Dietary variation and food hardness in sooty mangabeys (Cercocebus atys): Implications for fallback foods and dental adaptation

Abstract

We present information on food hardness and monthly dietary changes in female sooty mangabeys (Cercocebus atys) in Tai Forest, Ivory Coast to reassess the hypothesis that thick molar enamel is parsimoniously interpreted as a response to consumption of hard foods during fallback periods. We demonstrate that the diet of sooty mangabeys varies seasonally, but that one food--Sacoglottis gabonensis--is the most frequently consumed food every month and year round. This food is the hardest item in the sooty diet. Given that this species has among the thickest enamel within the primate order, a plausible conclusion is that thick enamel in this taxon evolved not in response to seasonally critical function or fallback foods, but rather to the habitual, year round processing of a mechanically protected foodstuff. These data serve as a caution against de rigueur interpretations that reliance on fallback foods during lean periods primarily explains the evolution of thick enamel in primates.

Intra‐ and interspecific variation in macaque molar enamel thickness

“…Available data on macaque dietary intake and enamel thickness are not consistent with studies that suggest that thick enamel is an adaptation to protect teeth from fracture during feeding on hard objects as either a preferred or fallback food (Dumont, 1995;Lambert et al, 2004;Vogel et al, 2008;Constantino et al, 2009;Harrison and Marshall, 2011;McGraw et al, 2014). Macaca fuscata had the absolutely thickest enamel of our six species, but the wild population that is most ecologically similar to our sample did not consume a high proportion of foods generally characterized as "hard objects"; nuts, seeds, or pods (Agetsuma, 1995;Agetsuma and Nakagawa, 1998;Hanya, 2004;Tsuji et al, 2013).…”

“…Importantly, there are no year-round, quantitative feeding data available for M. mulatta or M. arctoides from undisturbed environments or unprovisioned populations. Here we employ a more robust sample in order to better explore enamel thickness variation within and among closely-related species, and to consider the extent to which these results are consistent with hypothesized explanations for enamel thickness variation, although definitive understanding awaits information on the mechanical properties of specific foods (e.g., Lambert et al, 2004;Vogel et al, 2008;McGraw et al, 2014). Gantt (1977) hypothesized that differences in enamel thickness among macaque species would reflect dietary variation or differences in body mass.…”

“…Information on the material properties of hominoid dietary items has also guided functional hypotheses (Lucas et al, 1994;Vogel et al, 2008;Constantino et al, 2009), Additional Supporting Information may be found in the online version of this article Grant sponsors: Harvard University, National Science Foundation; Grant number: BCS-0921978; Aichi Gakuin University, Wake Forest University, Primate Research Institute Kyoto University and the Nikon Corporation (Japan). Three main hypotheses have been proposed to explain primate enamel thickness variation: (1) thick enamel is advantageous for resisting fracture due to high bite forces generated during the mastication of hard foods (e.g., Kay, 1981;Dumont, 1995;Lambert et al, 2004;Vogel et al, 2008;Constantino et al, 2011;McGraw et al, 2012McGraw et al, , 2014; (2) thick enamel is advantageous for resisting abrasion caused by hard particles in or on food items (e.g., Jolly, 1970;Gantt, 1977;Rabenold and Pearson, 2011;Pampush et al, 2013); and/or (3) thin enamel is advantageous for shearing tough herbivorous food items (e.g., Kay, 1981;Ulhaas et al, 1999;Shimizu, 2002;Vogel et al, 2008). E-mail: tsmith@fas.harvard.edu although much less is known about the material properties of the diets of other primates.…”

Beyond the Map: Enamel Distribution Characterized from 3D Dental Topography

“…The higher the stress which enamel is supposed to withstand during the initial power stroke, the thicker the enamel is expected to be. This is consistent with the fact that most durophagous primates have a significantly thicker enamel compared with soft-food consumers of the same size (Molnar and Gantt, 1977; Kay, 1981; Martin, 1983, 1985; Dumont, 1995; Shellis et al, 1998; Lambert et al, 2004; Vogel et al, 2008; Constantino et al, 2011; Strait et al, 2013; McGraw et al, 2014; Smith et al, 2015; but see Pampush et al, 2013). …”

“…While challenging foods are generally avoided by primates (Milton, 1979; Waterman et al, 1988; Hill and Lucas, 1996; Lucas et al, 2000), some species such as Pithecia, Pongo , or Cercocebus are durophagous and are thus expected to show dental adaptations to stress-limited food, including a relatively thicker enamel than non-durophagous species (Vogel et al, 2008; Norconk and Veres, 2011; McGraw et al, 2014). Indeed, a thick enamel lessens the deformation due to strain (Lucas et al, 2008).…”