1Department of Anthropology, University of Illinois at Urbana-Champaign, 2Department of Anthropology, Center for the Study of Human Origins, New York University, 3New York Consortium in Evolutionary Primatology, 4Office of the Chief Medical Examiner, New York City
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Body size reconstructions of fossil hominins allow us to infer many things about their evolution and lifestyle including diet, metabolic requirements, locomotion, and brain/body size relationships. Due to the importance of these implications, accurate reconstructions of body mass have been attempted on numerous fragmentary fossil hominin specimens. Most calculations require a known “calibration” sample usually composed of modern humans, other extant apes, or a combination of both. Caution must be taken in these analyses as estimates are sensitive to overall size and allometric shape differences between the fossil hominin and the reference sample.
Statistically, the presence of size and shape differences form testable hypotheses. In this research we test whether KNM-WT 15000 (Nariokotome Boy), a fairly complete Homo erectus skeleton, differs in size and shape from a large collection of modern humans. The modern human sample is comprised of recorded body mass and femoral measurements (head diameter, midshaft diameter) of 600 individuals from the Hamann-Todd Osteological Collection and the Pretoria Bone Collection. Results indicate that WT-15000 does not significantly differ from this collection of humans in size (Rx= 0.0065, p=0.9357) or shape (R=5.5478, p=0.0624) on the basis of femoral measurements. Body mass is estimated as 54.2kg using a classical calibration method and 56.5kg (95% PI: 34.1kg – 92.3kg) using inverse calibration. Because WT-15000 does not differ in size or shape, inverse calibration should provide an unbiased estimate.
These results indicate that a modern human sample is an appropriate reference sample for estimating body mass for WT-15000.
This research was funded in part by a research grant from the Department of Anthropology at the University of Illinois and Urbana-Champaign.