Introduction

The history of North America is inextricably linked to the profound and catastrophic impact of disease. The arrival of European colonists introduced a host of pathogens to which Indigenous populations had no prior exposure or immunity, leading to a demographic collapse of unprecedented scale. This biological event, often termed the “Great Dying,” was not merely a tragic historical footnote but a central, transformative force that shaped the continent’s climate, enabled European conquest and settlement, and continues to influence modern-day public discourse and historical memory. An analysis of this period requires a multi-faceted approach, integrating demographic data, climatological theories, and a critical re-examination of colonial motivations and their enduring legacies.

I. The Demographic Catastrophe: The Great Dying of the Americas

The magnitude of the population decline following European contact is difficult to overstate. To understand its scale, it is first necessary to establish the size and complexity of the societies that existed before the arrival of Christopher Columbus. The world of pre-Columbian America was far from an unpopulated wilderness.

1.1 The Pre-Columbian World: Population and Diversity

Before 1492, the Americas were home to a vast and diverse population of Indigenous peoples, with a total continental estimate ranging from as low as 8 million to as many as 100 million people, with more recent scholarly consensus gravitating toward a figure of around 50 to 60 million. In North America specifically, estimates vary from 2.5 million to 18 million individuals. These were not scattered, nomadic groups but complex and varied societies engaged in agriculture, living in organized communities, and managing their land. The wide variance in historical population estimates is not an indication of a lack of data but rather a reflection of the challenges of demographic reconstruction and the historical biases that once dominated scholarship. Early historians, often influenced by Eurocentric viewpoints, frequently presented lower population figures. However, modern demographic research, employing more sophisticated methods and data sources, has consistently revised these numbers upward. This re-evaluation of the pre-contact population is a significant development in historical understanding, as it challenges the long-held colonial narrative of a “pristine wilderness” or an “empty land,” revealing it to be a later construct designed to justify colonization rather than a reflection of historical reality.  

The sheer number of people lost during this period represents the most severe demographic collapse in human history. Over the two centuries following 1492, the Indigenous population was reduced from a pre-contact estimate of 50-60 million to as few as 6 million people. This devastating loss was far more than a statistical decline; it was a profound decimation of entire cultures, intricate knowledge systems, and established social and political structures. The scale of this destruction is so immense that it is fittingly referred to as the “Great Dying” , a term that mirrors the Paleozoic era’s Permian-Triassic extinction event, which saw the loss of up to 96% of all marine species and 70% of terrestrial species. While the causes were entirely different, the term underscores the comparable scale of planetary-level impact.  

1.2 The Mechanisms of Catastrophe: Virgin-Soil Epidemics

The primary cause of this immense population decline was not military defeat but a biological phenomenon known as “virgin-soil epidemics”.

“Virgin soil epidemics” is the term historians and epidemiologists use — outbreaks in populations that have never before encountered a disease, meaning zero inherited immunity.

Diseases brought by Europeans (and Africans, via the slave trade) included:

• Smallpox (the deadliest and most transformative)
• Measles
• Influenza
• Typhus
• Whooping cough
• Bubonic plague (sporadically)

These diseases spread ahead of direct contact, carried by traders, enslaved people, and even items of exchange, creating epidemics in regions where Europeans hadn’t yet set foot.European colonists and their ships carried a host of infectious diseases—including smallpox, measles, influenza, bubonic plague, cholera, and typhus—to which Indigenous populations had no prior exposure and therefore no natural immunity. These diseases swept through communities with devastating speed, leading to mortality rates as high as 75-95% in some regions. The unique tragedy of these epidemics was that entire families would be stricken simultaneously, leaving no one healthy enough to care for the ill, fetch water, or prepare food, which created a fatal cycle of disease compounded by starvation. The collapse of these populations was not a simple cause-and-effect relationship of foreign disease. The impact of the epidemics went far beyond the sheer number of deaths, as the simultaneous incapacitation of all community members led to the complete breakdown of traditional care systems, food production, and social cohesion. This widespread social disruption left communities profoundly weakened and vulnerable to further European conquest and land seizure. Thus, a biological event created the conditions for political and social subjugation on a continental scale.  

The following table presents a summary of the population figures, illustrating the catastrophic decline of Indigenous populations.

II. The Unforeseen Climate Legacy: An Anthropogenic Event

Emerging academic consensus is beginning to reframe the Great Dying not just as a historical event but as an anthropogenic force with global consequences, providing an important counterpoint to the more commonly understood climate impacts of the Industrial Revolution. The parallel to the Permian-Triassic extinction event is a powerful thematic link that underscores the scale of both events. The first “Great Dying” was a natural geological catastrophe that resulted in a mass extinction and a significant temperature increase due to volcanic activity. The second “Great Dying,” a human-induced demographic collapse, resulted in a measurable global climate shift in the opposite direction, leading to a period of global cooling. This parallel demonstrates that human actions, even unintentional ones, had a planet-altering effect long before the advent of industrialization.  

2.1 The Mechanism: From Depopulation to Global Cooling

The link between the Indigenous demographic collapse and global climate change is a recent but compelling finding. As the Indigenous population plummeted, vast swaths of land that had been cleared and cultivated for centuries were abandoned. This abandoned land, an area roughly the size of France, was subsequently reforested. This new growth, including wild vegetation and “weeds,” sequestered massive amounts of carbon dioxide (CO2​) from the atmosphere. Scientists have found that this large-scale reforestation resulted in a drop of 7-10 parts per million (ppm) in atmospheric CO2​ levels. This drop in atmospheric carbon coincided with, and is believed to have intensified, a period of widespread cooling known as the “Little Ice Age,” which spanned from approximately 1300 to 1850 CE. While other natural factors, such as volcanic activity and low sunspot activity, may have contributed to the cooling, researchers suggest that the “genocide-generated drop in CO2​” was a critical factor in achieving the full extent of the cooling seen during the 16th century. This reveals a somber and complex reality: an immense historical tragedy had a direct, measurable effect on the planet’s climate. The implications are profound, as this evidence suggests that human activity had a global climate impact centuries earlier than previously thought, predating the Industrial Revolution by a significant margin.  

III. The Role of Disease in Conquest and Colonization

Disease was a crucial factor in the European colonization of the Americas, but its role differed significantly between the Spanish and English projects, revealing two distinct colonial models.

3.1 The Spanish Model: Disease as an Auxiliary of Conquest

The Spanish colonial project, particularly in Mesoamerica, was defined by a focus on gold, wealth extraction, and the subjugation of large, pre-existing Indigenous empires. The conquest of the Aztec Empire by Hernán Cortés is a prime example of disease serving as a de facto partner in conquest. Despite being vastly outnumbered, Cortés and his men were able to overcome the powerful Aztec civilization due to a combination of factors, including strategic alliances with oppressed Indigenous groups and, most critically, the devastating impact of smallpox. A single wave of the disease in 1520 killed an estimated 5-8 million people, weakening the Aztec military and social structure. When Cortés returned a year later, the empire was already weakened by both famine and disease, which made the final conquest significantly easier.  

The Spanish colonial model was not simply about military superiority; it was a complex interplay of military action and biological devastation. Disease weakened the Aztecs, making them vulnerable to conquest, and the conquest, in turn, further destabilized the society, making it more susceptible to subsequent epidemics. This created a symbiotic, causal loop in which disease served as a force multiplier, making the military efforts of the Spanish conquistadors feasible against a powerful empire.  

3.2 The English Model: Disease as a Precursor to Settlement

In stark contrast, the English colonial project in North America was driven by different motivations and took a different form. The English failed to find the gold and silver that the Spanish had sought. Instead, their goals were centered on establishing permanent, family-based settlements and building a new society free from spiritual persecution. Their economic model was based on the family farm and, in the southern colonies, on labor-intensive commercial agriculture, particularly tobacco. The constant tension between English settlers and Indigenous peoples often resulted in conflict, and the English frequently waged war against Native Americans.  

In this settler-colonial model, disease served a different, though equally critical, function. While the Spanish used disease to defeat empires they sought to control, the English used it as a “clearing agent” to make the land available for their ever-growing population of settlers. The devastating epidemics that swept through New England before the arrival of the Pilgrims, for example, cleared the way for English settlements. This dynamic gave rise to an ideological justification, as seen in the words of Governor William Bradford, who referred to an outbreak as the “good hand of God” that was “sweeping away multitudes of the natives”. This perception of depopulation as a divine act fueled a settler-driven land hunger that was at the heart of their conflicts with Native Americans, a stark contrast to the French model of colonization, which was based more on a balanced fur trade with Indigenous allies and respected their territorial jurisdiction. The English colonial model relied on a continuous influx of colonists and the displacement of Indigenous populations, a process made significantly easier by the prior devastation wrought by disease.

III. The Role of Disease in Conquest and Colonization

Disease was a crucial factor in the European colonization of the Americas, but its role differed significantly between the Spanish and English projects, revealing two distinct colonial models.

3.1 The Spanish Model: Disease as an Auxiliary of Conquest

The Spanish colonial project, particularly in Mesoamerica, was defined by a focus on gold, wealth extraction, and the subjugation of large, pre-existing Indigenous empires. The conquest of the Aztec Empire by Hernán Cortés is a prime example of disease serving as a de facto partner in conquest. Despite being vastly outnumbered, Cortés and his men were able to overcome the powerful Aztec civilization due to a combination of factors, including strategic alliances with oppressed Indigenous groups and, most critically, the devastating impact of smallpox. A single wave of the disease in 1520 killed an estimated 5-8 million people, weakening the Aztec military and social structure. When Cortés returned a year later, the empire was already weakened by both famine and disease, which made the final conquest significantly easier.  

The Spanish colonial model was not simply about military superiority; it was a complex interplay of military action and biological devastation. Disease weakened the Aztecs, making them vulnerable to conquest, and the conquest, in turn, further destabilized the society, making it more susceptible to subsequent epidemics. This created a symbiotic, causal loop in which disease served as a force multiplier, making the military efforts of the Spanish conquistadors feasible against a powerful empire.  

3.2 The English Model: Disease as a Precursor to Settlement

In stark contrast, the English colonial project in North America was driven by different motivations and took a different form. The English failed to find the gold and silver that the Spanish had sought. Instead, their goals were centered on establishing permanent, family-based settlements and building a new society free from spiritual persecution. Their economic model was based on the family farm and, in the southern colonies, on labor-intensive commercial agriculture, particularly tobacco. The constant tension between English settlers and Indigenous peoples often resulted in conflict, and the English frequently waged war against Native Americans.  

In this settler-colonial model, disease served a different, though equally critical, function. While the Spanish used disease to defeat empires they sought to control, the English used it as a “clearing agent” to make the land available for their ever-growing population of settlers. The devastating epidemics that swept through New England before the arrival of the Pilgrims, for example, cleared the way for English settlements. This dynamic gave rise to an ideological justification, as seen in the words of Governor William Bradford, who referred to an outbreak as the “good hand of God” that was “sweeping away multitudes of the natives”. This perception of depopulation as a divine act fueled a settler-driven land hunger that was at the heart of their conflicts with Native Americans, a stark contrast to the French model of colonization, which was based more on a balanced fur trade with Indigenous allies and respected their territorial jurisdiction. The English colonial model relied on a continuous influx of colonists and the displacement of Indigenous populations, a process made significantly easier by the prior devastation wrought by disease.

IV. Echoes of a Catastrophe: The Enduring Narrative

The historical reality of the Great Dying continues to echo in the political and social narratives of North America. The demographic vacuum created by the catastrophe set the stage for later policies of expansion and helped shape the racial and historical narratives that persist to this day.

4.1 From Depopulation to Policy: Justifying Expansion

The absence created by the Great Dying directly fueled later policies of expansion. The immense population collapse of the 16th and 17th centuries created the perception of “empty” or “unused” land, a vacuum that the doctrine of Manifest Destiny was created to fill. Manifest Destiny, the belief that the United States was divinely ordained to expand westward, rationalized the forced removal of American Indians under the premise that they were “not using the land to its full potential,” leaving it “uncultivated” and therefore “wasted”. This ideology, fueled by the perception of a depopulated landscape, was used to justify policies such as the Indian Removal Act of 1830, which led to the forced migration of tens of thousands of Indigenous people.  

The Proclamation Line of 1763 is a key example of the tensions created by this dynamic. The British Crown, having witnessed the devastating and costly conflicts of Pontiac’s War, sought to manage tensions by prohibiting colonial expansion west of the Appalachian Mountains. However, American colonists, driven by their hunger to expand into the seemingly “empty” lands, viewed this measure as a repressive infringement on their “charter rights” and a threat to their self-governance. In this sense, the biological catastrophe of the Great Dying set the stage for the ideological conflicts that would ultimately lead to the American Revolution.  

4.2 The Legacy of Erasure and Racialization

The historical narrative of Indigenous peoples in the United States, as taught in many public school curricula, is often incomplete and Eurocentric. It frequently depicts American Indians as victims and largely ends their story after the forced relocations of the 1830s, creating a narrative of a people who “disappeared” or were no longer a relevant political or social force. This historical erasure is a direct second-order consequence of the Great Dying, as it perpetuates the colonial myth of a conquered, and now absent, people. The curriculum also fails to make distinctions between individual tribes, treating them as a single, collective entity and perpetuating stereotypes of “warlike, half-naked savages”.  

This historical erasure is intrinsically tied to the social construction of “whiteness” in North America. The Spanish, Mexican, and American colonial regimes all used a form of white supremacy to maintain dominance and justify their eliminatory policies. In the American context, the definition of “whiteness” was fluid and was used to create a unifying identity for European Americans by framing Native Americans as a collective, racialized “other”. The act of racializing Indigenous peoples as a singular “other,” rather than acknowledging their diverse nations, was a deliberate tool used by European-American settlers to unite their own disparate groups and justify their policies of displacement and violence. This demonstrates how the demographic collapse facilitated the creation of a modern, racialized social hierarchy that persists to this day.  

V. Conclusion: Towards a More Complete History

The role of disease in the history of North America was not a secondary factor but a central, transformative force. The “Great Dying” stands as one of the most significant demographic events in human history, shaping not only the course of colonization but also the very climate of the planet. The immense loss of life enabled the specific forms of colonial conquest undertaken by the Spanish and English, creating a vacuum that was later filled by a new ideology of expansion and manifest destiny. This tragic history continues to influence public memory, educational narratives, and the racial hierarchies of modern society.

A more complete understanding of this period requires moving beyond a simple narrative of conquest and recognizing the profound and complex role that biological forces played in the subjugation and displacement of a continent’s population. It necessitates acknowledging the full scale of the catastrophe, understanding its environmental consequences, and confronting the historical erasure that continues to obscure the rich history of Indigenous peoples. It is only by facing this history in its entirety that we can begin to address its modern legacies and work toward a more just and accurate historical narrative.

Demography & Population Studies

• The Great Dying (c. 1520 – 1700 CE) – Climate in Arts and History
• Population history of the Indigenous peoples of the Americas
• Native American Population Estimates When Columbus Arrived In 1492
• American Indian demographics | Research Starters
• Historical demography of Native Americans | Research Starters

Disease & Epidemics

• Virgin Soil Epidemics – Intro to Native American Studies
• The ‘Great Dying’ | ScienceDaily
• AD 1520–62: ‘Virgin-soil’ epidemics devastate Native populations
• Native American disease and epidemics – Wikipedia
• The Columbian Exchange: A History of Disease, Food, and Ideas

Climate & Environmental Impact

• ‘Great Dying’ in Americas disturbed Earth’s climate | UCL News
• The Great Dying and the Little Ice Age
• 252 million year old climate crisis and the ‘Great Dying’ – Frontiers

Colonization & Conquest

• Spanish vs English Colonization | Essay Example
• Comparing Settlement Patterns: New Spain, New France, and British North America
• Spanish conquest of the Aztec Empire – Wikipedia
• How smallpox devastated the Aztecs – PBS
• Battle of Tenochtitlan | Britannica
• Treaty of Niagara: Pontiac’s War

Expansion & Manifest Destiny

• Manifest Destiny – Wikipedia
• Manifest Destiny and Indian Removal
• Proclamation Line of 1763 | Mount Vernon
• Proclamation of 1763 | Research Starters
• What role did territorial expansion play in the American Revolution? – Reddit
• Season of Independence | Museum of the American Revolution

Race, Identity & Historical Narratives

• Journal of American Indian Education
• The Land of Disenchantment: Settler Colonialism, White Supremacy
• The Roots of Spanish Racialized Thinking in Colonial America
• White people (racial classification) | Research Starters
• White American | Research Starters