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 the Cairns Institute, James Cook University, Australia. She has published extensively on Amazonian languages, languages of New Guinea, linguistic typology, and language contact. Her other publications include Evidentiality (2004), and Imperatives and Commands (2010) (OUP).R. M. W. Dixon, PhD (1968) in Linguistics, University of London, Doctor of Letters (1991), The Australian National University, is Adjunct Professor at the Cairns Institute, James Cook University, Australia. He has published extensively on Australian Aboriginal languages, on Jarawara (from southern Amazonia), Fijian, the grammar and lexicography of English, linguistic typology and basic linguistic theory. His recent publications include volumes 1-3 of Basic Linguistic Theory (2010-2011) (OUP)