Dental ancestry estimation in a 1500 years old human skeleton from Slovenia using a new web-based application rASUDAS

Abstract

The present study was performed on a skeleton excavated from the Late Roman Period necropolis in Ptuj, Eastern Slovenia. Previous anthropological analysis has revealed that the skeleton belongs to a male, who died in his early twenties; however, determination of ancestry was problematic. The skull displays artificial cranial deformation of circular fronto-occipital type and shows some Asiatic anthroposcopic features. However, the inter-orbital projection method of Gill and Hughes has placed him into the Western Eurasian group. The aim of the present investigation was to estimate whether this individual belonged to Western Eurasian or Eastern Asian ancestry group by analyzing his dental morphology. Twenty-one key dental traits for ancestry assessment were scored following the Arizona State University Dental Anthropology System (ASUDAS). Morphology of the roots was scored from cone-beam computed tomography (CBCT) images of the dentition. These scores were input into a web application rASUDAS (beta version) which uses a naive Bayes classifier algorithm to assign an individual to a preselected number (from two to seven) of ancestry groups. The analysis revealed a complex tooth crown morphology (moderate maxillary incisor shoveling, 5-cusped maxillary first and second molars, 6-cusped mandibular first molars, 5-cusped mandibular second molars, multiple molar enamel extensions) and a simplified external root morphology (27 single-rooted teeth out of 32). Both mandibular second molars and the right mandibular third molar possess a C- shaped root canal. In addition, the mandible bilaterally exhibits accessory mental foramina. In a two-group analysis, the application calculated that the probability of assigning the individual from Ptuj to Eastern Asian ancestry group was close to 1.0. The result is in agreement with archaeological evidence which has indicated that this individual was a Hun warrior from the Migration Period of Europe. This study demonstrates a modern approach to estimating ancestry from dental morphology in bioarcheological and forensic contexts.