In recent years, knowledge of the processes involved in the disappearance of the Neanderthals and the successful expansion of our species across Eurasia has substantially increased. Still, the spatiotemporal variability of the presumed mechanisms behind Neanderthals’ demise – climate change, fragile demography, inter-species competition – makes it very challenging to evaluate the replacement at a continental scale. The Iberian Peninsula, due to its cul-de-sac position and the role of its southern regions as one of the last refugia for the Neanderthals, represents an ideal natural setting for testing models of cultural and demographic trajectories leading to the final disappearance of those populations. FINISTERRA seeks to expand this framework by implementing an integrative, interdisciplinary, multi-scale approach to the archaeological and paleoenvironmental records associated with late Neanderthals in southwestern Iberia. Supported by an unprecedented combination of geoarchaeological, chronological, and paleoecological evidence, FINISTERRA will specifically (1) provide a detailed characterization of late Neanderthal adaptive systems, presenting highresolution data on the timeline of events leading to their final disappearance; (2) investigate the presence of the so-called early warning signals of Neanderthals’ collapse through the use of cutting-edge quantitative analyses of cultural and demographic trajectories; (3) explore alternative hypotheses of a gradual or sudden loss of Neanderthals’ resilience by considering the impacts of climate change and the spread of modern humans into western Eurasia. The results of this project will have crucial implications for our understanding of the factors contributing to the demise of our sister species, which ultimately were key components for our own success and uniqueness.