I’ve been intrigued by the murky history of syphilis for a few years now. The text above is from the start of an article I wrote for Science in 2008. At the time, scientists were split between two explanations for sudden appearance of syphilis at the end of the fifteenth century. According to one, it was caused by bacteria that had evolved in the New World and were brought back to Europe by Columbus’s crew. But other researchers found many skeletons with signs of syphilis in Europe, Africa, and Asia that appeared to have been from long before Columbus’s voyage. They argued that it must have started in the Old World, perhaps before people even left for the New