1. Centre for Social Learning and Cognitive Evolution, School of Biology, University of St. Andrews, Queen’s Terrace, St. Andrews, Fife KY16 9TS, UK.
2. Centre for the Coevolution of Biology and Culture, Department of Anthropology, University of Durham, Durham DH1 3LE, UK.
3. Michale E. Keeling Center for Comparative Medicine and Research, University of Texas M.D. Anderson Cancer Center, Bastrop, TX 78602, USA.
4. Département Ecologie, Physiologie et Ethologie, Institut Pluridisciplinaire Hubert Curien, Centre National de la Recherche Scientifique, Université de Strasbourg, F-67087 Strasbourg, France.