New genetic evidence presented by US researchers suggests that Christopher Columbus may have introduced syphilis to Europe from the New World, sparking a debate on the disease's origins. Through a genetic analysis of the syphilis family tree, researchers found that its closest relative is a South American cousin that causes yaws. Evolutionary biologist Kristin Harper from Emory University in Atlanta believes that syphilis or a precursor of the disease came from the New World to the Old World relatively recently in human history. The study was published in the journal Public Library of Science Neglected Tropical Diseases. She stated that the research gives credibility to the "Columbian theory," which connects the first recorded European syphilis outbreak in 1495 to Columbus and his crew returning. "When you combine our genetic findings with that outbreak in Naples in 1495, it strongly supports the Columbian hypothesis," she explained. Syphilis, a sexually transmitted disease caused by the Treponema pallidum bacterium, starts as a sore and can progress to a rash, fever, and eventually lead to blindness, paralysis, and dementia. The most recent evidence of its origins comes from skeletal remains discovered in both the New World and the Old World. Chronic syphilis can leave distinctive lesions on bones. During a telephone interview, Harper described it as having a worm-eaten appearance. She utilized phylogenetics to analyze the evolutionary relationships among 26 strains of Treponema bacteria, which cause syphilis, bejel, and yaws. The study included sequencing two previously unexamined strains of yaws from remote areas in Guyana. Harper examined 21 different regions in search of DNA changes among the strains. They came to the conclusion that while yaws has been around for a long time, venereal syphilis is a more recent infection. Harper believes that a nonvenereal form of yaws in the tropics evolved into venereal syphilis that could survive in the colder European climate. However, it is unclear how this transformation occurred. Harper stated that the precursor of syphilis originated in the New World, but its exact nature remains unknown. In a commentary in the same journal, Connie Mulligan and colleagues from the University of Florida disagreed with Harper's analysis, suggesting that her conclusions relied too heavily on genetic changes from the Guyana samples. Mulligan proposed that more accurate information could be obtained by analyzing DNA extracted from ancient bones or preserved tissues. Harper agrees that further research is necessary to clarify the transmission of syphilis to the New World. "This is a low-quality image," she remarked.