It’s long been taken for granted that the Spaniards killed millions of Aztecs by introducing Old world diseases to the New World. Mexican epidemiologist Rodolfo Acuña-Soto, a dogged Mexican epidemiologist has found evidence that a native disease was the culprit. Discover.Com has publshed a fascinating article about Acuña-Soto’s research. It begins with a precis of the received wisdom:

When Hernando Cortés and his Spanish army of fewer than a thousand men stormed into Mexico in 1519, the native population numbered about 22 million. By the end of the century, following a series of devastating epidemics, only 2 million people remained. Even compared with the casualties of the Black Death, the mortality rate was extraordinarily high. Mexican epidemiologist Rodolfo Acuña-Soto refers to it as the time of “megadeath.” The toll forever altered the culture of Mesoamerica and branded the Spanish as the worst kind of conquerors, those from foreign lands who kill with their microbes as well as their swords.

But there were wholes in the story. For starters, the Aztecs had a word for Smallpox that pre-dated the Spanish invasion and a different word for the plagues that wiped out so many millions. By researching Axtec records, Spanish archives and climate data preserved in tree rings, Acuña-Soto found the culprit:

Hemorrhagic viruses affect human populations that are already stressed, Acuña-Soto says. “The natives were poor and probably near starvation and living in unsanitary conditions where the rats would congregate. They also worked in the fields, where they’d be exposed to the rat droppings. The Spanish made up the upper classes.”

Cortés and his soldiers defeated, enslaved, and murdered the Aztecs, but now it seems that cocolitzli, a disease brought about by a native virus, is what really finished them off. Today the Aztec kingdom exists only in museums and ruins, but the virus could still be out there. As Mexico enters into yet another period of severe drought, could the killer reemerge?

This is not to excuse the Spanish for what they did, but genocide by disease should be dropped from the rap sheet.

HT Marginal revolution.