The relationship between size and expression of nonmetric traits on the human skull

Nonmetric traits are frequently analyzed in the field of anthropology to measure genetic relatedness, or biodistance, within or between populations. These studies are performed under the assumption that nonmetric traits are genetically inherited. However, much of the research on nonmetric traits has revealed that numerous factors can confound heritability. Skull size is one of the factors that are shown in some samples to have an effect on the expression of nonmetric traits. There is evidence that nonmetric trait expression is population specific; therefore, the current study was performed to determine if size-trait correlations would occur within a single population. Nonmetric traits in a sample of 20 skulls (South Eastern Asian origin) are analyzed to determine if there are correlations between skull size and expression of nonmetric traits. Intertrait correlations are also examined. This type of study is important because if the expression of certain nonmetric traits is related to factors outside of genetics, then those traits would not be useful in biodistance studies. The results of this study indicate that there are no correlations between overall skull size and nonmetric traits. However, correlations were found between individual measurements and nonmetric traits, as well as between traits.