Paleoneurology of Homo erectus: endocranial variation and proportions in african and asian samples

Abstract

There is still no agreement on the taxonomic and phylogenetic affinity between African, Chinese, and Indonesian specimens generally referred to as Homo erectus sensu lato. Apart from minor differences in brain size, no endocranial differences have consistently been described among these three groups. This study is aimed at evaluating differences in the endocranial proportions among these three geographical samples. We compute a multivariate survey on a set of traditional metric variables commonly used in paleoneurology, to evaluate the degree and pattern of endocranial variation in the whole group. Principal component analysis and cluster analysis have been computed on arcs and diameters, to quantify possible differences and shared patterns of variability. The three groups largely overlap in terms of morphological variation. The Indonesian sample displays a larger variation in terms of size, but more homogeneous proportions in terms of overall shape. However, group-specific differences cannot be tested statistically because of the small sample size. General morphometric affinity between specimens seems not influenced by geography. Independently upon the taxonomic and phylogenetic status of these three groups, the endocranial proportions cannot reveal patent differences in the overall brain form, at least taking into account the current available sample and the traditional endocranial diameters and curves. It remains to be evaluated whether or not discrete characters or shape analysis can reveal more localized or subtle differences between these three geographic groups.