Syphilis, one of the oldest known sexually transmitted diseases, continues to spark intense debate among scientists about its exact origins. A recent study, carried out by researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig and published in Nature, provides crucial new data thanks to the genetic analysis of ancient genomes found in America. This work questions established historical hypotheses, particularly on the role of transatlantic travel in the spread of the disease.
By analyzing skeletons dating back several millennia, the team was able to trace the evolution of the pathogen responsible, Treponema pallidum. This research goes beyond strictly medical issues to shed light on the dynamics of transmission between continents, in a context marked by colonization and intercontinental exchanges. A discovery that profoundly revisits our understanding of the history of this infection.
American origins of syphilis, confirmed by ancient genomes
The researchers focused on human bones from South and Central America, dated using carbon-14. These remains, collected in Argentina, Chile, Mexico and Peru, presented lesions characteristic of infections with Treponema pallidum. This is the group of bacteria responsible for diseases such as syphilis, yaws and bejel. The team used advanced genetic reconstruction techniques to piece together five ancient genomes of this pathogen group. These genomes revealed that these bacteria share a common ancestry dating back about 9,000 years. At that time American populations found themselves biologically and geographically isolated. This indicates that these pathogens must have already been present in America well before contact with Europeans. Which would confirm a local origin of these diseases.
Additionally, the study highlights significant genetic diversity among bacterial strains found in America. It actually indicates a long evolution on this continent before their global diffusion. “ These data support an American origin for these pathogens and call into question certain historical theories “, says Kirsten Bos. This diversity contrasts with modern forms of these diseases, which are now more homogeneous. She highlights the impact of European colonialism on their spread. Indeed, researchers believe that the arrival of Europeans contributed to the transformation of local pathogens into global infectious agents. This marked a turning point in the epidemiological history of syphilis and its related diseases. Now let's see how it arrived on the European continent.
A spread accelerated by European colonialism
The genetic data from this study confirm that the pathogens responsible for syphilis, present in America before the 15th century, were introduced to Europe following the expeditions of Christopher Columbus. This introduction led to a significant epidemic in 1495, in the military camps of Charles VIII in Italy. The disease, then unknown, caused devastating symptoms, including severe skin lesions and bone deformities. It then led to strong stigmatization of infected people. These historical events are consistent with the results of the analysis of ancient genomes. They demonstrated that modern forms of Treponema pallidum emerged after this period. A testimony to the rapid adaptation of the pathogen in a new epidemiological context.
The study also highlights the impact of European colonization and human trafficking networks on the global spread. “ While the ancient forms circulated locally in America, it was the Europeans who allowed their global dispersal », explains Rodrigo Barquera. Transatlantic trade and population movements, often forced, have transformed a disease previously confined to certain regions into a global pandemic. This dynamic is reinforced by genetic data. They reveal a homogenization of the strains after this period, reflecting their large-scale expansion.
Questions still unanswered for syphilis
Despite progress made in understanding the origins of syphilis, certain uncertainties remain. Identification of bone lesions similar to those caused by Treponema pallidum on European human remains before 1492 questions current hypotheses. These findings suggest that related pathogens may have been circulating in Eurasia long before Columbus returned. If these lesions do not alone confirm the presence of syphilis in Europe, they open the way to questions about possible pre-Columbian exchanges between the continents. Perhaps there were archaic forms of the pathogen that evolved independently in different regions of the world? These hypotheses underline the importance of genetic analyzes to decide between an exclusively American origin or an older co-evolution of the pathogen in several geographical areas.
Ancient genetic data collected in America also reveal a remarkable diversity of strains of Treponema pallidumnow extinct. Which obviously complicates the interpretation of the results. This diversity could reflect evolutionary dynamics specific to the American continent. Pathogens are believed to have evolved in geographic isolation for millennia. “ We still have a lot to learn », explains Johannes Krause. Future studies could find genetic traces of extinct strains, essential to understanding the full history of the pathogen. The results therefore assume that now extinct strains could have circulated globally. They would have potentially influenced human populations well before the documented exchanges of the modern era.
Understanding ancient origins to anticipate global health challenges
This scientific advance illustrates the power of genetic analyzes to revisit complex and multidimensional historical episodes. The work of the Max Planck Institute, by revealing the American origin of syphilis and tracing its global spread, provides crucial insight into the interaction between diseases and human societies. However, other studies enrich this perspective, notably those published by a team from the University of Basel and Zurich. She identified traces of syphilis-like infections on human bones in Brazil dating back 2,000 years. This research, published in Natureconfirms that treponematoses were already widespread among pre-Columbian populations. Long before the arrival of Christopher Columbus.
These discoveries push the boundaries of our understanding of ancient pathogens. They open the way to new questions on the evolution and dispersal of infectious diseases. As science continues to shed light on these puzzles, these studies highlight the importance of understanding the past to better anticipate future global health challenges. As more advanced technologies emerge, they will allow the evolutionary history of diseases like syphilis to be traced even more precisely, strengthening the inseparable link between historical research and medical progress.
Source: Barquera, R., Sitter, TL, Kirkpatrick, CL et al. “Ancient genomes reveal a deep history of treponemal disease in the Americas”. Nature (2024).
With an unwavering passion for local news, Christopher leads our editorial team with integrity and dedication. With over 20 years’ experience, he is the backbone of Wouldsayso, ensuring that we stay true to our mission to inform.
