Sundadonty Revisited: Dental Evidence Supports a Mixed East Asian and Australo‐Melanesian Ancestry for Southeast Asians
G. Richard Scott, Joel D. Irish, Arielle J. Pastore, Hannes Rathmann, Miguel E. DelgadoABSTRACT
Objectives
C.G. Turner divided the “Mongoloid” dental complex into Sinodonty and Sundadonty, but it remains unclear if the latter is a distinct complex or the product of Holocene gene flow between East Asians and the earlier inhabitants of Southeast Asia.
Materials and Methods
Dental data for 863 individuals representing 16 populations from East Asia, Southeast Asia, Australo‐Melanesia, and the Pacific were investigated. Three methods were employed: rASUDAS2 analysis based on a naïve Bayesian algorithm to classify individuals into clusters, the R‐matrix approach to obtain d ij distances, F ST , and r ij values among regional samples, and matrix correlation analysis to evaluate competing population history scenarios.
Results
The rASUDAS2 analysis revealed that Southeast Asians showed high variation and an indistinct dental complex, divided by East Asians (50.3%) and Australo‐Melanesians (49.7%). The d ij distances indicate that Southeast Asians share similarities with Australo‐Melanesians and East Asians, while the Pacific groups are closer to Australo‐Melanesians. The F ST obtained was 0.067, while the r ii values were: Southeast Asia = 0.027; Pacific = 0.057; Australo‐Melanesia = 0.076, and East Asia = 0.110. The matrix correlation analysis identified the migration scenario as the best‐supported model.
Discussion
Sundadonty does not represent a discrete or evolutionarily independent dental complex but rather results from admixture between Neolithic East Asian agriculturalists and Australo‐Melanesians. Southeast Asians are the most biologically heterogeneous populations investigated, coinciding with archaeological, linguistic and paleogenomic evidence showing multiple migrations and population events (admixture, replacement), which occurred during the past 5000 years. This supports a complex population history and diverse ancestral components in Southeast Asia.