1. Institute of Human Origins, School of Human Evolution and Social Change, Arizona State University, Tempe, AZ 85287, USA.
2. Center for the Study of Human Origins, Department of Anthropology, New York University, New York, NY 10003, USA.
3. Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig 04103, Germany.
4. School of Anthropology and Conservation, University of Kent, Canterbury CT2 7NR, UK.