1. Comparative Cultural Psychology Department, Max Planck Institute for Evolutionary Anthropology, D-04103 Leipzig, Germany
2. Empirical School and Classroom Research, Leipzig University, D-04109 Leipzig, Germany
3. Department of Engineering, Hochschule Nordhausen, University of Applied Science, D-99734 Nordhausen, Germany
4. Ecology of Animal Societies Department, Max Planck Institute of Animal Behavior, D-78467 Konstanz, Germany