1. Institute for Religion, Philosophy and History, University of Agder, Kristiansand, Gimlemoen, Kristiansand S, Norway
2. Department for Behavioural Ecology, University of Göttingen, Kellnerweg, Göttingen, Germany
3. Primate Social Evolution Group, German Primate Center Göttingen, Kellnerweg, Göttingen, Germany
4. Leibniz Science Campus Primate Cognition, Kellnerweg, Göttingen, Germany
5. School of Sociology and Anthropology, Sun Yat-sen University, Guangzhou, PR China
6. Ethologie Cognitive et Sociale, Centre National de la Recherche Scientifique, rue du loess, Strasbourg, France
7. Université de Strasbourg, CNRS, IPHC UMR, rue Becquerel Strasbourg Cedex, France