New genetic evidence supports the view that Columbus introduced syphilis to Europe. The first recorded syphilis epidemic happened in 1495, fueling centuries of debate as to whether the germ came from the Americas or existed previously in the Old World but had not been distinguished from other skin-lesion diseases until 1500. To uncover syphilis's origins, scientists at Emory University and their colleagues genetically compared strains of the microbe from around the world with related bacteria. They found that syphilis's closest kin were South American variants of yaws, a disease spread by skin contact and limited to hot and humid areas. One theory suggests that syphilis became sexually transmitted only after it reached Europe, where more clothing and cooler climes limited the ways it could otherwise spread. Ultimately the progenitors of syphilis may be as old as humanity, hitching a ride with migrants to the Americas millennia before Columbus, speculate researchers in the January 15 PLoS Neglected Tropical Diseases.