Advanced dental reduction in Javanese Homo erectus

The postcanine tooth crowns of late Early Pleistocene Homo erectors from Sangiran, Java, have been considered to be significantly smaller than those of older H. erectus remains of the same region. In this study, the degree of dental reduction in the former was examined by comparing their postcanine crown size with that of various regional groups of recent H. sapiens. The results show that overall crown size and degree of posterior molar reduction of Javanese PI. erectus of the late Early Pleistocene was within the range of variation of recent H. sapiens. The position of this H. erectus group in the general trend of dental reduction in Early to Middle Pleistocene Asian archaic Homo is discussed. Implications for the phylogenetic discontinuity hypothesis between H. erectus and H. sapiens in Australasia are presented. In contrast to their reduced crown size, the Javanese H. erectus remains exhibit robust root systems, presumably a primitive retention. This observation indicates that reduction in crown size preceded reduction of the roots during evolution of Homo, at least in the Sunda region.