PÄR SEGERDAHL is Associate Professor of Philosophy at the Centre for Bioethics at the Karolinska Institute and Uppsala University in Sweden. He has published several philosophical inquiries into language in British and American journals, and in his book Language Use (1996). He currently leads a research project studying the concept of natural behaviour in domestic animals.WILLIAM FIELDS is Research Scientist at the new Great Ape Trust of Iowa in Des Moines (GATI), USA. Before the move to GATI he was Associate Program Director at the Language Research Centre in Atlanta, where he developed a novel anthropological understanding of ape language research. SUE SAVAGE-RUMBAUGH is Professor of Biology and Psychology at Georgia State University, USA. She has published results from her groundbreaking research on ape language in numerous scientific journals and in the influential books Apes, Language and the Human Mind (with Stuart G. Shaker and Talbot J.Taylor) and Kanzi: The Ape at the Brink of the Human Mind (with Roger Lewin). She is currently Director of the Bonobo Research Program at the Great Ape Trust of Iowa, USA.