Syphilis originated in the Americas, ancient DNA shows, but European colonialism spread it widely

The outbreak of a mysterious disease ravaged Europe in the late 15th century, shortly after Christopher Columbus and his crew returned from the Americas. Experts have debated for centuries where this malady — now known as syphilis — originated. Now, new research into ancient genomes has finally provided an answer: It turns out, syphilis came from the Americas, not Europe.

"The data clearly support a root in the Americas for syphilis and its known relatives," study co-author Kirsten Bos, an archaeogeneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, said in a statement. "Their introduction to Europe starting in the late 15th century is most consistent with the data."

The researchers analyzed human skeletons from numerous archaeological sites in the Americas for evidence of syphilis and related diseases. They revealed their findings in a study published Dec. 18 in the journal Nature.

Bacteria in the genus Treponema cause the non-venereal diseases pinta, bejel and yaws in addition to venereal syphilis, and these are collectively known as treponemal diseases. All of these diseases can cause the destruction and remodeling of bone during a person's life, so archaeologists have long investigated pre-Columbian skeletons in the Americas for clues to the origin of syphilis.

But clear genetic evidence of syphilis has been more difficult to find because of the poor preservation of treponemal DNA over the centuries.

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"We've known for some time that syphilis-like infections occurred in the Americas for millennia, but from the lesions alone it's impossible to fully characterize the disease," study co-author Casey Kirkpatrick, a postdoctoral researcher at Max Planck, said in the statement.

In the new study, the researchers took samples from the teeth and bones of dozens of skeletons from the Americas that showed signs of a treponemal infection. Then, thanks to advances in genomic technology, they were able to isolate Treponema pallidum genomes from the skeletons of five people who died in what are now Mexico, Peru, Argentina and Chile before 1492.

Based on their genomic analysis, the researchers found that T. pallidum, the bacterium that causes syphilis and related diseases, originated in the Americas during the middle Holocene epoch, as far back as 9,000 years ago, and then split off into the subspecies that cause the various treponemal diseases.

But modern syphilis may have cropped up just before the arrival of Columbus, the scientists wrote in the study, and rapidly expanded in the early colonial period corresponding with the rise in transatlantic human trafficking.

"While indigenous American groups harboured early forms of these diseases, Europeans were instrumental in spreading them around the world," Bos said in the statement.