A new study published in the journal Nature provides compelling evidence that syphilis originated in the Americas and spread globally through European colonization, challenging long-held historical theories about the disease's origins. An international team studied ancient DNA harvested from lesion-ridden bones and teeth of five individuals who lived in Peru, Chile, Argentina, and Mexico before or around the time of Christopher Columbus.
"We were able to reconstruct five genomes from these bones and we see that they are sister lineages to the modern strains of the bacterium that is circulating in humans today," stated Kirsten Bos, group leader for molecular paleopathology at the Max Planck Institute for Evolutionary Anthropology and one of the leaders of the work, stated, according to The Guardian.
"We see extinct sister lineages for all known forms of this disease family, which means syphilis, yaws, and bejel are the modern legacies of pathogens that once circulated in the Americas," said Rodrigo Barquera, a postdoctoral researcher who contributed to the study, as reported by Phys.org.
The findings support the theory that syphilis was brought to Europe from the Americas following the voyages of Christopher Columbus. Bos argued the new evidence would settle the matter, stating, that "it's a very clear slam dunk: Okay, this clearly came from the Americas. They all appear to have emerged in the Americas," as noted in The Guardian.
The debate about the origins of syphilis is unlikely to be settled completely by this study. "I don't think we're solving the mystery necessarily, because there are still so many important questions we have to answer," Bos said, according to The Guardian. She added, "I think the narrative will continue to be debated," she added.
The research team used ancient genomic data to estimate that the most recent ancestor of Treponema pallidum, the bacterium that causes syphilis and related diseases, emerged approximately 8,000 years ago, suggesting that treponemal diseases may have always been present as humans migrated from Asia to the Americas, as reported by The Washington Post. The study found that early versions of T. pallidum were already diverse and widespread in the Americas before European contact.
After Columbus returned from his voyage to the Americas, syphilis first erupted in Europe in 1495, shortly after the French King Charles VIII invaded Italy in 1494. An unknown and disfiguring disease began to sweep across Europe, causing pustules and sores to erupt on people's bodies and faces. The epidemic that followed Charles VIII's invasion is regarded as the first historical account of syphilis.
Despite this, some scholars believe that syphilis was present in Europe before Columbus set sail. European skeletons have been unearthed with bone-scarring that resembles syphilis, and many of these skeletons predate 1492, according to The Washington Post. "The simple narrative of the Columbian theory starts to unravel when experts examine lesions seen in bones from Medieval Europe," as reported by Phys.org.
Anne Stone, an anthropological geneticist at Arizona State University, said the new study featuring ancient genomes is especially exciting, though the results also raise new puzzles. She questioned whether the date of the bacterium's emergence might get pushed back as more ancient genomes are found. "Much of the world is a black box with a lack of samples to say whether the disease existed or not," Stone observed, according to The Washington Post.
"This paper, by being able to anchor when and where it emerged, is going to be fundamental in improving our basic knowledge of syphilis, and therefore act as building a foundation for additional work," stated Molly Zuckerman, a paleopathologist at Mississippi State University, as reported by The Washington Post.
The study underscores the challenges in tracing the origins of diseases that have evolved and spread over millennia. Mathew Beale, a senior staff scientist who studies bacterial evolutionary genetics at the Wellcome Sanger Institute, wrote, "As is so often the case in science, the story is likely far from settled: It is plausible that each set of new genomes will change things, repeatedly reopening the story," according to The Washington Post.
Syphilis, caused by Treponema pallidum, remains a public health threat today. Despite being easily cured with antibiotics, there are more than 8 million new infections of syphilis each year globally, primarily due to sexual transmission, as reported by Deutsche Welle. Kerttu Majander, an archaeogeneticist at the University of Basel, noted "[the study shows] that syphilis has the capability of adapting to any environment. It raises the question whether other treponemal diseases existed before, and whether new, more aggressive diseases could emerge in the future," according to Deutsche Welle.
The article was written with the assistance of a news analysis system.