Ancient DNA Reveals Syphilis Origins Extend Back 5,500 Years

Recent research has uncovered that the origins of syphilis date back much further than previously believed. An international team led by anthropologist Elizabeth Nelson from Southern Methodist University has identified a 5,500-year-old Treponema pallidum genome in a burial site in Colombia. This finding challenges the long-held belief that the disease first entered Europe during the 1495 siege of Naples, which resulted in the first major outbreak of syphilis in Europe.

The narrative surrounding syphilis has often linked its emergence to the army of King Charles VIII of France, whose troops, consisting of around 20,000 mercenaries, were implicated in the spread of the disease. Historical accounts describe the chaotic conditions in Naples, a city known for its culture of indulgence, as the perfect breeding ground for such a sexually transmitted infection. Chroniclers documented the soldiers’ rampant behavior, which involved extensive interactions with sex workers and rampant debauchery.

Upon the army’s return home, many of these mercenaries carried the disease across Europe, sparking a series of outbreaks. The stigma attached to syphilis led to a blame game among nations, with the French referring to it as the Neapolitan disease and the Neapolitans calling it Morbus Gallicus, or the French disease. The English also labeled it the French Pox, creating a complex web of cultural attributions surrounding the illness.

While the siege of Naples is often seen as the pivotal moment for syphilis in Europe, Nelson and her colleagues’ discovery suggests a much older and more complex history. The team uncovered the ancient genome during a broader research project examining the population history of the Americas. The individual from whom the genome was extracted, labeled TE1-3, lived as a hunter-gatherer around 5,500 years ago in the Tequendama I rock shelter in Colombia.

Unraveling the Pathogen’s History

The research team focused on sequencing the DNA of this ancient individual, which yielded unexpected results. Despite no visible signs of treponematosis on the skeleton, the analysis produced a significant volume of data, allowing for the identification of Treponema pallidum. The genome revealed that this ancient strain diverged from the modern subspecies responsible for syphilis, bejel, and yaws approximately 13,700 years ago.

According to Nasreen Broomandkhoshbacht, a geneticist at the University of Vermont and co-author of the study, their original aim was not to explore the origins of syphilis. “We weren’t looking for the origins of syphilis; this wasn’t the main focus of our research,” she explained. The findings indicate that the Treponema lineage was likely far more diverse and widespread than previously thought, suggesting a long-standing relationship between humans and these pathogens that may have existed long before the infamous outbreaks in Europe.

The discovery also raises questions about the evolution of Treponema pallidum’s mode of transmission. The team notes that understanding how and when sexual transmission became prominent in this lineage is crucial, particularly in relation to the pandemic in Naples.

Broader Implications for Disease History

While the 1495 outbreak is significant, it appears to be just one chapter in a much longer history of human interaction with Treponema pathogens. The current research underscores the need for more extensive studies that could reveal additional ancient genomes from different geographical locations and social contexts. By examining populations such as hunter-gatherers, farmers, and urban dwellers, researchers hope to gain insight into the ecological and evolutionary dynamics that shaped the spread of this disease.

Despite the richness of their findings, Davide Bozzi, a computational biologist at the University of Lausanne and lead author of the study, cautions that current data limits their understanding of the ancient pathogen’s virulence and symptoms. “With the data we have today, we can’t say anything about the virulence of this ancient Treponema pallidum subspecies, about how the symptoms of the disease it caused looked like, or about its mode of transmission,” he noted.

As the team continues to investigate these ancient pathogens, their work may reshape our understanding of syphilis and its origins, highlighting the complexity of disease transmission and the long history of human health. The integration of genetic data with archaeological findings opens new avenues for research that could ultimately provide a more nuanced understanding of how diseases evolve and spread across cultures and time.