Advanced dental reduction in Javanese Homo erectus

Abstract

The postcanine tooth crowns of late Early Pleistocene Homo erectus 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 H. 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.

Possible causes and significance of cranial robusticity among Pleistocene–Early Holocene Australians

“…However, previous studies of dental traits have noted that modern Australians and Melanesians are phenetically close to subSaharan Africans, consistent with the idea of a symplesiomorphic relationship between them (Irish, 1998;Irish and Guatelli-Steinberg, 2003). Moreover, recent studies by Kaifu (2006) have shown that Australians are indistinguishable from early anatomically modern Africans in terms of tooth size (a situation confirmed by unpublished analyses of the present author). Moreover, an apparent trend in dental crown size reduction in H. erectus in Java meant that molar crowns were overlapping the modern human size range by around 1.0 Ma (Kaifu, 2006).…”

“…Moreover, recent studies by Kaifu (2006) have shown that Australians are indistinguishable from early anatomically modern Africans in terms of tooth size (a situation confirmed by unpublished analyses of the present author). Moreover, an apparent trend in dental crown size reduction in H. erectus in Java meant that molar crowns were overlapping the modern human size range by around 1.0 Ma (Kaifu, 2006).…”

Descriptions of the dental remains of <i>Homo floresiensis</i>

“…During the course of the Homo evolution, the posterior molars experienced more marked size reduction than in the first molar, resulted in alteration of the molar size sequence within a dentition, from plesiomorphic 'M1 < M2 ≥ M3' to 'M1 > M2 > M3' (Wolpoff, 1971;Bermúdez de Castro and Nicolás, 1995;Kaifu et al, 2005b;Kaifu, 2006). The maxillary and mandibular molar size in H. floresiensis decreases posteriorly (M1 ≥ M2 > M3).…”

Early Pleistocene Homo erectus fossils from Konso, southern Ethiopia

“…Antón, 2003;Kaifu et al, 2005b;Dennell and Roebroeks, 2005;Durband et al, 2005;Kaifu, 2006;Rightmire, 2006). The purpose of this paper is to provide a fuller description of the Konso H. erectus fossils in comparison with previously known African materials, and to evaluate the eastern African H. erectus lineage with the additional perspective that the Konso assemblage provides.…”