Comparing frontal cranial profiles in archaic and modern Homo by morphometric analysis

Archaic and modern human frontal bones are known to be quite distinct exter nally, by both conventional visual and metric evaluation, Internally this a rea of the skull has been considerably less well-studied, Here we present r esults from a comparison of interior, as well as exterior, frontal bone pro files from CT scans of five mid-Pleistocene and Neanderthal crania and 16 m odern humans, Analysis was by a new morphometric method, Procrustes analysi s of semi-landmarks, that permits the statistical comparison of curves betw een landmarks. As expected, we found substantial external differences betwe en archaic and modern samples, differences that are mainly confined to the region around the brow ridge, However, in the inner median-sagittal profile , the shape remained remarkably stable over all 21 specimens. This implies that no significant alteration in this region has taken place over a period of a half-million years or more of evolution, even as considerable externa l change occurred within the hominid clade spanning several species. This c onfirms that the forms of the inner and outer aspects of the human frontal bone are determined by entirely independent factors, and further indicates unexpected stability in anterior brain morphology over the period during wh ich modern human cognitive capacities emerged, Anat Rec (New Anat): 257:217 -224, 1999. (C) 1999 Wiley-Liss, Inc.