After the French King Charles VIII invaded Italy in 1494, an unknown and disfiguring disease broke out in the army camps, spreading suddenly across Europe as the men returned to their homelands the following year.
The epidemic is considered the first historical report of syphilis, but where the disease came from has been debated by scientists ever since. One camp is believed to have originated in the Americas and was brought to Europe by Columbus in 1493. Another suggests that it was lurking in Europe before the explorer set sail.
Now ancient DNA recovered from skeletons across America has shed light on the mystery. The disease-ravaged bones, created before Columbus’ first voyage to the New World, contained genomes of bacteria from the syphilis family of diseases, suggesting the infection originated in the Americas.
Syphilis belongs to a small family of diseases that also includes syphilis and bejel. While syphilis is common throughout the world, yaws and bejel are neglected tropical diseases that occur primarily in equatorial regions. All three conditions are caused by strains of Treponema pallidum Bacteria.
“We were able to reconstruct five genomes from these bones and see that they are sister lineages to modern strains of the bacterium that circulates in humans today,” said Dr. Kirsten Bos, group leader for molecular paleopathology at the Max Planck Institute for Evolutionary Anthropology in Leipzig. “They all seem to have appeared in the Americas.”
In Nature, Bos and her colleagues describe how they extracted and reconstructed ancient objects T Pallidum DNA from the skeletal remains, including a hip bone from Argentina, a lower leg bone from Chile, upper and lower leg bones from Mexico and a tooth from Peru.
Because the researchers knew the age of the bones from radiocarbon dating, they were able to trace the different bacterial strains back to a common ancestor that lived no more than 9,000 years ago.
“This is a time when humans were already well established in the Americas and were not yet interacting with populations in other parts of the world. They were basically geographically and biologically isolated in the Americas,” Bos said.
The finding suggests that syphilis and its known relatives originated in the Americas but spread worldwide through human trafficking and European spread to the Americas and Africa in the decades and centuries following the early epidemic.
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However, it is unlikely that a line will be drawn under the debate.
“I don’t think we necessarily solve the puzzle because there are still so many important questions we need to answer,” Bos said. “We look at very limited data sources and try to analyze them holistically and comprehensively and be very open-minded. I think the narrative will continue to be discussed.”
