Molar enamel thickness in the Chacma Baboon, Papio ursinus (kerr 1792)

Bibliographic Data

ID8312403
AuthorsFrederick E Grine (0000-0002-5310-9005, Stony Brook University, corresponding author), Mark A Spencer (0000-0002-6209-3113, University of Colorado Denver), Brigitte Demes (Stony Brook University), Heather F Smith (0000-0002-3738-0903, Arizona State University), David Strait (0000-0002-3572-1663, York University), D S Strait, Deborah Constant (0000-0002-7176-9963, University of Cape Town), D A Constant
Year2005
Volume128
Issue4
Pages812-822
Publication date2005-12-01
Peer ReviewedYes
Open AccessYes
TypeARTICLE
VenueAmerican Journal of Physical Anthropology (JOURNAL)
Journal identifiersISSN: 0002-9483 • E-ISSN: 1096-8644
PublisherWiley (PUBLISHER • GB)
DOI10.1002/ajpa.20076
PMID16025532
OpenAlexW2054208426
LanguageEN
Citations received19
References cited56

Modern humans exhibit increasing relative enamel thickness from M1 to M3. Some biomechanical (basic lever) models predict that the more distal molars in humans encounter higher occlusal forces, and it has been postulated that this provides a functional explanation for the observed gradient in relative enamel thickness. However, constrained three‐dimensional models and experimental observations suggest that there is a reduction in bite force potential from M1 to M3, which would be consistent with the tendency for humans to reduce the size of the distal molars. In this regard, it has been postulated that the distal increase in enamel thickness is a consequence of crown size reduction; thus, it is unnecessary to invoke functional scenarios to explain this phenomenon. We assess these competing proposals by examining relative enamel thickness in a catarrhine primate ( Papio ursinus ) that exhibits crown size increase from M1 to M3. The molar row of P. ursinus is positioned relatively far forward of the temporomandibular joint, which results in the baboon being able to exert relatively greater muscle forces during posterior biting in comparison to modern humans. Thus, a significant distalward gradient of increasing enamel thickness would be expected in P. ursinus according to the hypothesis that posits it to be functionally related to bite force. The present study reveals no significant difference in relative enamel thickness along the molar row in P. ursinus . This finding lends support to the notion that the relatively thicker enamel of human distal molars is related primarily to their reduction in size. This carries potential implications for the interpretation of enamel thickness in phylogenetic reconstructions: the relatively thick molar enamel shared by modern humans and some of our fossil relatives may not be strictly homologous, in that it may result from different underlying developmental mechanisms. Am J Phys Anthropol, 2005. © 2005 Wiley‐Liss, Inc

Baboon · Biology · Bite force quotient · Biting · Cheek teeth · Crown (dentistry) · Enamel paint · Geometry · Molar · Primate · Reduction (mathematics) · Anatomy · Dentistry · Ecology · Evolution and Paleontology Studies · Mathematics · Medicine · Orthodontics · Paleontology · Pleistocene-Era Hominins and Archaeology · Primate Behavior and Ecology

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