rASUDAS2 A New Iteration of the Application for Assessing the Population Affinity of Individuals by Tooth Crown and Root Morphology

Abstract

The web-based application rASUDAS, originally based on data from “The Anthropology of Modern Human Teeth,” has been refined since its inception in 2015, undergoing two significant updates. The initial alpha version included 12 crown and five root traits. The beta version expanded the list to 15 crown traits and six root traits. The latest iteration, rASUDAS2, has expanded to include four additional traits along with seven backup traits, allowing for flexibility in cases where certain primary traits, like shoveling on UI1, cannot be scored, so shoveling expression on UI2 is utilized. The Bayesian algorithm powering rASUDAS2 employs trait frequencies derived from archaeological finds. To evaluate its effectiveness with contemporary samples, rASUDAS2 was tasked with calculating posterior probabilities for samples of African and European descent. Utilizing between 12 and 25 traits, it assigns individuals to one of seven major biogeographic groups: Western Eurasia (WE), East Asia (EA), American Arctic (AA), non-Arctic America (n-AA), Southeast Asia (SEA), Australo-Melanesia (AM), and Sub-Saharan Africa (SSA). In a modern African sample (n = 159), the probability of classification into the Sub-Saharan African group was the highest at 68.6%, followed by Western Eurasian at 22.0%, with probabilities ranging from 0.6% to 4.4% for the other groups. Similarly, in a European-derived sample (n = 161), 75.2% were assigned to Western Eurasia and 13.0% to Sub-Saharan Africa, with the remaining 12% distributed among other groups. Approximately three out of four individuals from these regions could be accurately placed within their respective biogeographic groups. However, the likelihood of these individuals being assigned to any Asian-related group is low, at less than 10%. When assessing two mixed African and European samples, results indicated nearly equal percentages of affinity assignment, with around 40% for Sub-Saharan African and 30% for Western Eurasian.