Dataset and BEAST2 XML Files for Phylogenetic Dating and Ancestral State Reconstruction of Austronesian and Kra-Dai Tattoos

As an iconic body culture of the Kra-Dai and Austronesian populations, tattoos can provide a crucial evolutionary cross-section of ethnic culture to corroborate interdisciplinary studies on population evolution—a cultural perspective that has long been absent from such research. However, utilizing tattoos for this purpose remains an unresolved challenge given the extreme paucity of ancient human skin remains and the lack of clear ethnic attribution for archaeological motifs. In this study, drawing on a comprehensive database of 1,404 high-confidence geometric tattoo records from 27 cultural areas spanning the 16th to the 21st centuries—which were scientifically refined into 77 traits—the evolutionary topology and ancestral states of Austro-Tai geometric tattoos were reconstructed using cultural phylogenetic methods, constrained by ancient DNA dating priors. Three core inferences emerged. First, the estimated median time of origin for the Austro-Tai common ancestor is 7,538 years before present. Subsequently, the stem nodes for the Austronesian and Kra-Dai branches were established at median times of 5,515 and 5,052 years before present, respectively. Second, ancestral geometric characteristics map to a basal background of basic zigzag waves and dotted sets, suggesting they are Pleistocene relicts. Third, a synchronous upsurge in figurative and linear motifs across the Taiwan Strait occurred around 2,500 years before present. While figurative motifs likely derived from a southward influx of northern cultures, the linear motifs suggest long-term, bidirectional cross-strait interactions. Crucially, this study demonstrates that Bayesian phylogenetics of cultural traits can independently elucidate key nodes of cultural origin and divergence. By contributing an independent cultural cross-section, it provides robust quantitative validation for the broader evolutionary history of the populations, complementing the facets previously reconstructed through linguistic, genetic, and archaeological research.