresolved. Skeptics, including Rothschild and Rothschild, have argued that pre-Columbian skeletal lesions in Europe show treponemal disease was already present. Harper, Zuckerman, and colleagues (2011) used genetic evidence to argue that all modern treponematoses share a common ancestor, but that the venereal syphilis lineage is consistent with a post-Columbian emergence or introduction. The genetics remain contested. The larger point survives: even if syphilis originated in the Americas, it did not produce anything like the demographic catastrophe that Eurasian diseases produced in the other direction. The asymmetry stands regardless of the syphilis verdict.
Pomeranz vs Landes: the "biological old regime" and the Great Divergence
Kenneth Pomeranz's The Great Divergence (2000) argued that before 1800 the most advanced regions of China, India, and Europe were comparably developed, and that Europe's breakthrough to industrialization depended on two contingent advantages — coal and colonies — rather than on deep cultural or institutional superiority. The "biological old regime" is the term for the pre-industrial economy: organic, land-bound, limited by the energy of sunlight captured in plants and the muscle of humans and animals. Within that regime, the Columbian Exchange was the decisive shock: it gave Europe access to the Americas' land and resources, relieving the ecological constraints that bound China and India.
David Landes's The Wealth and Poverty of Nations (1998) takes the opposite position, arguing that European cultural and institutional features — scientific inquiry, property rights, a work ethic — explain the divergence. The Pomeranz-Landes debate is really a debate about contingency versus convergence (see 19.08.03 on contingency vs convergence in evolution). For Pomeranz, the Exchange was a contingent windfall; for Landes, it was incidental to deeper causes. The Exchange's role in the divergence is inseparable from this historiographic disagreement, and it links directly to the industrial revolution (32.18.*) and to global inequality (30.07.03).
Mann's "Homogenocene" and the Anthropocene debate Master
Charles Mann's 1493 argues that 1492 marks the beginning of a new geological epoch defined by biological homogenization. He proposes the term "Homogenocene" — the age of sameness — to capture the mixing of previously isolated biotas that the Exchange initiated. On this view, Columbus is a boundary event in Earth history, not merely a figure in human history.
The proposal intersects with the formal Anthropocene debate. The Anthropocene Working Group has considered several candidate "golden spikes" — stratigraphic markers that would define the epoch's lower boundary. Simon Lewis and Mark Maslin proposed the "Orbis spike" of 1610 as one such marker. Their argument rests on a striking consequence of the Columbian Exchange: the demographic collapse of Indigenous American populations led to the abandonment of vast agricultural landscapes, which reforested and drew down atmospheric carbon dioxide. The CO2 drop, visible in Antarctic ice cores, is a global stratigraphic signal directly caused by the Exchange.
William Ruddiman's "early anthropogenic" hypothesis offers a related framing, arguing that human alteration of atmospheric chemistry began thousands of years earlier with agriculture and land clearance. The Exchange, on this account, accelerated and globalized a process already underway. The debate over whether the Anthropocene begins with agriculture, with 1492, or with the industrial revolution (27.07., 27.08.) is unresolved, but the Columbian Exchange is a serious candidate boundary. Its claim is that biological globalization — the Homogenocene — is itself a planetary-scale event comparable in magnitude to earlier mass extinctions (19.08.02, 19.10.*).
The Columbian Exchange and food history Master
The Exchange is legible in the world's cuisines, and reading those cuisines reveals how deep the transformation ran. Italian food without tomatoes, Irish food without potatoes, Indian and Thai food without chili peppers, Belgian food without chocolate — each is a post-1492 invention. The chili pepper, domesticated in the Americas, reached South Asia in the sixteenth century and became the defining flavor of regional cuisines that are now imagined as ancient and timeless. The disconnect between perceived antiquity and actual post-Columbian origin is itself evidence of how thoroughly the Exchange remade everyday life.
The potato's trajectory shows the Exchange's capacity for both abundance and catastrophe. It fueled European population growth for two centuries, then became the instrument of Ireland's Great Famine (1845-1852) when Phytophthora infestans — a New World pathogen meeting a New World crop in an Old World field — destroyed the harvest. The famine was a Columbian Exchange event played out centuries after 1492, an ecological time bomb planted by the original transfer. Maize took a different path: in Africa it became a labor crop bound to the plantation and slave-trade economies, linking the Exchange's biological and human layers.
Sugar deserves separate emphasis. A Southeast Asian plant refined through Arab and Mediterranean agriculture, sugar became the engine of the Caribbean plantation system. Its cultivation demanded intense labor, which the demographic collapse channeled into the transatlantic slave trade. Sugar's environmental consequences — deforestation, soil exhaustion, and the conversion of diverse island ecologies into monoculture — were among the Exchange's most destructive ecological legacies. The medical-anthropology frame of the nutrition transition (31.06.02) extends the story to the present: the global diet the Exchange created is now a driver of chronic disease.
Connections Master
This unit extends unit 32.14.01, which surveyed the Age of Exploration from multiple perspectives; here the focus narrows to the biological and demographic layer that unit introduced. The pre-contact American civilizations whose populations collapsed are those described in unit 32.09.01. The transatlantic slave trade, a direct consequence of the Exchange's demographic catastrophe, is treated in full in unit 32.16.. The Atlantic world the Exchange created — its silver, its plantation economies, its racial categories — produced the conditions for the revolutions of the late eighteenth century covered in unit 32.17. (the proposed hook to 32.17.02), and for the industrial revolution in unit 32.18.*.
The Exchange connects outward to the sciences. Disease dynamics link to infectious disease (35.02.) and population genetics (19.02.); the question of why Eurasia possessed more crowd diseases links to the evolution of virulence and host-pathogen coevolution. The agricultural transfers link to community ecology and invasion ecology (19.10.), since the Exchange is the largest biological invasion event on record. The "Homogenocene" framing links to earth history and the Anthropocene (27.07., 27.08.) and to macroevolutionary questions of mass extinction and contingency (19.08.). The racial categories forged to justify the slave trade link to race and ethnicity (30.04.03), human variation (31.04.03), and the postcolonial perspectives of development anthropology (31.06.03). The first global silver economy links to global inequality and world-systems theory (30.07.03) and to urbanization and trade routes (30.08.). The Austronesian and Indian Ocean networks that predated 1492 (32.01.02, 32.10., 31.05.03) provide the comparative baseline: earlier biological exchanges did not produce comparable demographic catastrophes because the connected populations already shared disease pools.
Historical and philosophical context Master
The Columbian Exchange as a concept is itself a historical artifact. For most of the modern era, the standard Western account of 1492 and its aftermath was a political and military story: discovery, conquest, colonization, the spread of civilization. Biology was a background fact, not a causal engine. What changed the frame was Crosby's 1972 monograph, which relocated the decisive mechanism of conquest in organisms rather than in soldiers or ideas. The concept's power is that it made the biological visible as history.
The reframing had political stakes. If smallpox, not Spanish valor, conquered the Americas, then the narrative of European achievement loses its foundation, as J.M. Blaut argued in The Colonizer's Model of the World (1993). At the same time, a purely biological account can become its own kind of alibi: if germs did the work, then human responsibility appears to dissolve. The historiography has therefore moved in two directions at once — granting the biological causality Crosby established while insisting, with Wolfe and Veracini, that the institutions of dispossession were deliberate and continuing. The Exchange is biological, but the colonial order built on top of it was constructed by people who made choices.
The deeper philosophical question the Exchange raises is about contingency in history. Diamond and Crosby argue for contingency: the asymmetry of disease and ecology was a product of biogeography — which continents had which animals and pathogens — not of any inherent superiority. Pomeranz extends the argument to the industrial divergence. Against them stand historians like Landes who favor deeper structural or cultural causes. The Exchange thus sits at the center of one of the most consequential debates in historical methodology: how much of the modern world's shape is the product of contingent events like 1492, and how much of deeper processes that would have produced similar outcomes regardless. The answer one gives shapes how one understands colonialism, inequality, and the legitimacy of the present global order.
Bibliography Master
Crosby, A. W. (1972). The Columbian Exchange: Biological and Cultural Consequences of 1492. Greenwood Press, Westport, CT.
Crosby, A. W. (1986). Ecological Imperialism: The Biological Expansion of Europe, 900-1900. Cambridge University Press, Cambridge.
Diamond, J. (1997). Guns, Germs, and Steel: The Fates of Human Societies. W. W. Norton, New York.
McNeill, W. H. (1963). The Rise of the West: A History of the Human Community. University of Chicago Press, Chicago.
Mann, C. C. (2005). 1491: New Revelations of the Americas Before Columbus. Knopf, New York.
Mann, C. C. (2011). 1493: Uncovering the New World Columbus Created. Knopf, New York.
Denevan, W. M., ed. (1976). The Native Population of the Americas in 1492. University of Wisconsin Press, Madison.
Henige, D. (1998). Numbers from Nowhere: The American Indian Contact Population Debate. University of Oklahoma Press, Norman.
Dobyns, H. F. (1966). "Estimating Aboriginal American Population: An Appraisal of Techniques with a New Hemispheric Estimate." Current Anthropology, 7(4), 395-416.
Nunn, N. and Qian, N. (2010). "The Columbian Exchange: A History of Disease, Food, and Ideas." Journal of Economic Perspectives, 24(2), 163-188.
Eltis, D. and Richardson, D. (2010). Atlas of the Transatlantic Slave Trade. Yale University Press, New Haven.
Pomeranz, K. (2000). The Great Divergence: China, Europe, and the Making of the Modern World Economy. Princeton University Press, Princeton.
Landes, D. S. (1998). The Wealth and Poverty of Nations: Why Some Are So Rich and Some So Poor. W. W. Norton, New York.
Blaut, J. M. (1993). The Colonizer's Model of the World: Geographical Diffusionism and Eurocentric History. Guilford Press, New York.
Wolfe, P. (2006). "Settler Colonialism and the Elimination of the Native." Journal of Genocide Research, 8(4), 387-409.
Veracini, L. (2010). Settler Colonialism: A Theoretical Overview. Palgrave Macmillan, Basingstoke.
Harper, K. N., Zuckerman, M. K., Harper, M. L., Hudson, R. R., and Armelagos, G. J. (2011). "The Origin and Antiquity of Syphilis Revisited: An Appraisal of Old World Pre-Columbian Evidence for Treponemal Infection." Yearbook of Physical Anthropology, 146, 99-133.
Lewis, S. L. and Maslin, M. A. (2015). "Defining the Anthropocene." Nature, 519, 171-180.
Ruddiman, W. F. (2005). "How Did Humans First Alter Global Climate?" Scientific American, 292(3), 46-53.
Restall, M. (2003). Seven Myths of the Spanish Conquest. Oxford University Press, Oxford.