Ages of Late Middle Stone Age Sites at Shinfa in the Horn of Africa

Anatomically modern Homo sapiens left Africa during the Middle Stone Age (MSA). Although the dispersal point is broadly believed to be the Horn of Africa, with a route either north within Africa (Nile River or Red Sea coast), or east across the Red Sea at the Bab el Mandeb Strait, few sites are known from this region. We report a series of late MSA sites in the Horn on the lowland slope of Ethiopia’s northwestern plateau along the upper reaches of the Shinfa River, a Blue Nile tributary. These open air sites are usually in proximity to ancient river channels. Absolute dating using optically stimulated luminescence (OSL) of feldspars, electron spin resonance (ESR) on mammal teeth, and accelerator mass spectrometry carbon dating (AMS 14C) on ostrich eggshell (OES) together show a consistent pattern of ages, with river incision producing younger terrace deposits. A series of AMS 14C dates at SM1, an excavated locality, show that this site dates from 31–46 cal ka BP, while OSL and ESR dates suggest older occupations at higher terraces. These ages permit comparisons with local and global climatic records and provide support for the idea that these late MSA populations were riverine-based foragers.