Was a salmonella outbreak responsible for ending the Aztec civilization?

Did A Salmonella Outbreak Cause Aztec Society To Collapse?

Aztec society perished for a number of reasons, but new evidence is now pointing to a deadly outbreak of salmonella as very possibly being the main culprit responsible for the demise of the Aztecs. In 1519, Spanish forces arrived in Mexico, and the Aztec population was then estimated to be at 25 million. In the century that followed, Aztec society had dwindled to just 1 million people.

Scientists have now put forward fresh evidence from the DNA of a bacterial species, suggesting that a deadly salmonella outbreak may have been responsible for the death of Aztec society.

Science Alert reports that after the Spanish arrived in Mexico, there were a number of forces at play that would have affected the Aztecs. One of these includes the fact that Spaniards brought with them a number of European diseases, which caused outbreaks in the native population and which the Aztecs would not have built up a resistance to. The worst out of all of these outbreaks was called cocoliztli, which is from the word “pestilence” in Nahuatl, the Aztec language.

An Aztec calendar of the sun made out of stone at the National Museum in 1930.
An Aztec calendar of the sun made out of stone at the National Museum in 1930. [Image by Ewing Galloway/Getty Images]

Scientists working at the Max Planck Institute for the Science of Human History in Germany described in a paper how cocoliztli was responsible for wiping out 80 percent of the Aztec population between the years 1545 and 1550.

“The 1545 cocoliztli epidemic is regarded as one of the most devastating epidemics in New World history.”

Previously, scientists have attributed what was called cocoliztli to a variety of different diseases, including smallpox, measles, or typhus. In 2002, one paper noted that it may have even been a viral haemorrhagic fever. This, combined with a severe drought, was said to have been another possible reason that the Aztecs disappeared. But up until now, there has been no solid DNA evidence to concretely prove any hypothesis.

To show that salmonella may have actually been responsible for killing off 80 percent of the Aztec population, scientists from Max Planck chose to examine a burial ground out in the Oaxacan highlands of Mexico. They used this burial site to painstakingly extract the DNA contained in the teeth of 29 people who were buried here, with 24 out of the 29 people buried having died from the cocoliztli epidemic.

After the scientists compared their DNA results with 2,700 more modern bacterial genomes, they discovered that a few of the Aztec people they had tested had been infected with a severe strain of salmonella, which is known as Salmonella paratyphi C.

While this particular strain of salmonella is quite rare in most areas of the world, it still affects those in developing parts of the world. This severe strain of salmonella is spread due to fecal matter and results in a typhus-like sickness that causes what is known as enteric fever. Ten to 15 percent of those infected will die if they do not receive the proper medication and treatment.

Because of their DNA research from the burial ground in Mexico, Max Planck researchers have concluded that the Aztec population may have been virtually wiped out due to a salmonella outbreak.

“We propose that S. Paratyphi C contributed to the population decline during the 1545 cocoliztli outbreak in Mexico.”

Mexicans climbing Aztec pyramids in Teotihuacan, Mexico on March 21, 2003.
Mexicans climbing Aztec pyramids in Teotihuacan, Mexico, on March 21, 2003. [Image by Susana Gonzalez/Getty Images]

The Natural History Museum of Denmark’s Hannes Schroeder, who is another DNA researcher, thinks that the Max Planck scientists have made an extremely good case with their study.

“It’s a super-cool study. They make a really good case.”

It is important to note that this study linking a deadly salmonella outbreak to the collapse of Aztec civilization has not been peer-reviewed yet, but that will be happening soon.

Once this new Max Planck study is peer-reviewed, do you think that the DNA results linking salmonella to the deaths of 80 percent of the Aztec population will be confirmed?

[Featured Image by Hulton Archive/Getty Images]

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