Ontogeny of material stiffness heterogeneity in the macaque mandibular corpus


  • David J. Daegling,

    Corresponding author
    1. Department of Anthropology, 1112 Turlington Hall, University of Florida, Gainesville, FL
    • Correspondence to: David J. Daegling, Department of Anthropology, 1112 Turlington Hall, University of Florida, Gainesville, FL 32611, USA. E-mail: daegling@ufl.edu

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  • Michael C. Granatosky,

    1. Department of Evolutionary Anthropology, 201 Biological Sciences Building, PO Box 90383, Duke University, Durham, NC
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  • W. Scott McGraw

    1. Department of Anthropology, 4064 Smith Laboratory, 174 W. 18th Avenue, The Ohio State University, Columbus, OH
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Evidence is accumulating that bone material stiffness increases during ontogeny, and the role of elastic modulus in conditioning attributes of strength and toughness is therefore a focus of ongoing investigation. Developmental changes in structural properties of the primate mandible have been documented, but comparatively little is known about changes in material heterogeneity and their impact on biomechanical behavior.

We examine a cross-sectional sample of Macaca fascicularis (N = 14) to investigate a series of hypotheses that collectively evaluate whether the patterning of material stiffness (elastic modulus) heterogeneity in the mandible differs among juvenile, subadult and adult individuals. Because differences in age-related activity patterns are known to influence bone stiffness and strength, these data are potentially useful for understanding the relationship between feeding behavior on the one hand and material and structural properties of the mandible on the other.

Elastic modulus is shown to be spatially dependent regardless of age, with this dependence being explicable primarily by differences in alveolar versus basal cortical bone. Elastic modulus does not differ consistently between buccal and lingual cortical plates, despite likely differences in the biomechanical milieu of these regions. Since we found only weak support for the hypothesis that the spatial patterning of heterogeneity becomes more predictable with age, accumulated load history may not account for regional differences in bone material properties in mature individuals with respect to the mandibular corpus. Am J Phys Anthropol 153:297–304, 2014. © 2013 Wiley Periodicals, Inc.