Ancient teeth hold clues to one of history's worst plagues

A mysterious illness that devastated native civilizations in the 1500s may have been identified, according to a paper published Monday in Nature Ecology and Evolution. “In less than a century, the number of people living in Mexico fell from an estimated 20 million to 2 million,” writes The Atlantic’s Sarah Zhang. The researchers found DNA from Salmonella enterica, which causes paratyphoid fever, in the teeth of 11 people.

Why it matters: Some scholars believe such plagues made it easier for the Spanish and English to conquer the complex, sophisticated nations that existed in the Americas before Columbus’ arrival. European colonists brought dozens of diseases to the Americas (and brought a smaller number back to Europe). Since native populations had no immunities, the pathogens swept through towns, killing millions long before the colonists themselves arrived.