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Cortical bone architecture of hominid intermediate phalanges reveals functional signals of locomotion and manipulation

Syeda, Samar M., Tsegai, Zewdi J., Cazenave, Marine, Skinner, Matthew M., Kivell, Tracy L. (2024) Cortical bone architecture of hominid intermediate phalanges reveals functional signals of locomotion and manipulation. American Journal of Biological Anthropology, 184 (1). Article Number e24902. E-ISSN 2692-7691. (doi:10.1002/ajpa.24902) (KAR id:105109)


Objectives: Reconstruction of fossil hominin manual behaviors often relies on comparative analyses of extant hominid hands to understand the relationship between hand use and skeletal morphology. In this context, the intermediate phalanges remain understudied. Thus, here we investigate cortical bone morphology of the intermediate phalanges of extant hominids and compare it to the cortical structure of the proximal phalanges, to investigate the relationship between cortical bone structure and inferred loading during manual behaviors.

Materials and Methods: Using micro‐CT data, we analyze cortical bone structure of the intermediate phalangeal shaft of digits 2–5 in Pongo pygmaeus (n = 6 individuals), Gorilla gorilla (n = 22), Pan spp. (n = 23), and Homo sapiens (n = 23). The R package morphomap is used to study cortical bone distribution, cortical thickness and cross‐sectional properties within and across taxa.

Results: Non‐human great apes generally have thick cortical bone on the palmar shaft, with Pongo only having thick cortex on the peaks of the flexor sheath ridges, while African apes have thick cortex along the entire flexor sheath ridge and proximal to the trochlea. Humans are distinct in having thicker dorsal shaft cortex as well as thick cortex at the disto‐palmar region of the shaft.

Discussion: Variation in cortical bone distribution and properties of the intermediate phalanges is consistent with differences in locomotor and manipulative behaviors in extant great apes. Comparisons between the intermediate and proximal phalanges reveals similar patterns of cortical bone distribution within each taxon but with potentially greater load experienced by the proximal phalanges, even in knuckle‐walking African apes. This study provides a comparative context for the reconstruction of habitual hand use in fossil hominins and hominids.

Item Type: Article
DOI/Identification number: 10.1002/ajpa.24902
Uncontrolled keywords: cortical bone, functional morphology, phalangeal morphology, internal bone structure, hominin manual behaviors
Subjects: G Geography. Anthropology. Recreation
Divisions: Divisions > Division of Human and Social Sciences > School of Anthropology and Conservation
Funders: European Research Council (
SWORD Depositor: JISC Publications Router
Depositing User: JISC Publications Router
Date Deposited: 28 Feb 2024 14:47 UTC
Last Modified: 22 Apr 2024 11:28 UTC
Resource URI: (The current URI for this page, for reference purposes)

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