A sickness spread out through the once-mighty Aztec Empire and killed 15 million people in the span of just five years. What exactly caused the death of 80% of this population?
The Aztec culture was once a thriving one. [Mural by Diego Rivera]
The Aztecs was a thriving Mesoamerican culture that boasted a magnificent empire and built great cities. However, even the greatest of human civilizations aren’t immune to disasters and plagues. From the year 1545 to 1550, the Aztecs in what is now southern Mexico suffered what they called cocoliztli, which means “pestilence” in the Nahuatl language. The afflicted came down with high fevers, suffered headaches, and bled from the eyes, ears, and nose. Indigenous as well as Spanish artists depicted people bleeding from the nose and coughing up blood.
It took only three to four days for death to follow. A second cocoliztli, which took place from 1576 to 1578, decimated half of the remaining population. The first cocoliztli came just a couple of decades after a smallpox outbreak that killed five to eight people after the Spaniards invaded.
A depiction of the smallpox epidemic among Aztecs [Scanned from Viruses, Plagues, and History: Past, Present and Future (2009)]
Scientists, archaeologists, and historians have long speculated on what cocoliztli was exactly, and many have thought that it may have been a blood-borne disease. A new study, however, offers clearer insight into what decimated a once-great civilization.
Though art from the period depicted how the sickness manifested in humans, it was still not enough information to draw scientific conclusions from. There was still a lack of physical evidence, since most diseases don’t leave visible traces on the skeletons of the afflicted. Thus, researchers decided to examine 500-year-old DNA on the teeth of 24 indigenous individuals. The researchers analyzed the samples using a computational program called MALT, which stores information on all known causes of diseases.
The results showed that 10 of the 24 individuals had signs that they were afflicted with salmonella. Researchers also tested individuals who died before Europeans arrived. These individuals showed no signs of salmonella.
Is it possible that European invaders were to blame? A previous study found that this same strain of salmonella was found in the remains of a Norwegian woman who died in 1200. Thus, the same specific strain that nearly wiped out the entire Aztec population in the 16th century had already been present in Europe as early as the beginning of the 13th century.
How did the arrival of Spaniards and other Europeans impact the health of indigenous American populations? [Illustration by Roberto Cueva del Río]
Historical records show that European invaders and settlers brought infectious diseases to the Americas, such as smallpox and measles. These diseases were often much more deadly to indigenous people, since they didn’t have sufficient immunity to such infections. While it’s still possible that the specific salmonella strain that caused cocoliztli was already present in ancient Mexico, there’s no evidence that this is true.
Researchers also still have yet to confirm that salmonella was indeed the cause of the cocoliztli, since they have yet to test the remains found in other sites. It’s also possible that the Europeans weren’t entirely to blame, since there could have been a lot of factors that contributed to the pestilence. More cocoliztli sites would need to be examined to make these uncertainties certain.
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