No brain expansion in Australopithecus boisei


  • John Hawks

    Corresponding author
    1. Department of Anthropology, University of Wisconsin-Madison, Madison, WI 53706-1393
    • Department of Anthropology, University of Wisconsin–Madison, 5240 Social Science Building, 1180 Observatory Drive, Madison, WI 53706–1393
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The endocranial volumes of robust australopithecine fossils appear to have increased in size over time. Most evidence with temporal resolution is concentrated in East African Australopithecus boisei. Including the KNM-WT 17000 cranium, this sample comprises 11 endocranial volume estimates ranging in date from 2.5 million to 1.4 million years ago. But the sample presents several difficulties to a test of trend, including substantial estimation error for some specimens and an unusually low variance. This study reevaluates the evidence, using randomization methods and a related test using an explicit model of variability. None of these tests applied to the A. boisei endocranial volume sample produces significant evidence for a trend in that species, whether or not the early KNM-WT 17000 specimen is included. Am J Phys Anthropol, 2011. © 2011 Wiley-Liss, Inc.