Stable nitrogen isotope analysis of dentine serial sections elucidate sex differences in weaning patterns of wild chimpanzees (Pan troglodytes)

Authors

  • Geraldine E. Fahy,

    Corresponding author
    1. Max Planck Institute for Evolutionary Anthropology, Department of Human Evolution, Leipzig, Germany
    2. Max Planck Institute for Evolutionary Anthropology, Department of Primatology, Leipzig, Germany
    • Correspondence to: Geraldine E. Fahy, Max Planck Institute for Evolutionary Anthropology, Department of Human Evolution, Deutscher Platz 6, 04107 Leipzig, Germany. E-mail: geraldine_fahy@eva.mpg.de

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  • Michael P. Richards,

    1. Max Planck Institute for Evolutionary Anthropology, Department of Human Evolution, Leipzig, Germany
    2. Department of Anthropology, University of British Columbia, British, Canada
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  • Benjamin T. Fuller,

    1. Max Planck Institute for Evolutionary Anthropology, Department of Human Evolution, Leipzig, Germany
    2. Laboratory of Biodiversity and Evolutionary Genomics, Centre for Archaeological Sciences, University of Leuven, Leuven, Belgium
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  • Tobias Deschner,

    1. Max Planck Institute for Evolutionary Anthropology, Department of Primatology, Leipzig, Germany
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  • Jean-Jacques Hublin,

    1. Max Planck Institute for Evolutionary Anthropology, Department of Human Evolution, Leipzig, Germany
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  • Christophe Boesch

    1. Max Planck Institute for Evolutionary Anthropology, Department of Primatology, Leipzig, Germany
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ABSTRACT

Offspring provisioning is one of the most energetically demanding aspects of reproduction for female mammals. Variation in lactation length and weaning strategies between chimpanzees (Pan troglodytes), our closest living relative, and modern human societies have been reported. When and why these changes occurred is frequently debated. Our study used stable nitrogen isotope data of tooth root dentine from wild Western chimpanzees (Pan troglodytes verus) in Taï National Park, Côte d'Ivoire, to quantify weaning in these chimpanzees and explore if infant sex plays a role in maternal investment. We analyzed serial sections of deciduous lateral incisor root dentine from four Taï chimpanzees to establish the δ15N signal of nursing infants; we then analyzed serial sections of first permanent mandibular molar root dentine from 12 Taï chimpanzees to provide quantitative δ15N data on weaning in this population. Up to 2 years of age both sexes exhibited dentine δ15N values ≈2–3‰ higher than adult female Taï chimpanzees, consistent with a nursing signal. Thereafter a steady decrease in δ15N values consistent with the onset, and progression, of weaning, was visible. Sex differences were also evident, where male δ15N values decreased at a significantly slower rate compared to females. Confirmation of sex differences in maternal investment among Taï chimpanzees, demonstrates the viability of using isotope analysis to investigate weaning in non-human primates. Additionally, assuming that behaviors observed in the Taï chimpanzees are illustrative of the ancestral pattern, our results provide a platform to enable the trajectory of weaning in human evolution to be further explored. Am J Phys Anthropol 153:635–642, 2014. © 2013 Wiley Periodicals, Inc.

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