1 Ape Behaviour & Ecology Group, Department of Evolutionary Anthropology, University of Zurich, 8057 Zurich, Switzerland. Electronic address: kathelijne.koops@uzh.ch.
2 Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany.
3 School of Psychology and Neuroscience, University of St Andrews, St Andrews, KY16 9JP, UK.
4 Department of Anthropology, University of Victoria, Victoria, BC, Canada.
5 Technological Primates Research Group, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany.
6 Department of Anthropology, University of Miami, Coral Gables, Florida, 33146, USA.
7 Department of Anthropology, Washington University in St. Louis, St. Louis, Missouri, 63119, USA.
8 Primate Models for Behavioural Evolution Lab, Institute of Human Sciences, University of Oxford, UK.