Introduction

An in-depth understanding of how our facial skeletal morphology arises during ontogeny is likely to lead to better understanding of the evolutionary, functional, and environmental influences that underpin variation. Thus, without an understanding of comparative postnatal growth we cannot hope to explain fully variation in the adult facial skeletons of modern and fossil hominins. Further, such understanding opens up new possibilities for practical applications such as the forensic classification by geographic subgroup of the faces of infants and juveniles as well as those of adults. In this chapter we will briefly review what is known of geographic variation and postnatal ontogeny in human crania before describing some of the results of our ongoing studies into interpopulation (geographic) differences and their ontogenetic basis. In so doing, we explore the possibility of classifying subadult material in the same way as is presently routinely carried out for adults.

Our recent studies have highlighted a great deal of variation within modern human ontogeny, as well as an early onset of morphologically distinct, population specific morphologies in modern humans (O'Higgins & Strand Viðarsdóttir, 1999; Strand Viðarsdóttir et al., 2002). These differences in ontogeny between modern human groups can sometimes be of equivalent scale to those documented between species of non-human primates (e.g., O'Higgins et al., 2001). This ontogenetic variability needs to be kept in mind when comparing the development of fossil hominin species to that of a single human population, or indeed a conglomerate sample of mixed populations, since such comparisons could lead to overgeneralized or, at worst, erroneous conclusions.