Molecules Versus Morphology? Not for the Human Cranium

Evolutionary investigations of human crania typically take a limited view of cranial diversity as they discount the possibility that human cranial variation could simply be due to the effects of random genetic drift, gene flow and mutation in favor of natural selection and developmental changes. Natural selection alone cannot explain similarities between patterns of cranial and molecular diversity observed in humans. It appears that the amount of phenotypic variance in the human cranium decreases at the population level as a function of distance from Sub-Saharan Africa much in the same way as observed for human molecular data.