Morphometric analysis of modern human crania: a framework for assessing early Pleistocene homonids

Abstract

Craniofacial measurements have been obtained from modern human skulls from cadavers representing several southern African population groups including Ndebele, Shangaan, Sotho, Swazi, Tswana, Xhosa and Zulu, in addition to European Homo sapiens. The measurements were obtained from crania in the Dart Collection housed at the School of Anatomical Sciences of the University of the Witwatersrand. Pairwise comparisons, using least squares linear regression analysis of cranial measurements, were used to calculate the standard error of them-coefficient associated with the general equation y = mx + c, where m is the slope of the regression line. The standard error of the m-coefficient is a measure of the degree of similarity between specimens. Log transformed s.e.m values (log s.e.m) show a normal distribution with a mean value of –1.84 ± 0.087 (n = 384 pairwise comparisons). These results can be used as a frame of reference for comparing Early Pleistocene specimens. For example, a comparison between KNM-ER 1813 (attributed to H. habilis) and KNM-ER 3733 (attributed to H. erectus or H. ergaster) is associated with a log s.e.m value of –1.844. Despite differences in size, these two penecontemporary hominid fossils are associated with a high probability of conspecificity, since the log s.e.m value is identical to the mean log s.e.m value of –1.84 obtained for pairwise comparisons of modern Homo sapiens.