New research reveals that traces of Treponema pallidum—the bacteria responsible for syphilis—have been identified in the bones of ancient inhabitants of Colombia, dating back over 5,000 years. This discovery suggests that syphilis was infecting humans far earlier than previously believed, prior to the advent of intensive agriculture, which many experts think may have facilitated its spread.

Currently, Treponema pallidum encompasses three subspecies that cause syphilis, bejel, and framboise. The origins and transmission pathways of these diseases remain topics of scientific debate. Although ancient DNA and infectious markers on bones offer insights, they are often limited and ambiguous.

In a groundbreaking study, researchers analyzed DNA from 5,500-year-old remains discovered in the Bogotá savannah. The unexpected finding of Treponema pallidum in a human leg bone provides critical evidence of its historical prevalence.

“This discovery was entirely unanticipated, as there was a lack of skeletal evidence indicating an infectious disease,” notes Nasreen Broumandkoshbacht from the University of California, Santa Cruz.

Many scholars have long posited that the majority of diseases affected humans only after the rise of intensive agriculture, which led to denser populations. However, this individual lived in a contrasting setting—small, nomadic hunter-gatherer bands that maintained close contact with wild animals.

“These results shed light on the extensive evolutionary history of these organisms,” states Davide Bozzi from the University of Lausanne, Switzerland. “They reveal longstanding relationships between the bacterium and human populations.”

As researchers, including Blumandhoschbacht and Bozzi, correlated ancient genomes with contemporary ones, they identified that the pallidum strain was part of a distinct lineage, separate from any known modern relatives. This indicates that early variants of syphilis were already diversifying and infecting humans in the Americas millennia ago, with many of the same genetic traits that make present-day strains particularly pathogenic.

The findings imply that these pathogens were not only early residents in the Americas but may have been affecting human populations globally for much longer than previously assumed.

Rodrigo Barquera, a researcher at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, suggests that this ancient strain might link to an elusive “missing” pathogen, Treponema carathaeum, known primarily for its physical characteristics rather than its genetic makeup.

Kertu Majumdar, a researcher at the University of Zurich in Switzerland, posits, “The genomes of even older organisms might provide insights into a variety of extinct lineages and diseases caused by these pathogens.”

For Bozzi, unearthing the evolutionary adaptations of pathogens like syphilis is crucial for understanding their genetic attributes that enhance their virulence in new hosts.