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Abstract ObjectivesMaintaining effective and efficient occlusal morphology presents adaptive challenges for mammals, particularly because mastication produces interactions with foods and other materials that alters the geometry of occlusal surfaces through macrowear and/or catastrophic failure (i.e. “chipping”). Altered occlusal morphologies are often less effective for masticating materials of given diet—but not always—some species exhibit dental sculpting, meaning their dentitions are set up to harness macrowear to hone their occlusal surfaces into more effective morphologies (i.e. secondary morphologies). Here we show that dental sculpting is present in the folivorousPresbytis rubicundaof Borneo. MethodsThirty‐one undamaged lower second molars ofP.rubicundaexhibiting various stages of macroscopic wear were micro‐CT scanned and processed into digital surfaces. The surfaces were measured for convex Dirichlet normal energy (vDNE, a measure of surface sharpness), and degree of surface wear. Regression analyses compared surface sharpness with several measures of wear to test for the presence and magnitude of dental sculpting. ResultsPositive correlations between the wear proxies and vDNE reveal thatP.rubicundawear in such a way as to become sharper, and therefore more effective chewing surfaces by exposing enamel‐dentine junctions on their occlusal surfaces and then honing these junctions into sharpened edges. Compared to another primate folivore in which increasing surface sharpness with macrowear has been demonstrated (i.e.,Alouatta palliata), the worn surfaces are similarly sharp, but the dental sculpting process appears to be different. DiscussionThe results presented here suggest that not only do some primates exhibit dental sculpting and the attendant secondary morphology, but that there appear to be multiple different morphological configurations that can achieve this result.P.rubicundahas thicker enamel and a more stereotyped wear pattern thanA.palliata, although both show positive correlations of occlusal surface sharpness (vDNE) with various wear proxies. These findings shed light on the varied approaches for the maintenance of effective and efficient occlusal surfaces in primates.
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This content will become publicly available on March 11, 2026
Dental topographic analysis of a frugivorous great ape (Pan paniscus) wear series shows declining sharpness with wear
Dental topographic analysis is a suite of measurements designed to capture functional information about occlusal morphology that can be effectively applied to wear series. Recent studies have revealed that some primate folivores exhibit an apparent improvement in dental function (i.e., increased occlusal sharpness) with increased wear—a phenomenon termed ‘dental sculpting.’ While dental sculpting has been identified in a folivorous platyrrhine (Alouatta) and colobine (Presbytis), its prevalence across primate phylogeny and ecomorphology remains underexplored. A wear series of 13 bonobo (Pan paniscus) second mandibular molars were analyzed for dental topography and amount of wear. 3D surfaces were generated in Avizo from μCT data of specimens housed at the Royal Belgian Institute of Natural Sciences representing the broadest range of wear states available. Occlusal sharpness was measured as convex Dirichlet normal energy (DNE) using the R package molaR. Wear was quantified as the dentine exposure ratio (DER) by imaging specimens in occlusal view and measuring the ratio of exposed dentine area to total occlusal area. Linear regression analysis found that DNE declined significantly with increased DER (p= 0.002), with moderate explanatory power (r2= 0.555). These findings suggest that dental sculpting does not occur in Pan paniscus. Our results contrast with those found for the frugivorous platyrrhines Ateles and Plecturocebus, who maintain DNE with wear. Rather, they indicate that bonobos lack compensatory mechanisms to preserve occlusal sharpness across their lifespans and underscore the importance of nutrition gained through relatively soft dietary materials that do not require significant cutting or slicing to efficiently consume.
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- Award ID(s):
- 2018769
- PAR ID:
- 10652938
- Publisher / Repository:
- American Journal of Biological Anthropology
- Date Published:
- Format(s):
- Medium: X
- Location:
- American Journal of Biological Anthropology
- Sponsoring Org:
- National Science Foundation
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