1. Department of Comparative Language Science, University of Zürich, Zürich, Switzerland.
2. Center for the Interdisciplinary Study of Language Evolution, University of Zürich, Zürich, Switzerland.
3. Department of Psychology, University of York, York, UK.
4. Department of Anthropology, University of Zürich, Zürich, Switzerland.
5. School of Human Evolution and Social Change, and Institute of Human Origins, Arizona State University, Tempe, AZ, USA.
6. Departments of Anthropology and Biology, Tufts University, Medford, MA, USA.
7. Department of Anthropology, University of New Mexico, Albuquerque, NM, USA.
8. Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA.
9. Department of Psychology, University of Warwick, Warwick, UK.