TY - JOUR
T1 - The deep trabecular structure of first metacarpals in extant hominids
AU - Dunmore, Christopher J
AU - Bachmann, Sebastian
AU - Synek, Alexander
AU - Pahr, Dieter H
AU - Skinner, Matthew M
AU - Kivell, Tracy L
N1 - Funding Information:
The authors are grateful to Professor Mary Marzke for her decades of inspiring research into the evolution of the human hand. The authors also thank the following researchers or curators for access to specimens in their care: I. Livne (Powell‐Cotton Museum), A. vanHeteren and M. Hiermeier (Zoologische Staatssammlung München), C. Boesch and U. Schwarz (Max Planck Institute for Evolutionary Anthropology), A. Ragni (Smithsonian Institution, National Museum of Natural History); M. Teschler‐Nicola and R. Muehl (Natural History Museum, Vienna), J. Moggi‐Cecchi and S. Bortoluzzi (University of Florence), F. Mayer (Museum für Naturkunde—Leibniz Institute for Evolution and Biodiversity Science, Berlin), B. Großkopf (Johann‐Friedrich‐Blumenbach‐Institut für Zoologie und Anthropologie der Georg‐August‐Universität Göttingen), E. Gilissen and W. Wendelen (Musée Royal de l'Afrique Centrale), V. Volpato (Senckenberg Museum of Frankfurt). The authors thank the editors and three anonymous reviewers for their constructive comments that improved our manuscript. Dieter H. Pahr is CEO of Dr. Pahr Ingenieurs e.U., which develops and distributes Medtool. All other authors declare no competing interests. This research was supported by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant no. 819960).
Publisher Copyright:
© 2023 The Authors. American Journal of Biological Anthropology published by Wiley Periodicals LLC.
PY - 2023/2/7
Y1 - 2023/2/7
N2 - 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 differences in: (1) the absolute volume of trabecular volume fraction, (2) the distribution of the deeper trabecular network, and (3) the distribution of trabeculae in the medullary cavity, 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.
AB - 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 differences in: (1) the absolute volume of trabecular volume fraction, (2) the distribution of the deeper trabecular network, and (3) the distribution of trabeculae in the medullary cavity, 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.
UR - http://www.scopus.com/inward/record.url?scp=85147495327&partnerID=8YFLogxK
U2 - 10.1002/ajpa.24695
DO - 10.1002/ajpa.24695
M3 - Journal article
C2 - 36790736
SN - 2692-7691
JO - American journal of biological anthropology
JF - American journal of biological anthropology
ER -