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The Effect of Diseases on Indigenous Americans Following European Colonization in the Americas

Much has been said regarding the fate of Indigenous American tribes during the period of colonization of European persons in what is now the United States. However, scientists as well as historians have made additional conclusions on the impact of early European colonization in the Americas, which is sometimes referred to as The Great Dying.

The advent of of Europeans to the Americas, particularly during the 1400-1600s is a bottleneck event. "A population bottleneck or genetic bottleneck is a sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts; or human activities such as specicide, widespread violence or intentional culling, and human population planning." See,

A science article published on March 1, 2019, in the Quaternary Science Reviews titled, Earth system impacts of the European arrival and Great Dying in the Americas after 1492, found that over 50 million Indigenous Americans died between 1492 and 1600, which resulted in a human instigated cooling of the Earth by reducing carbon dioxide or CO2.

"We estimate that 55 million indigenous people died following the European conquest of the Americas beginning in 1492. This led to the abandonment and secondary succession of 56 million hectares of land . . . These changes show that the Great Dying of the Indigenous Peoples of the Americas is necessary for a parsimonious explanation of the anomalous decrease in atmospheric CO2 at that time and the resulting decline in global surface air temperatures. These changes show that human actions had global impacts on the Earth system in the centuries prior to the Industrial Revolution. Our results also show that this aspect of the Columbian Exchange – the globalisation of diseases – had global impacts on the Earth system . . . We conclude that the Great Dying of the Indigenous Peoples of the Americas led to the abandonment of enough cleared land in the Americas that the resulting terrestrial carbon uptake had a detectable impact on both atmospheric CO2 and global surface air temperatures in the two centuries prior to the Industrial Revolution."

Therefore, many Indigenous American tribes had already been substantially reduced in number before the United States government was even formed. According to the same article, much of the death was attributable to the spread of diseases, rather than violence. "Part of a wider Columbian Exchange of once-separate continental fauna and flora, these epidemics were introduced by European settlers and African slaves and were passed on to an indigenous population that had not been previously exposed to these pathogens and therefore did not initially possess suitable antibodies (Dobyns, 1993; Noymer, 2011; Walker et al., 2015). Such diseases included smallpox, measles, influenza, the bubonic plague, and later malaria, diphtheria, typhus and cholera."

Many of the diseases were also carried by livestock, in addition to Europeans. In contrast, Indigenous American tribes within America did not have as many domesticated animals therefore there was an unequal reverse-transfer of diseases from the Americas and back to Europe.

"The relative absence of American diseases arriving in Europe can therefore be explained by the low number of domesticated animals in the pre-contact Americas (Diamond, 1997; Lewis and Maslin, 2018; McNeill, 1977). Thus, influenza, smallpox, bubonic plague and other diseases ravaged the Americas, and not vice versa."

Although future generations of some Indigenous American tribes eventually developed an immunity, potentially low-levels of genetic diversity between the tribes allowed these deadly pathogens to continue ravaging Indigenous American populations for decades. This may be because of the Founder Effect. "In population genetics, the founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population."

This science article was discussed by Business Insider on February 9, 2019. See, European colonizers killed so many indigenous Americans that the planet cooled down, a group of researchers concluded, Aylin Woodward, Business Insider, Feb 9, 2019,

The Quaternary Science Reviews article can be found here:

You can also download the article here:

Earth system impacts of the European arrival and Great Dying in the Americas after 1492
Download • 2.41MB


I cited to this article in my Original Complaint in Van Cleve v. Ross, et al., (See Paragraph 7) viewable here:

Van Cleve v. Ross, Original Complaint - Filed Version
Download PDF • 635KB


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