Christopher Columbus is known for a lot of things, but turns out carrying syphilis to Europe after exploring the Americas and kick-starting a deadly epidemic isn’t one of them.
New DNA samples from nine skeletons suspected of having the infection in archaeological sites in Estonia, Finland and the Netherlands reveal traces of the bacteria that causes the sexually transmitted disease, according to a study published Aug. 13 in the journal Current Biology.
After analyzing the bacteria’s genetic information, the researchers found that syphilis might have been circulating in Europe decades before Columbus journeyed from the New World, and likely evolved between the 12th and 16th centuries (Columbus and his crew completed four voyages between 1492 and 1502).
“It seems that the first known syphilis breakout cannot be solely attributed to Columbus’ voyages to America,” study author Verena Schünemann, a professor of paleogenetics at the University of Zurich in Switzerland, said in a news release.
The idea, coined the “Columbian theory,” started because outbreaks of the disease in Europe coincided with the first American expeditions led by Columbus. So, in an attempt to bring more clarity to the theory, the researchers used dental drills to grind the bones into a fine powder and analyzed what was left of its DNA.
Four of the nine samples carried traces of syphilis, according to the study. Then, using a technique called molecular clock dating, the team was able to determine how old the bacterial genes were. They coupled this information with the skeletons’ and coffins’ ages to create a timeline.
In the process, the researchers found evidence of other related bacteria — one that causes yaws infection that affects the skin, bones and cartilage, which exists today in tropical regions, and another unknown one.
Although the timing suggests Columbus had nothing to do with the millions of deaths attributable to syphilis in the late 15th century, the study’s findings still aren’t conclusive.
The bones date back to a wide time scale, making some experts hesitant to declare Columbus innocent.
“It’s really interesting and really important that they’ve got these syphilis strains at around that time. What I’m less sure about is the exact time scale of the samples,” evolutionary epidemiologist Edward Holmes of the University of Sydney, who was not involved in the study, told Science.
Syphilis is a common disease that brings about sores in the genital or mouth area, but it can lead to serious complications, such as paralysis and dementia, if left untreated, according to the Centers for Disease Control and Prevention.
There were about 35,000 reported cases of syphilis in the U.S. in 2018, the highest number recorded since 1991, the agency said.