Genomic validation of the differential preservation of population history in modern human cranial anatomy

Objectives: In modern humans, the significant correlation between neutral genetic loci and cranial anatomy suggests that the cranium preserves a population history signature. However, there is disagreement on whether certain parts of the cranium preserve this signature to a greater degree than other parts. It is also unclear how different quantitative measures of phenotype affect the association of genetic variation and anatomy. Here, we revisit these matters by testing the correlation of genetic distances and various phenotypic distances for ten modern human populations. Materials and Methods: Geometric morphometric shape data from the crania of adult individuals (n = 224) are used to calculate phenotypic PST, Procrustes, and Mahalanobis distances. We calculate their correlation to neutral genetic distances, FST, derived from single nucleotide polymorphisms (SNPs). We subset the cranial data into landmark configurations that include the neurocranium, the face, and the temporal bone in order to evaluate whether these cranial regions are differentially correlated to neutral genetic variation. Results: Our results show that PST, Mahalanobis, and Procrustes distances are correlated with FST distances to varying degrees. They indicate that overall cranial shape is significantly correlated with neutral genetic variation. Of the component parts examined, PST distances for both the temporal bone and the face have a stronger association with FST distances than the neurocranium. When controlling for population divergence time, only the whole cranium and the temporal bone have a statistically significant association with FST distances. Discussion: Our results confirm that the cranium, as a whole, and the temporal bone can be used to reconstruct modern human population history.