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Terrestrial nest-building by wild chimpanzees (Pan troglodytes): Implications for the tree-to-ground sleep transition in early hominins

Authors

  • Kathelijne Koops,

    Corresponding author
    1. Department of Archaeology and Anthropology, Division of Biological Anthropology, University of Cambridge, Cambridge CB2 1QH, UK
    • Department of Archaeology and Anthropology, Division of Biological Anthropology, University of Cambridge, Cambridge CB2 1QH, UK
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  • William C. McGrew,

    1. Department of Archaeology and Anthropology, Division of Biological Anthropology, University of Cambridge, Cambridge CB2 1QH, UK
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  • Tetsuro Matsuzawa,

    1. Primate Research Institute, Kyoto University, Aichi 484-8506, Japan
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  • Leslie A. Knapp

    1. Department of Archaeology and Anthropology, Division of Biological Anthropology, Primate Immunogenetics and Molecular Ecology Research Group, University of Cambridge, Cambridge CB2 3QY, UK
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Abstract

Nest-building is a great ape universal and arboreal nesting in chimpanzees and bonobos suggests that the common ancestor of Pan and Homo also nested in trees. It has been proposed that arboreal nest-building remained the prevailing pattern until Homo erectus, a fully terrestrial biped, emerged. We investigated the unusual occurrence of ground-nesting in chimpanzees (Pan troglodytes), which may inform on factors influencing the tree-to-ground sleep transition in the hominin lineage. We used a novel genetic approach to examine ground-nesting in unhabituated chimpanzees at Seringbara in the Nimba Mountains, Guinea. Previous research showed that ground-nesting at Seringbara was not ecologically determined. Here, we tested a possible mate-guarding function of ground-nesting by analyzing DNA from shed hairs collected from ground nests and tree nests found in close proximity. We examined whether or not ground-nesting was a group-level behavioral pattern and whether or not it occurred in more than one community. We used multiple genetic markers to identify sex and to examine variation in mitochondrial DNA control region (HV1, HV2) sequences. Ground-nesting was a male-biased behavior and males constructed more elaborate (“night”) nests than simple (“day”) nests on the ground. The mate-guarding hypothesis was not supported, as ground and associated tree nests were built either by maternally-related males or possibly by the same individuals. Ground-nesting was widespread and likely habitual in two communities. We suggest that terrestrial nest-building may have already occurred in arboreally-adapted early hominins before the emergence of H. erectus. Am J Phys Anthropol 148:351–361, 2012. © 2012 Wiley Periodicals, Inc.

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