Populations of Homo erectus may have survived into the late Pleistocene of Java (<50,000 years ago), possibly coexisting with modern humans (H. sapiens) in both time and space. Such survival of H. erectus would parallel the coexistence of Neandertals and modern humans in Europe and also begs the question of why only modern humans remain in both regions today. This project tests whether such late-surviving populations of H. erectus existed in Indonesia through a two-year field program in the Solo River Valley, Java. The team will undertake new excavations, microstratigraphic work, and systematic faunal and taphonomic analyses of recovered remains at known sites in the 20 meter terrace (e.g. Jigar, Ngandong) and identify other sites in a similar geological context for test excavation. The team will also test the accuracy of the previously acquired radiometric age estimates (U-series/ESR ages) using other techniques (including radiocarbon (14C), closed system U-series, luminescence and cosmogenic radionuclide techniques). This is the first project to focus explicitly on questions of assemblage formation in Indonesia. These data, in conjunction with those developed for African and Eurasian localities, are critical pieces to modeling the evolution and dispersal of H. erectus. This project establishes a long term collaborative research and training program between Indonesian and American scholars dedicated to answering scientific questions and to the development of Indonesian scientific opportunities. The program is designed to include training opportunities for Indonesian and American students and infrastructure for Indonesian scientists and collections. Field and laboratory training opportunities and at least two PhD projects will be provided for Indonesian graduate students in addition to practical training in curation of systematic collections, taphonomic analyses, and geological field and excavation techniques. International field training will be provided for at least two American graduate students. The program is likewise designed to foster relationships between Indonesian and American graduate students with the goal of encouraging the creation of additional productive collaborations, such as the one between the PI and her Indonesian counterpart. The U.S. graduate students are female, the project thus provides field opportunities in areas (field geology and field paleoanthropology) in which women have been traditionally underrepresented. The project also supports laboratory training of at least one American undergraduate. Scientific research will be supported by augmenting the laboratory collections of Gadjah Mada University with additional computer equipment for field and lab archiving and by assisting in systematic curation efforts. Infrastructure, including curatorial equipment, are provided to ensure an appropriate environment for long term study.