Michael Winkelman, Ph.D. (University of California-Irvine), M.P.H. (University of Arizona) is an Associate Professor in the School of Human Evolution and Social Change at Arizona State University. He served as President of the Anthropology of Consciousness section of the American Anthropological Association, as was the founding President of its Anthropology of Religion Section. His principal publications on shamanism include Shamans, Priests and Witches (1992) and Shamanism (2000). He has also addressed the role of psychedelic medicines in shamanism in his co-edited Psychedelic Medicine. John Baker, Dr. Phil. (Universität Hamburg, Germany) is a Professor of Anthropology at Moorpark College. He has authored several papers on the constructive use of altered states of consciousness and on the history and ritual uses of psychoactive substances. He is presently serving as the President of the Society for the Anthropology of Consciousness.