Interest in the pattern and rate of human colonization of Australia has been stimulated by the hypothesis that the arid interior of the continent was initially settled as late as 10,000-12,000 yr BP (ref. 1). The failure of several field projects to locate earlier sites, despite systematic searches, has lent support to this view. However, recent archaeological excavations at Puritjarra rockshelter, in Central Australia, have revealed a stratified deposit containing stone artefacts in levels dating to the late Pleistocene. Radiocarbon dates from this site indicate that the central part of the arid zone was settled by 22,000 yr BP, about 12,000 years earlier than previous studies2 have shown. These results provide first evidence of occupation of the central desert during the Pleistocene and should now end a decade of scientific speculation about the timing of human settlement in the arid zone1,3-5.