title: Age-related variation in the mechanical properties of foods processed by Sapajus libidinosus.
abstract: OBJECTIVE
  The diet of tufted capuchins (Sapajus) is characterized by annual or seasonal incorporation of mechanically protected foods. Reliance on these foods raises questions about the dietary strategies of young individuals that lack strength and experience to access these resources. Previous research has demonstrated differences between the feeding competencies of adult and juvenile tufted capuchins. Here we test the hypothesis that, compared to adults, juveniles will process foods with lower toughness and elastic moduli.
  
  
  METHODS
  We present data on variation in the toughness and elastic modulus of food tissues processed by Sapajus libidinosus during the dry season at Fazenda Boa Vista, Brazil. Food mechanical property data were collected using a portable universal mechanical tester.
  
  
  RESULTS
  Results show that food tissues processed by the capuchins showed significant differences in toughness and stiffness. However, we found no relationship between an individual's age and mean or maximum food toughness or elastic modulus, indicating both juvenile and adult S. libidinosus are able to process foods of comparable properties.
  
  
  CONCLUSIONS
  Although it has been suggested that juveniles avoid mechanically protected foods, age-related differences in feeding competence are not solely due to variation in food toughness or stiffness. Other factors related to food type (e.g., learning complex behavioral sequences, achieving manual dexterity, obtaining physical strength to lift stone tools, or recognizing subtle cues about food state) combined with food mechanical properties better explain variation in juvenile feeding competency.
authors.affiliation: Center for Functional Anatomy and Evolution, Johns Hopkins University School of Medicine, Baltimore, MD.|Division of Basic Medical Sciences, Mercer University School of Medicine, Macon, GA.
authors.forename: Janine
authors.initials: J
authors.lastname: Chalk
authors.affiliation: Department of Anatomy, Kansas City University of Medicine and Biosciences, Kansas City, MO.
authors.forename: Barth W
authors.initials: BW
authors.lastname: Wright
authors.affiliation: Department of Bioclinical Sciences Faculty of Dentistry, Kuwait University, Safat, Kuwait.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Lucas
authors.affiliation: College of Veterinary Medicine, Cornell University, Ithaca, NY.
authors.forename: Katherine D
authors.initials: KD
authors.lastname: Schuhmacher
authors.affiliation: Department of Anthropology, Rutgers University, New Brunswick, NJ.
authors.forename: Erin R
authors.initials: ER
authors.lastname: Vogel
authors.affiliation: Department of Psychology, University of Georgia, Athens, GA.
authors.forename: Dorothy
authors.initials: D
authors.lastname: Fragaszy
authors.affiliation: Institute of Cognitive Sciences and Technologies, National Research Council, Rome, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Visalberghi
authors.affiliation: Department of Experimental Psychology, University of São Paulo, São Paulo, Brazil.
authors.forename: Patrícia
authors.initials: P
authors.lastname: Izar
authors.affiliation: Anthropology Division, American Museum of Natural History, New York, NY.
authors.forename: Brian G
authors.initials: BG
authors.lastname: Richmond
mesh_terms: D000367:Age Factors; D000818:Animals; D000885:Anthropology, Physical; D002428:Cebus / Q000502:physiology*; D055119:Elastic Modulus; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D005504:Food Analysis; D008297:Male; D010944:Plants / Q000737:chemistry
keywords: elastic modulus; juvenile primates; mechanically protected foods; toughness