The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)


The mechanical properties of maximum ingested bite size

ADAM HARTSTONE-ROSE1, TAYLOR J. CRISTE1, KRISTEN E. MACNEILL1, NATHAN A. YASIKA1, LUCAS J. PASSMORE1 and JONATHAN M.G. PERRY2.

1Biology, Pennsylvania State University, Altoona, 2Anatomy, Midwestern University

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Previously we found that Maximum Ingested Bite Size (Vb) – the largest piece of food that an animal will ingest whole without biting first – scales isometrically with body size for three foods and seventeen species of strepsirrhines at the Duke Lemur Center (DLC). Frugivores consistently ate larger pieces of food than did folivores. Furthermore, all species ate larger pieces of melon than the more obdurate carrot and sweet potato. If Vb can be expressed in terms of food mechanical properties then it will be possible to compare data across food types, including wild lemur foods, to better understand dietary adaptations in lemurs. To this end we quantified Vb in five species of lemurs at the DLC using ten types of food that vary widely in elasticity and toughness to determine how these properties relate to bite sizes. We found that, across all species (and for two individual species) Vb correlates significantly with food elasticity (r-square=0.49, F-Prob.<0.035); all species eat larger pieces of highly elastic (e.g., melon and pear) than less elastic (e.g., carrot) foods. There is no significant relationship between Vb and toughness in the whole sample or in any species. This suggests that elasticity may be driving bite size variation among foods and that this mechanical property should be the focus of food studies in the wild. Furthermore, these data suggest that lemurs may be judging the degree to which food can be deformed to fit into the oral cavity as they ingest pieces.

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