Infectious Diseases in the New World
Different European colonial settlements in the New World exposed indigenous populations to Christianity, forced labor, expulsion from their lands, and foreign diseases. Rampant epidemic disease, to which the natives had no prior exposure or resistance, was one of the main causes of the massive population decline of the indigenous populations of the Americas. As Europeans and African slaves began to arrive in the New World, they brought with them the infectious diseases of Europe and Africa. Soon after, observers noted that immense numbers of indigenous Americans began to die from these diseases. The scope of the epidemics over the years was tremendous, killing millions of people—possibly in excess of 90% of the population in the hardest hit areas.
This death toll was initially overlooked or downplayed because once introduced, the diseases raced ahead of European invasion in many areas. Disease killed off a sizable portion of the populations before European observations and written records were made. After the epidemics had already killed massive numbers of indigenous Americans, many newer European immigrants assumed that there had always been relatively few indigenous peoples.
One of the most devastating diseases was smallpox; other deadly diseases included typhus, measles, influenza, bubonic plague, cholera, malaria, mumps, yellow fever, and pertussis (whooping cough). The indigenous Americas also had a number of endemic diseases, such as tuberculosis (although once believed to have been brought from Europe, skeletal remains found in South America have since provided evidence of tuberculosis before the Spanish arrival) and an unusually virulent type of syphilis, which became rampant when brought back to the Old World. The transfer of disease between the Old World and New World was part of the phenomenon known as the Columbian Exchange.
The diseases brought to the New World proved to be exceptionally deadly to the indigenous populations, and the epidemics had very different effects in different regions of the Americas. The most vulnerable groups were those with a relatively small population and little built-up immunity. Many island-based groups were annihilated: the Caribs and Arawaks of the Caribbean nearly ceased to exist, as did the Beothuks of Newfoundland. While disease swept swiftly through the densely populated empires of Mesoamerica, the more scattered populations of North America saw a slower spread.
Population Decline
Estimates of the pre-Columbian population have ranged from 8.4 million to 112.5 million persons, while estimates of indigenous deaths generally range from 2 to 15 million. Before the arrival of Columbus in Hispaniola, the indigenous Taíno pre-contact population of several hundred thousand declined to 60,000 by 1509. The population of the indigenous peoples in Mexico declined by an estimated 90% (reduced to 1-2.5 million people) by the early 17th century. In Peru, the indigenous pre-contact population of approximately 6.5 million declined to 1 million by the early 17th century.
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Storming of the Teocalli by Cortez and His Troops
While epidemic disease was by far the leading cause of the population decline of the American indigenous peoples after 1492, there were other contributing factors--all of them related to European contact and colonization. One of these factors was warfare.