Size variation in early human mandibles and molars from Klasies River, South Africa: Comparison with other middle and late Pleistocene assemblages and with modern humans

Authors

  • Danielle F. Royer,

    Corresponding author
    1. Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Stony Brook, NY 11794-4364
    • Department of Anthropology, Stony Brook University, SBS Building, Room S-501, Stony Brook, NY 11794-4363, USA
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  • Charles A. Lockwood,

    1. Department of Anthropology, University College London, London, WC1E 6BT, UK
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  • Jeremiah E. Scott,

    1. School of Human Evolution and Social Change, Institute of Human Origins, Arizona State University, Tempe, AZ 85287-4101
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  • Frederick E. Grine

    1. Department of Anthropology, Stony Brook University, Stony Brook, NY 11794-4364
    2. Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794-4364
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  • Sadly, Charlie Lockwood passed away prior to the completion of this manuscript. We are confident that he would have been satisfied with our final revisions, and we dedicate this paper to his memory.

Abstract

Previous studies of the Middle Stone Age human remains from Klasies River have concluded that they exhibited more sexual dimorphism than extant populations, but these claims have not been assessed statistically. We evaluate these claims by comparing size variation in the best-represented elements at the site, namely the mandibular corpora and M2s, to that in samples from three recent human populations using resampling methods. We also examine size variation in these same elements from seven additional middle and late Pleistocene sites: Skhūl, Dolní Věstonice, Sima de los Huesos, Arago, Krapina, Shanidar, and Vindija. Our results demonstrate that size variation in the Klasies assemblage was greater than in recent humans, consistent with arguments that the Klasies people were more dimorphic than living humans. Variation in the Skhūl, Dolní Věstonice, and Sima de los Huesos mandibular samples is also higher than in the recent human samples, indicating that the Klasies sample was not unusual among middle and late Pleistocene hominins. In contrast, the Neandertal samples (Krapina, Shanidar, and Vindija) do not evince relatively high mandibular and molar variation, which may indicate that the level of dimorphism in Neandertals was similar to that observed in extant humans. These results suggest that the reduced levels of dimorphism in Neandertals and living humans may have developed independently, though larger fossil samples are needed to test this hypothesis. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc.

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