STEVE WEBB is Professor of Australian Studies at Bond University, in Queensland, Australia. He has previously carried out a pioneering palaeopathological study of Aboriginal health patterns prior to European colonisation, and has previously published Paleopathology of Aboriginal Australians (1995; ISBN 0521 460441). His research now concentrates on Australian regional human evolution, reasons for the extinction of Australia's megafauna, Upper Pleistocene migration and the earliest human settlement of the continent. His particular focus is on palaeoenvironmental change accompanying the last two...