[1] Univ Montpellier 2, Inst Evolutionary Sci, Montpellier, France
[2] Max Planck Inst Evolutionary Anthropol, Dept Primatol, Leipzig, Germany
[3] Duke Univ, Dept Biol, Durham, NC USA
[4] Duke Univ, Dept Biol Anthropol & Anat, Durham, NC USA
[5] Kyoto Univ, Primate Res Inst, Language & Intelligence Sect, Inuyama, Aichi 484, Japan