New genetic evidence presented by US researchers on Monday supports the theory that Christopher Columbus introduced syphilis to Europe from the New World. This finding has reignited a long-standing debate about the origins of the disease. Through a genetic analysis of the syphilis family tree, researchers discovered that the closest relative of syphilis was a South American cousin that causes yaws, an infection caused by a sub-species of the same bacteria. Evolutionary biologist Kristin Harper from Emory University in Atlanta explained that while some believe syphilis is an ancient disease that dates back to our earliest human ancestors, their research suggests that it was brought from the New World to the Old World relatively recently in human history. Harper's study is published in the journal Public Library of Science Neglected Tropical Diseases. She stated that the research supports the "Columbian theory," which connects the first European syphilis outbreak in 1495 to the return of Columbus and his crew. Combining the genetic data with the epidemic in Naples in 1495 provides strong evidence for this theory. Syphilis, a sexually transmitted disease caused by the bacterium Treponema pallidum, begins as a sore and can progress to a rash, fever, and potentially lead to blindness, paralysis, and dementia. The origins of syphilis have been traced back to skeletal remains found in both the New World and the Old World, with chronic syphilis leaving distinct lesions on bones. Harper mentioned in a phone interview that it has a worm-eaten appearance. She utilized phylogenetics to examine the evolutionary relationships between 26 strains of Treponema, the bacteria family responsible for syphilis, bejel, and yaws. The study included two previously unsequenced strains of yaws from remote areas of Guyana. Harper sequenced 21 regions in search of DNA changes among the strains. They concluded that yaws is an ancient infection, while venereal syphilis is a more recent development. Harper believes a nonvenereal form of yaws evolved into venereal syphilis that could survive in the European climate, but the exact process is unclear. The origin of syphilis is believed to be from the New World, but its specific characteristics are unknown. In a commentary in the same journal, Connie Mulligan and colleagues from the University of Florida disagreed with Harper's analysis, stating that her conclusions were overly reliant on genetic changes from Guyana samples. Mulligan proposed that more accurate information could be obtained through DNA analysis of ancient bones or well-preserved tissues. Harper acknowledges that further research is necessary to fully understand how syphilis made its way to the New World. "This is like looking at a blurry picture," she remarked.