Alexandra Y. Aikhenvald, Ph.D. (1984) in Linguistics, Academy of Science of the USSR, Doctor of Letters (2006), La Trobe University, Australia, is Professor and Research Leader (People and societies of the tropics) at Cairns Institute, James Cook University, Australia. She has published extensively on Amazonian languages, languages of New Guinea , linguistic typology, and language contact. Her major publications include Evidentiality (2004),and Imperatives and Commands (2010) (OUP). Pieter C. Muysken, Ph.D. (1977) in Linguistics, University of Amsterdam, is Professor of Linguistics at Radboud University Nijmegen. He has published widely in the field of Andean languages, language contact, creoles and general linguistics, and is the author of Bilingual Speech: A Typology of Code-mixing (2000) and Functional Categories (2008).