Revealing the functions of Pleistocene EXpedient OSseous TECHnology with an innovative approach that integrates tribology with AI

Over the last two decades, growing evidence attests to the use of unmodified or partially modified bone fragments as tools by members of our lineage prior to the emergence of fully shaped, standardized bone tools. These simple tools, some of which date to 2.4 million years ago (Myr), were interpreted as items used for digging, piercing, cutting, or scraping but definitive conclusions are difficult to reach without comprehensive evidence owing to the lack of adequate research strategies for investigating them. Indeed, we critically need quantitative replicable methods to infer their role in past cultural systems, which, in turn, would allow us to document their evolution in relation to other aspects of Pleistocene material culture. ExOsTech aims to tackle this challenging task through the development and application of an innovative approach that integrates tribology with artificial intelligence to study use-wear patterns present on expedient osseous tools. This methodological breakthrough relies on discriminant analysis of surface textural data (ISO 25178) acquired by confocal microscopy as well as image recognitions and multi-class neural network algorithms to precisely establish the function of expedient osseous tools. This method will be applied to study assemblages from Europe, Southern Africa, and East Asia dated between 1.8 Ma and 60 thousand years ago (ka). Cross-cultural comparisons of regional trajectories will be performed to establish when expedient osseous tools became fully integrated in past cultural systems and when standardized behaviours guiding their selection and use emerged in our lineage. Ultimately, ExOsTech will offer a new perspective on Pleistocene cultural dynamics that can not otherwise be inferred solely from stone technology.