1. Department of Sociobiology/Anthropology, University of Göttingen, Göttingen, Germany
2. Behavioral Ecology and Sociobiology Unit, German Primate Center, Göttingen, Germany
3. Psychology Department, University of Lethbridge, Lethbridge, Alberta, Canada
4. Applied Behavioural Ecology and Ecosystems Research Unit, UNISA, Johannesburg, South Africa
5. Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, USA
6. Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK