Those findings echo what University of Kansas paleoosteopathologist Bruce Rothschild concluded two decades ago. He said that his team has found that a diagnosis of treponemal disease in a single skeleton has, at best, a 70 percent chance of being correct.
And there remains no standard, reliable technique for making posthumous diagnoses of syphilis. At one New World site, for example, different studies have estimated the prevalence of anywhere from zero to 100 percent of skeletons affected by the disease.
Settling questions about how diseases have spread in the past could have future public health implications.
"One can look at syphilis, HIV, AIDS," and other diseases, Rothschild said. "If we understand how they spread, it gives us insight into how to manage diseases and bring them under control today."
Still, not all experts are convinced that syphilis began in the Americas.
Because the new study only looked at Old World skeletons and because accurate dating has yet to be done on many skeletons on both sides of the Atlantic, the question of where syphilis originated remains an open question, argued Charlotte Roberts, a biological archaeologist at the Durham University in the United Kingdom. Better dating and more rigorous diagnostics might eventually offer more clues.