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The deep trabecular structure of first metacarpals in extant hominids

Dunmore, Christopher James, Bachman, Sebastian, Synek, Alexander, Pahr, Dieter H., Skinner, Matthew M., Kivell, Tracy L. (2023) The deep trabecular structure of first metacarpals in extant hominids. American Journal of Biological Anthropology, 183 (3). ISSN 2692-7691. (doi:10.1002/ajpa.24695) (KAR id:99955)

Abstract

Objectives: Recent studies have associated subarticular trabecular bone distribution in the extant hominid first metacarpal (Mc1) with observed thumb use, to infer fossil hominin thumb use. Here, we analyze the entire Mc1 to test for interspecific differencesin: (1) the absolute volume of trabecular volume fraction, (2) the distribution ofthe deeper trabecular network, and (3) the distribution of trabeculae in the medullarycavity, especially beneath the Mc1 disto-radial flange.

Materials and Methods: Trabecular bone was imaged using micro-computed tomography in a sample of Homo sapiens (n = 11), Pan paniscus (n = 10), Pan troglodytes(n = 11), Gorilla gorilla (n = 10) and Pongo sp., (n = 7). Using Canonical Holistic Morphometric Analysis (cHMA), we tested for interspecific differences in the trabecular bone volume fraction (BV/TV) and its relative distribution (rBV/TV) throughout the Mc1, including within the head, medullary cavity, and base.

Results: P. paniscus had the highest, and H. sapiens the lowest, BV/TV relative to other species. rBV/TV distribution statistically distinguished the radial concentrations and lack of medullary trabecular bone in the H. sapiens Mc1 from all other hominids. H. sapiens and, to a lesser extent, G. gorilla also had a significantly higher trabecular volume beneath the disto-radial flange relative to other hominids.

Discussion: These results are consistent with differences in observed thumb use in these species and may also reflect systemic differences in bone volume fraction. The trabecular bone extension into the medullary cavity and concentrations beneath the disto-radial flange may represent crucial biomechanical signals that will aid in the inference of fossil hominin thumb use.

Item Type: Article
DOI/Identification number: 10.1002/ajpa.24695
Uncontrolled keywords: cancellous bone, great apes, medullary cavity, pollex, thumb
Subjects: H Social Sciences
Divisions: Divisions > Division of Human and Social Sciences > School of Anthropology and Conservation
Funders: European Research Council (https://ror.org/0472cxd90)
Depositing User: Chris Dunmore
Date Deposited: 08 Feb 2023 15:56 UTC
Last Modified: 26 Feb 2024 12:41 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/99955 (The current URI for this page, for reference purposes)

University of Kent Author Information

Dunmore, Christopher James.

Creator's ORCID: https://orcid.org/0000-0002-8634-9777
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