Bernd Heine is Emeritus Professor of Linguistics at the Institute of African Studies, University of Cologne. His 33 books include Possession: Cognitive sources, forces, and grammaticalization (CUP, 1997); Auxiliaries: Cognitive Forces and Grammaticalization (OUP, 1993); Cognitive Foundations of Grammar (USA, 1997); with Derek Nurse, African Languages: An Introduction (CUP, 2000), A Linguistic Geography of Africa (CUP, to appear 2007). Tania Kuteva is Professor of English Linguistics at the University of Düsseldorf and author of Auxiliation: An Enquiry into the Nature of Grammaticalization (OUP, 2001). Bernd Heine and Tania Kuteva are the joint authors of World Lexicon of Grammaticalization (CUP, 2002) and Language Contact and Grammatical Change (CUP, 2005), and The Changing Languages of Europe (OUP, 2006).