Ancient Skeletons Challenge Assumptions About Syphilis Origins
A new study suggests that congenital transmission of treponemal diseases may not be exclusive to venereal syphilis, challenging a long-held assumption in the field of archaeology.
The discovery of 3,500-year-old skeletons in Vietnam is challenging what scientists thought they knew about syphilis. The skeletons show evidence of congenital treponematosis, a group of diseases that includes syphilis, yaws, and endemic syphilis.
## Ancient Remains Reveal Congenital Treponemal Disease
The study, published in the *International Journal of Osteoarchaeology*, identified three children whose teeth and bones showed clear evidence of congenital treponematosis. The researchers analyzed skeletal remains from archaeological sites in northern and southern Vietnam dating to approximately 4,000 to 3,200 years ago.
The study's lead author, Dr. Melandri Vlok, said that for decades, congenital infection in archaeological remains has often been taken as strong evidence of venereal syphilis. However, the new research shows that this assumption may not always hold true. Other treponemal diseases may also have been transmitted from mother to child.
## Disease Signs Found in Ancient Children
The researchers examined 309 individuals from 16 archaeological sites across Vietnam, covering a period from 10,000 to 1,000 years before the present time. Only three young children showed diagnostic signs of congenital treponematosis. Their remains contained distinctive dental abnormalities and skeletal lesions associated with treponemal infection dating back at least 3,500 years.
The age distribution of infections at Man Bac, an archaeological site in northern Vietnam, is especially important. Most cases occurred among children and adolescents, a pattern more consistent with nonvenereal treponemal diseases that spread through skin contact rather than sexual activity.
## What the Discovery Means for Syphilis History
The findings could have important consequences for one of the longest-running questions in medical history: the origin of syphilis. Scientists studying ancient human remains have frequently used evidence of congenital infection when debating whether syphilis was present outside the Americas before the voyages of Christopher Columbus.
However, the new research indicates that congenital infection by itself may not be enough to distinguish venereal syphilis from other diseases caused by related treponemal bacteria. The study's lead author, Dr. Melandri Vlok, said that if congenital transmission can occur in non-venereal treponematoses, then we need to rethink how we interpret skeletal evidence in the past.
## Ancient DNA Presents Major Challenges
The research also highlights some of the difficulties scientists face when investigating ancient infectious diseases. In tropical regions such as Southeast Asia, ancient DNA is often extremely poorly preserved. That makes it especially difficult to use genetic evidence to determine exactly which disease affected ancient populations.
Researchers must also navigate rapidly changing ethical standards surrounding destructive sampling of human remains. The co-lead author, Ms Minh Tran, said that future research must move in new directions working in genuine partnership with communities connected to these remains, considering preservation before any biomolecular work begins.
## Rethinking the Evolution of Treponemal Diseases
The discovery also demonstrates the remarkable adaptability of *Treponema pallidum*, the bacterium responsible for treponemal diseases. Rather than concentrating only on determining where syphilis originated, the team says future studies should examine how different treponemal diseases evolved alongside human populations, societies, and changing environments.
The researchers suggest that understanding the complexity of treponemal disease history is essential for reconstructing how infectious diseases shaped human history. Especially as treponemal disease like yaws is re-emerging due to the climate crisis.
