Chronological and behavioral contexts of the earliest Middle Stone Age in the Gademotta Formation, Main Ethiopian Rift

There is a general consensus that our species emerged first in Africa. Currently, the best-known skeletal evidence for the earliest anatomically modern Homo sapiens (AMHs) derives from sites in the rift valley in Ethiopia. However, archaeological evidence from cave sites in southern and northern Africa largely dominates discussions on behaviors that characterize the dawn of modern humans. Later Middle Pleistocene open-air sites in East Africa present unparalleled geochronological control and thus a better chance to study hominin behavior. Here, we present results of a multidisciplinary investigation of the archaeology and geochronology of one of the oldest-known Middle Stone Age (MSA) occupations from the Gademotta Formation (Fm.) in the Main Ethiopian Rift. Renewed excavation, lithic analysis, fracture mechanics, and tephrochronological investigations at Gademotta provide a better understanding of the chronological and behavioral contexts during the critical period immediately preceding the origin of our species.