Smallpox is a relatively old disease. Only recently has it been considered under control.

figure 2:

Ramses V c.1000bce. Spots on mummified remains of face believed to be smallpox.

old world

The disease is at least 3000 years old, confirmed in China and India, with a few isolated cases in North Africa.

There is no mention in Europe until the 6th century.

During the 17th and 18th Centuries smallpox was the most serious infectious disease in The West and accounted for a substantial proportion of deaths, especially among town dwellers. The mortality rate varied regionally, with 10% in Europe and 90% in America. During the 20th Century there was recognised for the first time a milder form of smallpox, called variola minor or alastrim, with a consistently low mortality rate of the order of 1%. This disease was endemic in Britain until 1935. Still more recently there has been recognised a third form, named East African Smallpox, the mortality rate of which in uncaccinated subjects is about 5%. This has not been recognised as having occurred in The West.

The Plague - a different disease than smallpox: a bacteria spread by rats - had eliminated as much as a third of the European population over a five year period. Smallpox was never that devastating in Europe, becoming endemic and occasionally outbreaking. Widespread resistance reduced the losses to local impacts of about 10%. However, introduction of smallpox to America quite rapidly depleted the population. For example, the Spanish attempted to settle Hispanola for sugar cane plantation in 1509. By 1518 every single one of the estimated 2.5 million aboriginals had perished, and the labour population had to be restored with African slaves.

figure 3:

Death rides a pale horse.

The death of Queen Anne's only child changed the line of British succession, and emphasized in England the importance of controlling this type of natural factor in an effort to protect political and economic stability. The inoculation of populations in England was widespread and is likely to have contributed to its unique population boost at the end of the 18th and through the 19th centuries.

figure 4:

Cortes is met by Aztecs.

america

Hispanola (modern Haiti and the Dominican Republic) were the first site of European contact. Exposure to smallpox during early Spanish attempts to convert the population into plantation slavery exterminated all 2.5 million inhabitants. They were replaced by African slaves, and this process was repeated throughout the New World for decades to varying degrees.

It is important to note at this point, though, that while smallpox is the only verfied culprit for this massive, early, dieoff, that it was probably due to a combination of many Old World illnesses introduced in this initial period of contact. They would include yellow fever, malaria, and polio. Smallpox probably caused the overwhelming majority of deaths, though.

Additionally, it should be noted that many regions of the New World were already underpopulated, since the post-Mayan civilizations of the Aztecs and Incas were in population decline due to a variety of factors, ranging from warfare to agricultural devastation. Certainly, disease could not have happened at a worse time.

For those readers who may be interested, there are two good references on this topic: Jared Diamond's Pulitzer winning Guns, Germs, and Steel and William H. McNeill's Plagues and Peoples. These authors investigate the natural question of why European diseases so utterly devastated Amerinds, but no American diseases seriously threatened Europe's populations.

figure 5:

Things don't go as well as planned.

Cortes introduced smallpox in 1520 during his unsuccessful assault on Techotitlan, the Aztec capital, now Mexico City. He had retreated to the coast and was surprised to find no retribution force following. After a few months he sent spies to the capital who reported widespread smallpox, and he returned to conquer the Aztecs in a matter of a few weeks, and established himself as their new god and emperor. The Aztecs, possibly originally as numerous as 20 million, were thus subjugated to Spain by Cortes' 300 conquistadors.

Historians agree that this introduction was accidental. One of Cortes' crewmembers, who had recently visited Africa and had become infected, was captured and retained in the capital as a hostage.

Pizarro's conquest of the Incas was also assisted by population decline.

The role of disease in American conquest was threefold: firstly, it reduced the fighting capability of the Aztec and Incan armies as they became sick and died. Secondly, the deaths of their heads of political leadership left power vacuums, and much of the attention of vassal leaders was occupied with civil wars. The conquistadors played factions against each other. Thirdly, the prevailing beliefs of these cultures led them to believe that the European forces were employing supernatural powers, and many miltary leaders decided to either join the conquistadors, or flee, rather than fight them. Consequently, resistance was weak, disorganized, and usually nonexistant.

figure 6:

Smallpox strikes Tenochtitlan.

The conquest of the continent was very much facilitated by rapid population declines. The history of early settlement was typically one of European settlers moving into an area, fighting aboriginals and over time, finding less and less resistance. The Aztec, Huron, Iroquois, Mohigan and other major nations with populations in the millions were reduced to thousands or eliminated altogether, mostly by smallpox.

Historians disagree on the total New World population at the time of Contact. The highest estimates are around 80 million. The most convincing estimates are between 20-30 million. Regardless, by the end of the 16th century, credible estimates put a survivor population at just over 1 million.

Another contentious historical event was a deliberate attempt to infect North American tribes by providing blankets which had been contaminated with pus from smallpox scabs.