What role did disease play in the conquest of the Americas by the Europeans?

The biological mingling of the Old World and the New World, which began in 1492, proved disastrous for the natives of the Americas. The consequences have been described as a ‘holocaust’ with no human author. The European invasion of the New World led to radical changes. The population was devastated by epidemics of diseases brought by the Spanish.  Those who survived, less than 15 per cent of the pre-Columbian population, became a servile class that worked in the plantations and mines of the Iberians. The Amerindian population in 1492 has been estimated at between 40 and 100 million, there is no consensus of opinion among experts and it remains controversial area. It had fallen to 250,000 by 1750. A similarly dramatic fall was experienced in Central Mexico where the population plummeted from 25 million in 1492 to 1 million in 1568. The New World population had been reduced by 90% by 1900. While epidemic disease was not the sole factor in the decline, it was indisputably the most prominent. Karlen said that ‘contact between previously separated populations’[1] was the chief culprit in the Amerindians fate. The Leyenda Negra, the ‘Black Legend’, which places all the blame on Spanish cruelty, should be revised because of the new evidence surrounding the role of disease.

The Conquistadors established the Spanish Empire in America in the period from the first voyage of Christopher Columbus, to 1550. The European explorers subjugated the Native American peoples and their civilizations. The successful conquest of Mexican Aztec and Peruvian Inca empires by a handful of Spanish conquistadors led by Hernando Cortés (Aztec) and Francisco Pizarro (Inca), resulted in large part from the epidemics that decimated the native defenders ‘before a sword could be unsheathed’[2]. The goals of the Europeans in the conquest were to convert the Indians to Christianity while at the same time increasing trading possibilities and ‘accessing’ the great mineral wealth of the Americas By the 1530s a stable Spanish society had been established in Mexico out of the ruins of the Aztec Empire and a similar process was well under way in Inca Peru by the early 1550s[3].  By 1700 the Spanish Empire in the Americas nominally covered a huge area from modern New Mexico to the river Plate[4] and the indigenous population had virtually been wiped out.

The Americas were remarkably free of serious disease before meeting the Europeans and the Africans who accompanied them. The situation changed dramatically after the explorers arrived and turned the ecological equilibrium upside down. Smallpox and measles were predominately childhood diseases in Africa and Europe, where they were endemic. However, the natives had no immunity to these ‘crowd’ diseases. They experienced them as ‘virgin soil’. In the main they had no domesticated animals and so had not learnt to live with the diseases from dogs, pigs and cattle. This led to epidemics such as the swine fever of Hispanolia, 1493-1494. The Old World pathogens resulted in untold deaths in the sixteenth century. The natives’ diseases had had little time to develop compared to the Europeans. So when the European ‘crowd’ diseases hit they were devastated. The small or isolated populations were unable to ‘hit-back’ against the Europeans with their own diseases. McNeil said ‘climatic conditions prevented new tropical diseases from penetrating Europe’[5]. Pandemics ultimately wiped out entire peoples, while those who survived were too weak to resist the European domination.

For the first time indigenous Americans suffered the deadly Eurasian sicknesses of smallpox, measles, bubonic plague, cholera, typhoid, pleurisy, scarlet fever, diphtheria, mumps, whooping cough, colds, pneumonia, some unusual influenza and respiratory diseases, typhus, syphilis, malaria, yellow fever and dysentery[6]. All of these, apart from tuberculosis, came from the white man. The destructiveness of tuberculosis was largely due to conditions upon its advent. It is important to understand how disease was able to ‘melt down’[7] the population, killing more than 90% of the people[8]. Infectious diseases rely upon a transfer from the infected to susceptible in order to spread. Epidemics can be spread by contaminated food or water or directly from person to person through physical contact, saliva or blood. Disease-carrying animals, such as insects and rodents, are vectors that infect humans. After an epidemic has subsided, the affected host population contains a sufficiently small proportion of susceptible individuals that reintroduction of the infection will not result in a new epidemic. Following an epidemic, the host population often returns to susceptibility because of the deterioration of individual immunity, the removal of immune individuals by death and the birth of susceptible individuals. In time the population as a whole becomes susceptible. In consequence, the diseases came, spread and killed again and again throughout the Americas.

The most lethal pathogen the Europeans introduced was smallpox. Smallpox is an often fatal, highly contagious viral disease. It found millions of susceptible Amerindian hosts. Smallpox had a colossal mortality rate in natives experiencing it for first time. Immunity to the disease left the Europeans healthy and this further demoralised the natives. The smallpox virus is transmitted through droplets in the breath of an infected person that are inhaled by another person and this makes it highly infectious. Death is caused by infection of the lungs, heart, or brain. Male infertility, a side effect among survivors, affected population levels[9]. Survivors usually experience long-term immunity to the disease although they do not pass this to their children. All, or very nearly all Native Americans contracted smallpox in 1520-24. Spanish reports of 50% mortality were almost certainly underestimates[10]. Smallpox epidemics reoccurred more than 30 times between 1520 and 1900[11]. For example, the Florida Chiefdoms suffered an epidemic in 1655[12]. McNeil emphasises the importance of smallpox, writing: ‘It was clear that if smallpox had not come when it did, the Spanish victory could not have been achieved in Mexico’. Disease also had a huge effect in Peru, not least of all because the reigning Inca, his son and heir died, leaving no clear successor. Of equal significance is that although the Aztecs actually defeated Spanish attacking, on the same evening as the Aztecs drove the conquistadors from Mexico City, a smallpox epidemic broke out.

After smallpox, measles was the second pandemic. First breaking out in Cuba 1529. It killed two thirds of the Cuban population. Like smallpox it had existed in Europe and Africa for generations. Once again it found a 'virgin-soil' population, as those who had survived smallpox had no immunity to measles. It spread through political boundaries and past natural frontiers, reaching Florida in 1533. Like smallpox and influenza, measles was an airborne epidemic. Other diseases travelled by intermediate vectors such as lice, fleas and mosquitoes, which could transmit typhus and malaria, for example.  It is therefore no surprise that these diseases came later.

The reasons for the ‘holocaust’ were more complicated than just disease, there were a broader combination of factors. The events that occurred in the 'proto-historic' populations, (those that changed because European influences reached them through other Native American groups), should be considered if the significance of diseases is to be appreciated. The Europeans introduced technology and territorial alterations that ‘extended far beyond their own presence’[13].

When evaluating the role of disease in the devastation it is also important to stress that many factors would not have occurred were it not for the spread of disease. For example, the immense mortality from epidemics ‘profoundly influenced Native American mental health, affecting their energy and effectiveness’[14] and lead to suicides. It is debatable whether this constitutes a factor related to disease. One could define non-disease factors as everything apart from directly dying from disease. Alternatively, for example, starvation could be interpreted as a disease factor because it may be as a consequence of the disease. Many starved because all their family had died from the disease. Other factors which would not have occurred without the diseases included suicide and low vitality due to mental depression. Russell Thornton thought alcoholism was also an important cause, again as a link to disease[15].

The ‘Black Legend’ wrongly asserts it was primarily Spanish military superiority and hence non-disease factors that caused the decimation of the population.  Many historians have overplayed the importance of these non-disease factors. Revisionists branded Columbus as the ‘great Satan’, the European who orchestrated the ‘violent dispossession and destruction of the indigenous populations’[16]. There is little doubt that many soldiers were extremely cruel towards the native populations. McNeil called the Spanish ‘utterly ruthless’[17]. They had ‘more respect for their dogs’ than the Indians, their motto being 'the only good Indian is a dead one'[18]. The invaders saw the natives as vermin[19]. The natives were said to long for death to escape from the sadistic Spaniard, throwing themselves off cliffs and into rivers[20]. Spanish technology was vastly superior to that of the Old World where the wheel had not yet been invented. The Spanish had horses, armour, ships, metal, guns and hunting dogs. They also had more advanced communications, for example, writing. The claim that the Native Americans ‘thought the horse and rider were one, for they had never seen a horse before’[21]may be purely rumour but, if true, it demonstrates the impact of the invasion on the natives. Although there is little doubt the invaders used these advantages to treat the natives terribly, disease was by far the main factor in the population decline. The Black Legend alleges the Natives were hunted down by the Spanish, plundered and deprived of food. Advocates of the Black Legend claim millions died in the deadly mines, where they were forced to work in horrendous conditions. Nikolaus Federmann, a resident of Santo Domingo, Hispanola remarked ‘many died in the mines…because they are delicate people and poor workers’[22]. However, Federmann also stated far more people died of disease[23].

Similarly, warfare and genocide, the deliberate killing of a people, were not as important in the overall decline as the Black Legend claimed, although they were extremely important for particular tribes. Brooks thought war was the real catastrophe. In Texas there was blatant genocide of American Indians by non-Indians[24]. Thornton thought that American Indian war before 1492 had important effects on population, for example amongst the Mississippian groups[25]. The conflicts once the Europeans arrived were often extremely complicated due to alliances between American Indians and Europeans against other Europeans and/or Indians. Even the wars between the Europeans themselves proved costly to the Indians. The Mohawk King Hendrich stated in 1754 that the Europeans were ‘quarrelling about lands which belong to us, and their quarrel may end in our destruction’[26]. The number of American Indians killed by genocide can only be estimated, although it is a small amount compared to the disease. It is extremely difficult to estimate the losses from genocide due to the fact that it was not as well recorded as warfare. An example of genocide being confused with war was the 'battle' at Wounded Knee Creek in which hundreds of old men, women and children were massacred[27]. It was genocide not a battle.

There were many additional deaths from disease resultant from the way the natives reacted to the epidemics, which they did not understand due to a lack of experience. For example, they did not understand that contact with the smallpox virus is necessary for it to be passed on.  Customs that spread the disease included the trade between groups and the visiting of the ill by friends and relatives. Native Americans typically lacked the support services, like adequate nursing to cope with the epidemics. Their main method of curing people, making them ‘sweat it out’ proved useless against smallpox. These sweat baths followed by cold ones, which had been widely used to treat common American illnesses associated with fevers, proved ineffective (and possibly worsened the disease). When all members of a hunter-gathering family fell ill, nobody remained to ‘obtain key animal protein food[28]’ to boost resistance. Often there was no one to cook or even to obtain drinking water. Nor was anyone available to carry out the essential agricultural tasks. There were many deaths from starvation, as people had nobody left to care for them. W. George Lovell observed that ‘many died from plague and many others from hunger because everyone was too sick to provide for them’[29].

Wave after wave of epidemic disease psychologically overwhelmed the natives who interpreted them as divine retribution. They responded to the diseases in a very negative way, feeling betrayed by their Gods. Because the religious and political systems of the tribes were inextricably linked this caused political collapse and natives fled from their societies. The epidemics undermined the faith of many Native Americans in their ‘fundamental postulate[30]’ of ethnic superiority. Some natives joined the Europeans, hoping to right past wrongs or form part of a new ruling class. This would never have happened were it not for the disease. This loss of confidence made them more vulnerable to the Europeans. The ‘doom-ridden’ people had lost the will to live. The natives lamented 'we were born to die'. Parents allowed babies to die and suicide became commonplace. The natives lamented in a song:

             ‘We have seen bloodshed and pain where once we saw beauty and valour.

We are crushed to the ground; we lie in ruins.

There is nothing but grief and suffering in Mexico and Tlatelolco, where once we saw beauty     and valour’[31].

The influence of various non-disease factors can be seen in the defeat of the Aztecs. While Cortés had few followers in their heroic conquest of the Aztec empire they had great advantages and a lot of luck. Gunpowder, steel and horses easily impressed the technologically primitive natives. The Aztec’s thought Cortés was a reincarnation of their God whose return to them they one day expected. The fact the Aztecs themselves were a cruel and exploiting race meant their subjects were happy to welcome the new conquerors as liberators or at least as a change of masters. The Aztecs were hated by many of the tribes under their sovereignty, and some of these tribes became willing allies of Cortés[32]. Someone said ‘the key to the Spanish conquest of Mexico was the dissension among the different peoples of the Aztecs' subjugated empire’. The Aztecs had made no attempts to assimilate the cultures to their own and this proved the basis for the revolt against them Cortés incited. 

Despite the majority of Historians laying most of the blame for the demise of the Amerindian on microbes, the theory that Spanish cruelty was the primary factor in the collapse of native empires still persists. As Roberts says: ‘although circumstances thus favoured the Spanish in the end their own toughness, courage and ruthlessness were the decisive factors’[33]. Pizzaro’s conquest of Peru displayed even more terribly the brutality of the conquistadors. For example, in the capture of the Inca Atahuallpa, the Spaniards massacred 6,500 unprepared Indians[34].

  From the 1960s into the late 1980s, Marxist or neo-Marxist students focused on the issue of exploitation as the key to European control of native peoples and the resultant native deaths. Indeed, T.S Floyd at the time said that 'the issue of Spanish cruelty to the Indian seems to have acquired even more distortion in recent years than it commonly carried, having become entangled with racism, modern ideas of liberty, and other notions inappropriate to the historical context’[35]. It is important that the Black Legend originated as part of the protestant anti-Catholic propaganda of the16th century.

Noble David Cook has dismissed the Black Legend as ‘uniformed debate resulted from incomplete information[36]’. Crosby said the Europeans had not the time in which to destroy the natives. It was probably in Spanish interests to maintain a native population that could deliver optimal productivity for example, in mining. The fact that the population was probably much lower than the optimal suggests that factors beyond the Spaniards control that led to the decline. However, advocates of the Black Legend believe they tried to wipe out the ‘execrable race[37]’ completely. Whitmore claimed that the Black Legend and in fact all non-disease factors could be discounted as epidemic disease alone could account for the mortality[38]. Spanish exploitation was significant but not the major factor.

McNeil accused other Historians of neglecting the historical significance of disease. The Indians fell to McNeil's law of biological aggression. He proposed that throughout history expanding groups have aggressively exerted an advantage over a previously independent, isolated people. This is precisely what happened in the Americas. The fate of the Aztecs demonstrates that disease was more important than armed combat in the population decline. Neither the obvious technical superiority of the Spaniards and the superstitions that Quetzalcoatl or other gods would destroy the natives, nor the Spaniards' alliances with tribes subjugated by the Aztecs or Incas accounts for the totality of Spanish victory. McNeil claims that once the Aztecs decided to fight, they savagely attacked and defeated the Spanish[39]. On the very evening that the Aztecs drove the conquistadors out of what is now Mexico City, killing many while routing the rest, a smallpox epidemic began. There were too few Spaniards to have killed the millions of natives that died[40]. It beggars belief that Cortés and Pizarro defeated an empire of millions with only hundreds of soldiers. Disease, rather than the Spanish defeated the Aztecs. The consensus among modern historians is that disease was more important than all the other causes combined. Cook is one of the many Historians to argue that the disaster, rather than a deliberate plot of the Spanish, a deadly result of Old World bacteria infecting new, vulnerable populations. Thornton said disease was ‘without doubt’[41] the most important single factor in American Indian population decline, although he acknowledged there were ‘other important factors’[42]. Disease coupled with human behaviour played the main role in the conquest of the Americas by the Europeans, rather than the so-called  ‘Black Legend’. Cook concludes: ‘disease, not war, was primarily responsible for the rapid expansion of the Spanish Empire’[43] in the Americas or as Karlen writes of the conquistadors ‘'Their strongest ally was the pale Fourth Horseman of death[44]’. 

Bibliography

• D. Arnold, The Problem of Nature: Environment, Culture and European Expansion 1996, Hartnolls Limited, Bodmin, Cornwall

• Cook, Nobel David, Born to Die: Disease and the New World Conquest 1492-1650, 1998, Cambridge University Press

• A.W Crosby, The Columbian voyages, the Columbian exchange, and their historians, Washington, c1987.

• S.D. White, From Cortés to Castro: an introduction to the History of Latin America, 1492-1973, London, 1974

• A. W. Crosby, Ecological Imperialism: The Biological Expansion of Europe

• J. Diamond, Guns, Germs and Steel: The Fates of Human Societies, ch. 11

• H.F. Dobyns, Their number become thinned: Native American population dynamics in eastern North America, 1st edition, Knoxville, 1985.

• A. Karlen, Plague’s Progress: A social History of Man and Disease, Great Britain, 1995.

• W.H.McNeil, The Rise of the West: A History of the human community, London and Chicago, 1963.

• A.F. Ramenofsky, Vectors of death: the archaeology of European contact,  1^st edition, University of New Mexico Press, c1987.

• J. M. Roberts, The Penguin History of the World, 3rd edition, Penguin Books, 1995.

• R. Thornton, American Indian holocaust and survival: a population history since 1492, University of Oklahoma Press, 1987

• http://falcon.cc.ukans.edu/~lskinner/peru.html

• http://www.amazon.com/ - Plagues and Peoples by McNeil (1976) chapter one

• http://www.tcr.org/mexico.html Concorde review web page: End of an empire: The Spanish conquest of Mexico by Ben Hulse

• http://www.eb.com/ Britanninica Encyclopaedia on-line

• http://www.umt.edu/nas University of  New Mexico Native American Studies

Encarta 2000 CD-ROM articles on: Peru, Cortes, Pizzaro, Smallpox, Epidemics, Christopher Columbus.