1Anthropology, The University of Texas at Austin, 2Anthropology, The University of North Carolina at Greensboro, 3Earth Sciences, Southern Methodist University, 4Anthropology, Colorado State University
March 27, 2015 , Gateway Ballroom 4
Ongoing paleoanthropological research in northwest Ethiopia along the Shinfa river, a tributary of the Blue Nile, has recovered evidence of riverine foraging by Middle Stone Age (MSA) populations. Surface collection and excavation along the ancient river channels has yielded MSA lithics in association with a substantial ichthyofauna, mollusks, reptiles, and mammals. The modern climate at Shinfa is highly seasonal, with brief, intense wet seasons and protracted, extremely arid dry seasons. High-energy, bankfull river flows during the wet season make exploitation of aquatic fauna prohibitive. However during the dry season, when evaporative processes reduce the river to a series of waterholes, modern populations living nearby can effectively exploit the river’s resources. Preliminary isotopic data suggests that a seasonal environment may have also existed during the Late Pleistocene when MSA people occupied the area. Stable carbon and oxygen isotope values recovered from isolated spot sampling of fossil bovid enamel (n=13) indicate that this sample was dominated by C4 feeders whose crowns formed, at least partially, in a warm, arid environment. In addition, serial sampling along the growth axis of the tooth was undertaken on both fossil (n=5) and extant (n=3) bovids from Shinfa. Serial sampling revealed δ18O values and sinusoidal patterns of intratooth variation that are consistent with a shift from wet to dry seasonal environments during crown formation. We hypothesize that, similar to populations living in the Shinfa area today, MSA people occupying the area were best able to exploit available riverine resources during dryer climatic periods.
Supported by NSF grant 0921009 to J. Kappelman.