Hot debate: Identifying heat treatment in Australian archaeology using science and modern indigenous knowledge

Abstract The deliberate heat treatment of lithic material for stone tools is a critical and hotly debated subject in human evolution and archaeology, representing a major technological innovation. This engineering of material has proven hard to demonstrate with archaeological data, although experimental data back early records from southern Africa. There is scant evidence of heat treatment from records representing early modern human migrations out of Africa and along the migration routes through Sunda to Sahul. The long cultural sequences found in Australian archaeology, have rarely been assessed for heat treatment, although it was practised in recent times by Indigenous peoples. Using modern Indigenous knowledge and a comprehensive review of the latest heat treatment identification methods, we assess a Pleistocene to Holocene record spanning some 47,000 years, for signals of deliberate heat treatment. We find unambiguous evidence for heat treatment to occur only in the mid to late Holocene, corresponding to a time of significant change. We discuss these findings concerning stone tool technology as an adaptive response to changing environmental, economic and social contexts. Our unique approach offers global relevance to the study of deliberate heat treatment in prehistory and engages with global debates on technological organization theory.