Primate dietary ecology in the context of food mechanical properties

Abstract

Substantial variation exists in the mechanical properties of foods consumed by primate species. This variation is known to influence food selection and ingestion among non-human primates, yet no large-scale comparative study has examined the relationships between food mechanical properties and feeding strategies. Here, we present comparative data on the Young's modulus and fracture toughness of natural foods in the diets of 31 primate species. We use these data to examine the relationships between food mechanical properties and dietary quality, body mass, and feeding time. We also examine the relationship between food mechanical properties and categorical concepts of diet that are often used to infer food mechanical properties. We found that traditional dietary categories, such as folivory and frugivory, did not faithfully track food mechanical properties. Additionally, our estimate of dietary quality was not significantly correlated with either toughness or Young's modulus. We found a complex relationship among food mechanical properties, body mass, and feeding time, with a potential interaction between median toughness and body mass. The relationship between mean toughness and feeding time is straightforward: feeding time increases as toughness increases. However, when considering median toughness, the relationship with feeding time may depend upon body mass, such that smaller primates increase their feeding time in response to an increase in median dietary toughness, whereas larger primates may feed for shorter periods of time as toughness increases. Our results emphasize the need for additional studies quantifying the mechanical and chemical properties of primate diets so that they may be meaningfully compared to research on feeding behavior and jaw morphology.

Investigating the dental toolkit of primates based on food mechanical properties: Feeding action does matter

“…This partitioning is fundamental when it comes to the interpretation of physiology, morphology, or behavior. Yet, as proposed in the current study, dietary categories group together food items that have too wide a range of mechanical properties (Coiner‐Collier et al, ). Besides, the diet of primates can vary dramatically between localities (Butynski, ; Chiarello, ; Cuozzo & Sauther, ; Sauther & Cuozzo, ), between seasons (Brugiere, Gautier, Moungazi, & Gautier‐Hion, ; Chapman, ; MacKinnon & MacKinnon, ), from year to year (Chapman & Chapman, ; Harrison, Morrogh‐Bernard, & Chivers, ; Struhsaker, ), and even between sexes (Bowler & Bodmer, ; Cords, ; Doran‐Sheehy, Mongo, Lodwick, & Conklin‐Brittain, ).…”

Food mechanical properties and isotopic signatures in forest versus savannah dwelling eastern chimpanzees

“…However, in such studies, foods are still largely categorised in very broad terms (e.g., fruits, leaves, bark) that do not faithfully track their mechanical properties 12 . In addition, accessing foods often includes the removal of external tissues with the teeth to access the nutrients within.…”

Mandibular shape variation in mainland and insular hylobatids

“…Additionally, it is important to note that frugivory is a very broad dietary category. Differences in fruit material properties (such as fruit size or mechanical properties) and food acquisition processes (such as using the anterior dentition to remove a tough exocarp) can have significant biomechanical implications, making broad dietary categories such as frugivorous uninformative in a functional sense (Coiner‐Collier et al, 2016; Hoffman, 2009; Rowe, 1996). To date, differences in material properties and food acquisition strategies have not been assessed for H. lar and H. agilis .…”