The fatal syphilis pathogen was infamously carried back to Europe from the Americas by the Italian explorer Christopher Columbus and his Spanish mercenaries in the late 15th century. That is how the tale goes.

The truth might not be as obvious as we think. Treponema pallidum or closely comparable strains may have been present in Europe even before Christopher Columbus returned from his first expedition in 1493, according to previous investigations of medieval bones and teeth.

A more nuanced picture of T. pallidum's prevalence in earlier centuries is emerging with newer data, however this is far from excusing Columbus for sowing a sickness that raced through Europe (or for the plagues Spanish armada carried to the Americas, killing dozens of Indigenous people).

That alternative hypothesis is strengthened by a recent study from a team of paleomicrobiologists, who discovered evidence of a T. pallidum infection in a thigh bone from the 7th or 8th century France. The researchers found antibodies unique to T. pallidum in the sick femur in addition to extracting fragmented DNA of a potential ancestor strain of T. pallidum.

According to a report that has been published, "these data break a century-old dogma in medical microbiology," written by French infectious disease expert Hamadou Oumarou Hama and colleagues.

The sick femur was discovered in 1987 during archaeological digs at Chapelle Saint-Vincent in Roquevaire, France, among a mass of other bones; nevertheless, its significance was not understood until much later.

Working in a lab that had never previously handled T. pallidum DNA, Hama and colleagues went to great measures to verify the pockmarked bone and the extracted samples weren't contaminated by DNA from other sources.

The diseased femur's extracted DNA and antibodies were both similar to a small section of the T. pallidum reference genome, but neither was discovered in a different unaffected bone from the same burial site that was used as a control.

If the data are correct, the researchers claim that T. pallidum infections first appeared in Europe eight hundred years ago.

"To the best of my knowledge," Aix-Marseille University microbiologist and co-author Michel Drancourt told journalist Maryn McKenna for Wired, "this is the first, proven, strong piece of evidence that the Treponema of syphilis were circulating in the European population before Columbus."

However, not everyone is persuaded. McKenna claims that there is no proof of syphilis outbreaks earlier than those that ravaged Europe in the 1490s.

In addition, distinct diseases are brought on by several subspecies of the spiral-shaped Treponema bacteria. Yaws is a specific disease caused by the T. pallidum pertenue subspecies, while bejel is a sickness caused by the T. pallidum endemicum subspecies. Both are skin illnesses, but unlike syphilis, neither can be spread through sexual contact.

Hama and colleagues may have found some evidence of a Treponema infection, but they cannot say with certainty that it was the source of syphilis; it may have been a subspecies that induced yawns, for instance.

Only 2.4 percent of the pallidum subspecies genome was covered by the damaged DNA from the 1,400-year-old bone, but it was almost identical to those regions, raising questions.

According to certain medical professionals, including Hama and colleagues, there is growing evidence that pertenue or endemicum was probably present in Europe when Columbus arrived, possibly brought from the Americas with a new, more contagious form called pallidum.

More information regarding the origins of syphilis may eventually become available, adding more specifics and completing the history of this still-stigmatized illness.