title: Chewed out: an experimental link between food material properties and repetitive loading of the masticatory apparatus in mammals.
abstract: Using a model organism (rabbits) that resembles a number of mammalian herbivores in key aspects of its chewing behaviors, we examined how variation in dietary mechanical properties affects food breakdown during mastication. Such data have implications for understanding phenotypic variation in the mammalian feeding apparatus, particularly with respect to linking jaw form to diet-induced repetitive loading. Results indicate that chewing frequency (chews/s) is independent of food properties, whereas chewing investment (chews/g) and chewing duration(s), which are proportional to repetitive loading of the jaws, are positively related to food stiffness and toughness. In comparisons of displacement-limited and stress-limited fragmentation indices, which respectively characterize the intraoral breakdown of tough and stiff foods, increases in chewing investment and duration are linked solely to stiffness. This suggests that stiffer foods engender higher peak loads and increased cyclical loading. Our findings challenge conventional wisdom by demonstrating that toughness does not, by itself, underlie increases in cyclical loading and loading duration. Instead, tough foods may be associated with such jaw-loading patterns because they must be processed in greater volumes owing to their lower nutritive quality and for longer periods of time to increase oral exposure to salivary chemicals.
authors.affiliation: Departments of Biological Sciences, Aerospace and Mechanical Engineering, and Anthropology, University of Notre Dame , Notre Dame, IN , United States of America.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Ravosa
authors.affiliation: Department of Anthropology, Southern Illinois University , Carbondale, IL , United States of America.
authors.forename: Jeremiah E
authors.initials: JE
authors.lastname: Scott
authors.affiliation: Department of Biological Sciences, University of Notre Dame , Notre Dame, IN , United States of America.
authors.forename: Kevin R
authors.initials: KR
authors.lastname: McAbee
authors.affiliation: Department of Biological Sciences, University of Notre Dame , Notre Dame, IN , United States of America.
authors.forename: Anna J
authors.initials: AJ
authors.lastname: Veit
authors.affiliation: Department of Biological Sciences, University of Notre Dame , Notre Dame, IN , United States of America.
authors.forename: Annika L
authors.initials: AL
authors.lastname: Fling
keywords: Chewing parameters; Cyclical/repetitive loading; Diet; Food mechanical properties; Jaw loading patterns; Mammals; Mandibular morphology; Masticatory system; Rabbits