John Ryle, professor of Anthropology, Ecology at London University’s School of Oriental and African Studies, is the Africa Editor of the Times Literary Supplement and author of Warriors of the White Nile (1984), a popular ethnography of the Agar Dinka of South Sudan. He has worked as a social anthropologist in Sudan and Brazil and as a regional specialist in Africa for aid agencies and human rights organizations. He has been a research fellow at Nuffield College, Oxford (1996-97) and is a member of the Council of the Humanities Centre at the Central European University in Budapest. He is Chair of the Rift Valley Institute, an association of specialists in the countries of the Great African Rift Valley. With Bapiny Tim Chol, he directed ‘The Price of Survival’ (1994), a TV documentary about the civil war in Sudan. He is a contributor to the human rights handbook, Crimes of War (1999) and author of, or co-author, of numerous technical reports on relief and development. He writes frequently for newspapers and magazines in Britain and North America.