Cranial adaptation to a high attrition diet in Japanese macaques

Susan Anton

    Research output: Contribution to journalArticle

    Abstract

    Primates with diets that require greater occlusal forces to process exhibit anteroposteriorly shorter, vertically deeper faces, more anteriorly placed masseter attachment areas, and broader, taller mandibular corpora compared to closely related species/populations. Japanese macaques (Macaca fuscata) eat different, perhaps mechanically tougher to process, foods than other macaques do. Accordingly, they should exhibit structural features of the skull related to dissipating great occlusal loads. To test this hypothesis I compared cranial variables amongst wild-caught, adult female skulls (n = 85) of M. fuscata and three other macaque species (M. mulatta, M. fascicularis, and M. nemestrina) and applied least-squares and reduced- major-axis regression analysis and principal components analysis (PCA) to 17 cranial variables reflecting facial, vault, and mandibular dimensions. When scaled for size, the Japanese macaque has a vertically deeper and anteroposteriorly shorter face, a broader but not taller mandibular corpus, and a more anteriorly placed masseter muscle than the other three macaques do. The first PCA axis isolates variation due to a suite of characters related to mechanical efficiency in dissipating occlusal loads (vertically deep face and broad corpus) and differentiates the Japanese macaques from the other species. This, coupled with reported dietary differences among species, suggests that Japanese macaques are selected for dissipating greater occlusal loads than other macaques are. The presence of a narrow mandible relative to cranial breadth and a hyperrobust mandibular corpus width suggests that axial torsion is a significant influence in the masticatory regime of M. fuscata. The lack of an increase in corpus height indicates that parasagittal bending is not as significant an influence. Geographic and climatic influences cannot account for the patterns of variation between M. fuscata and the other macaques.

    Original languageEnglish (US)
    Pages (from-to)401-427
    Number of pages27
    JournalInternational Journal of Primatology
    Volume17
    Issue number3
    StatePublished - Jun 1996

    Fingerprint

    Macaca fuscata
    diet
    Macaca
    skull
    principal component analysis
    torsion
    primate
    regression analysis
    muscle
    food
    mouthparts
    interspecific variation
    least squares
    Primates
    muscles

    Keywords

    • biomechanics
    • craniometrics
    • Macaca
    • mastication

    ASJC Scopus subject areas

    • Animal Science and Zoology

    Cite this

    Cranial adaptation to a high attrition diet in Japanese macaques. / Anton, Susan.

    In: International Journal of Primatology, Vol. 17, No. 3, 06.1996, p. 401-427.

    Research output: Contribution to journalArticle

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