Dental morphology and ancient human dispersals within and out of Africa
We used traits from the Arizona State University Dental Anthropology System (ASUDAS) to investigate the Out-of-Africa II dispersal (∼70,000–50,000 BP) and biogeographic dynamics within the continent since the Late Pleistocene. Mean measure of divergence (MMD) distances from 32 recent global and five Early-Late Holocene African dental samples (n = 3167 individuals) were compared with FSTdistances from matched genetic samples (n = 566), serving as an independent line of validation. We then incorporated multidimensional scaling (MDS), Mantel correlations, linear regression, and novel minimum-slope geographic distances to reconstruct global population structure. Strong correlations (rm > 0.7) resulted between MMD and FST matrices and between the latter and their respective minimum-slope distances. The dental and genetic MDS plots revealed the patterning characteristic of seriated spatial or temporal data, indicating greater diversity within Africa than outside of it. Inclusion of the ancient samples revealed long-term phenetic continuity in East and South Africa and a south-north gradient in dental variation. Regressing MDS coordinates against minimum-slope distances yielded the highest R2 value for recent and ancient South African samples (≤0.86), mirroring genetic clines linked with deep Pleistocene structure and Holocene population movements. These findings are consistent with isolation by distance and compatible with serial founder processes associated with the Late Pleistocene dispersal from East Africa. They also suggest Sub-Saharan Africans had formed regionally structured but interconnected populations throughout the Holocene, with South African groups retaining high diversity and features reflecting deep ancestry. Overall, the ASUDAS traits broadly track population history and patterns observed in neutral genomic structure.
