Treponematosis, which takes several forms, including syphilis, is a painful and disfiguring disease that appears in a variety of guises depending on climate and social customs. For historians interested in the origins or dissemination of disease, treponematosis presents a particular challenge because it bears a close resemblance to several other illnesses. Even paleopathologists attest to the difficulty of identifying the disease in skeletal remains, although they have studied treponematosis intensively for decades to determine whether it arose in Europe before or after the voyages of Columbus—a culturally fraught investigative framework now rejected by many.

Despite significant controversy, the debate among paleopathologists over the presence of treponematosis in premodern Europe and in western Asia has finally been settled in the affirmative by the discovery of enough evidence from skeletal remains to satisfy even the staunchest of skeptics. Yet it remains difficult to distinguish among the syndromes of the disease—bejel (Treponema pallidum endemicum), yaws (Treponema pallidum pertenue), and syphilis (Treponema pallidum pallidum)—that leave evidence in teeth and bones. (The fourth syndrome, pinta, or Treponema pallidum carateum, is a skin disease and therefore unrecoverable through paleopathology.) As the syndromes vary considerably in mortality rates and the level of human disgust they elicit, it is important to know which one is under discussion in any given case. Ancient DNA (aDNA) holds the answer, because just as only aDNA suffices to distinguish between treponematosis and other diseases that produce similar damage in the body, it alone can identify syndromes with absolute accuracy. Progress on uncovering the historical extent of syndromes remains slow, however, because the spirochete responsible for treponematosis, treponema pallidum, is rare in skeletal remains and fragile, making it notoriously difficult to recover and analyze. As a result, leaders in paleopathology have put out a call for more evidence of bejel, yaws, and syphilis from medieval documents and artworks to supplement their findings in teeth and bones. As observed by Brenda J. Baker and her co-authors, in their detailed and wide-ranging review of the literature published in 2020: