Comments on the Zambian Kabwe Cranium (BH1) in the Context of Pleistocene Specimens of Homo and the Need for Species Definitions

This study is an extension of that which was undertaken by Balzeau et al. and published in this journal (2017), to reexamine the BH1 cranium which was initially described as Homo rhodesiensis in 1921, but more recently regarded as H. heidelbergensis. It is compared to other Pleistocene specimens of Homo. Balzeau et al. (2017) examined various cranial and intracranial characters, including the conformation of the mid-sagittal plane. They discussed the results of a geometric morphometrics analysis of the cranial vault's profile based on two Principal Components (PC1 and PC2). This note includes the third component (PC3). Taken together, the results can be assessed in the context of potential relationships in temporal and geographical dimensions. Recognizing that boundaries between species are not necessarily clear, we appeal for the adoption of a probabilistic definition of a paleontologi-cal species (sigma taxonomy, as opposed to conventional alpha taxonomy).