Characterization of new obsidian sources, artifact provenance, and inferred patterns of mobility and social dynamics in the Ethiopian Middle Stone Age.

Geochemical provenance of obsidian artifacts provides critical insights into prehistoric mobility, resource exploitation strategies, and group interactions. Despite Ethiopia's abundant obsidian outcrops and extensive archaeological record, the scope of provenance studies has been limited by several yet unidentified geological sources. This study integrates newly discovered geological obsidian sources from the Afar Rift with the characterization of >100 Middle Stone Age (MSA) artifacts-the largest single study of its kind-to reconstruct the patterns of raw material procurement, mobility, and social networks. It also incorporates data on dozens of previously characterized MSA obsidian artifacts to match them with the now-expanded database of geological sources. Results from our analysis of MSA obsidian artifacts from Porc-Epic Cave, Halibee, Herto, and Aduma show the utilization of more diverse obsidian sources than previously suggested, with persistent procurement from sources located within 50-150 km of the sites and rarely from sources up to 250 km away. Notably, inhabitants of K'one bypassed abundant local obsidian in favor of either other unidentified local sources or even distant ones. Conversely, the late MSA at Aladi Springs indicates a more localized obsidian procurement. The combined data challenge simple distance-decay models of lithic transport. Instead, MSA obsidian exploitation appears to have been mediated by resilient networks and 'safety-net' strategies designed to mitigate environmental risk. Such patterns also suggest a high degree of social complexity and landscape familiarity among MSA groups across the studied region.