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Trabecular bone structure of the proximal capitate in extant hominids and fossil hominins with implications for midcarpal joint loading and the dart‐thrower's motion

Bird, Emma E., Kivell, Tracy L., Dunmore, Christopher J., Tocheri, Matthew W., Skinner, Matthew M. (2023) Trabecular bone structure of the proximal capitate in extant hominids and fossil hominins with implications for midcarpal joint loading and the dart‐thrower's motion. American Journal of Biological Anthropology, 183 (3). E-ISSN 2692-7691. (doi:10.1002/ajpa.24824) (KAR id:102227)

Abstract

Objectives: This research examines whether the distribution of trabecular bone in the proximal capitates of extant hominids, as well as several fossil hominin taxa, is associated with the oblique path of the midcarpal joint known as the dart‐thrower's motion (DTM).

Materials and Methods: We analyzed proximal capitates from extant (Pongo n = 12; Gorilla n = 11; Pan n = 10; fossil and recent Homo sapiens n = 29) and extinct (Australopithecus sediba n = 2; Homo naledi n = 1; Homo floresiensis n = 2; Neandertals n = 3) hominids using a new canonical holistic morphometric analysis, which quantifies and visualizes the distribution of trabecular bone using relative bone volume as a fraction of total volume (rBV/TV).

Results: Homo sapiens and Neandertals had a continuous band of high rBV/TV that extended across the scaphoid, lunate, and hamate subarticular regions, but other fossil hominins and extant great apes did not. A. sediba expressed a distinct combination of human‐like and Pan‐like rBV/TV distribution. Both H. floresiensis and H. naledi had high rBV/TV on the ulnar‐side of the capitate but low rBV/TV on the radial‐side.

Conclusion: The proximal capitates of H. sapiens and Neandertals share a distinctive distribution of trabecular bone that suggests that these two species of Homo regularly load(ed) their midcarpal joints along the full extent of the oblique path of the DTM. The observed pattern in A. sediba suggests that human‐like stress at the capito‐scaphoid articular surface was combined with Pan‐like wrist postures, whereas the patterns in H. floresiensis and H. naledi suggest their midcarpal joints were loaded differently from that of H. sapiens and Neandertals.

Item Type: Article
DOI/Identification number: 10.1002/ajpa.24824
Uncontrolled keywords: cancellous bone, fossil Homo, wrist, African apes, Australopithecus
Subjects: G Geography. Anthropology. Recreation
Divisions: Divisions > Division of Human and Social Sciences > School of Anthropology and Conservation
Funders: European Research Council (https://ror.org/0472cxd90)
Max Planck Society (https://ror.org/01hhn8329)
University of Kent (https://ror.org/00xkeyj56)
Calleva Foundation (https://ror.org/00jwxmn37)
SWORD Depositor: JISC Publications Router
Depositing User: JISC Publications Router
Date Deposited: 04 Aug 2023 10:43 UTC
Last Modified: 26 Feb 2024 12:54 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/102227 (The current URI for this page, for reference purposes)

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