The main purpose of Christopher Columbus' famed 1492 voyage was to open trade routes to bring back treasure and spices to Europe. But new evidence has emerged suggesting that Columbus may also have brought back some unintended cargo: syphilis.

Since the first recorded epidemic of venereal syphilis occurred in Europe in 1495, just three years after Columbus returned from his discovery of the New World, scientists have long suspected that the voyage was the source of the disease. A few kinks in the evidence kept the theory from becoming mainstream, however. For instance, there existed skeletal remains from both the Old and New World that allegedly showed signs of syphilis infection before Columbus' voyage.

A new analysis of that skeletal evidence by Emory University researchers, however, may have finally closed the case, according to

"This is the first time that all ... of these cases have been evaluated systematically," said George Armelagos, co-author of the study. "The evidence keeps accumulating that a progenitor of syphilis came from the New World with Columbus' crew and rapidly evolved into the venereal disease that remains with us today."

According to Armelagos and his colleagues, none of the skeletal evidence opposing the idea of a Columbian origin for syphilis held up to scrutiny. Most of the remains failed to meet at least one of the standardized, diagnostic criteria for chronic syphilis: the pitting on the skull and long bones known as caries sicca.

For the few cases that did meet this criteria, there were serious questions about how they were dated. For instance, all of these cases came from coastal regions where seafood was common in the diet. This kind of environment can throw off radiocarbon dates because of the so-called "marine reservoir effect," whereby seafood can become contaminated by older carbon brought to the surface by upwelling in ocean currents. After this effect was accounted for in the radiocarbon analysis, all of the skeletal remains fit a timeline consistent with the Columbian origin theory.

"Once we adjusted for the marine signature, all of the skeletons that showed definite signs of [the] disease appeared to be dated to after Columbus returned to Europe," said researcher Kristin Harper, one of the study's contributors.

Though it may be difficult to believe that such a small group of sailors — possibly even Columbus himself — could become the source for one of Europe's most devastating epidemics, it just goes to show how vulnerable human populations can become when a new pathogen is introduced.

"Syphilis has been around for 500 years," added Molly Zuckerman, another study contributor. "People started debating where it came from shortly afterwards, and they haven't stopped since. It was one of the first global diseases, and understanding where it came from and how it spread may help us combat diseases today."

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