The Relationships Among Jaw-Muscle Fiber Architecture, Jaw Morphology, and Feeding Behavior in Extant Apes and Modern Humans

Title

The Relationships Among Jaw-Muscle Fiber Architecture, Jaw Morphology, and Feeding Behavior in Extant Apes and Modern Humans

Creator

Taylor A B; Vinyard C J

Publisher

American Journal of Physical Anthropology

Date

2013
2013-05

Description

The jaw-closing muscles are responsible for generating many of the forces and movements associated with feeding. Muscle physiologic cross-sectional area (PCSA) and fiber length are two architectural parameters that heavily influence muscle function. While there have been numerous comparative studies of hominoid and hominin craniodental and mandibular morphology, little is known about hominoid jaw-muscle fiber architecture. We present novel data on masseter and temporalis internal muscle architecture for small-and large-bodied hominoids. Hominoid scaling patterns are evaluated and compared with representative New- (Cebus) and Old-World (Macaca) monkeys. Variation in hominoid jaw-muscle fiber architecture is related to both absolute size and allometry. PCSAs scale close to isometry relative to jaw length in anthropoids, but likely with positive allometry in hominoids. Thus, large-bodied apes may be capable of generating both absolutely and relatively greater muscle forces compared with smaller-bodied apes and monkeys. Compared with extant apes, modern humans exhibit a reduction in masseter PCSA relative to condyle-M-1 length but retain relatively long fibers, suggesting humans may have sacrificed relative masseter muscle force during chewing without appreciably altering muscle excursion/contraction velocity. Lastly, craniometric estimates of PCSAs underestimate hominoid masseter and temporalis PCSAs by more than 50% in gorillas, and overestimate masseter PCSA by as much as 30% in humans. These findings underscore the difficulty of accurately estimating jaw-muscle fiber architecture from craniometric measures and suggest models of fossil hominin and hominoid bite forces will be improved by incorporating architectural data in estimating jaw-muscle forces. Am J Phys Anthropol 151:120-134, 2013. (C) 2013 Wiley Periodicals, Inc.

Subject

african apes; anthropoid primates; Anthropology; consequences; cross-sectional area; diet; evolution; Evolutionary Biology; finite-element-analysis; functional; hominoids; internal architecture; macaca-fascicularis; mandibular symphysis; masseter; mountain gorilla; pan-troglodytes; Temporalis

Identifier

Format

Journal Article

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Rights

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

Pages

120-134

Issue

1

Volume

151

Citation

Taylor A B; Vinyard C J, “The Relationships Among Jaw-Muscle Fiber Architecture, Jaw Morphology, and Feeding Behavior in Extant Apes and Modern Humans,” NEOMED Bibliography Database, accessed September 24, 2021, https://neomed.omeka.net/items/show/7302.

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