Multiple occurrences of the rare Uto-Aztecan premolar variant in Hungary point to ancient ties between populations of western Eurasia and the Americas

The Uto-Aztecan premolar (UAP) is a rare dental morphological variant long thought to be restricted to non-Arctic Native Americans. The recent discovery of four individuals with this trait in a Hungarian sample invites reassessment of its geographic distribution. Our goal is to assess the variation of this trait on a global level and provide an explanation for its distribution. Observations on over 300 medieval Hungarian dentitions, along with data from the C.G. Turner II database, provide the authors with a global perspective on the distribution of UAP. In addition to four instances of UAP from Hungary, additional European cases have been reported from Germany, Spain, Yugoslavia, and France. Although the trait is most common in non-Arctic Native Americans, it is absent in Africa, Arctic America, the Pacific, and Asia with a few isolated and problematic exceptions. Most papers on UAP have focused on the trait's presence in the Americas with some authors suggesting a possible New World mutation. Although rare outside of the Americas, four examples from Hungary, in addition to other reported cases from Europe, suggest a more complex history of the UAP. Recent paleogenomic research indicates that direct gene flow from a west Eurasian lineage to an Ancient Native American population may have taken place after their divergence from the ancestral Arctic Native American population (Ancient Paleo-Siberians), thus explaining its current distribution among Europeans and non-Arctic Native Americans.