History in the News
Scientists have sunk their teeth into new DNA analysis to explain how millions perished
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From 1545-50, the Aztecs fell prey to one of history’s deadliest epidemics. It began with blemishes or rashes on the skin, fevers, headaches and vomiting, before victims started bleeding from the mouth, nose and eyes. Death followed within days. The mysterious disease, named by the Aztecs as cocoliztli (‘pestilence’), killed as many as 15 million people, or 80 per cent of the population.
It was only one of the outbreaks to obliterate the Aztec Empire since the arrival of Hernán Cortés in 1519, but the exact cause has never been determined. A new study, published in the scientific journal Nature Ecology and Evolution, may reveal a significant clue, though.
Scientists found traces of the bacterium Salmonella enterica, which can cause fevers such as typhoid, in DNA extracted from the teeth of 29 skeletons buried in southern Mexico. It is the first direct evidence pointing to a specific cause.
The team – comprised of researchers from the Max Planck Institute for the Science of Human History, Harvard University and the Mexican National Institute of Anthropology and History – used an advanced screening technique, called MALT. This allowed them to test for any known pathogen, rather than testing for each individually.
“This is a critical advancement in the methods available to us as researchers of ancient diseases,” said Kirsten Bos, a member of the team. “We can now look for the molecular traces of many infectious agents in the archaeological record.”
While more research is needed, and salmonella cannot conclusively be said to be the sole culprit, the findings are a compelling piece to the puzzle.
CURSE OF CORTÉS Posthumous dental work has shed light on the deadly outbreak, one of many to plague the Aztecs after the arrival of Hernán Cortés ( below)