Despite eastern Africa being a key location in the emergence of Homo sapiens and their subsequent dispersal out of Africa, there is a paucity of long, well-dated climate records in the region to contextualize this history. To address this issue, we dated a ∼293 m long composite sediment core from Chew Bahir, south Ethiopia, using three independent chronometers (radiocarbon, 40Ar/39Ar, and optically stimulated luminescence) combined with geochemical correlation to a known-age tephra. The site is located in a climatically sensitive region, and is close to Omo Kibish, the earliest documented Homo sapiens fossil site in eastern Africa, and to the proposed dispersal routes for H. sapiens out of Africa. The 30 ages generated by the various techniques are internally consistent, stratigraphically coherent, and span the full range of the core depth. A Bayesian age-depth model developed using these ages results in a chronology that forms one of the longest independently dated, high-resolution lacustrine sediment records from eastern Africa. The chronology illustrates that any record of environmental change preserved in the composite sediment core from Chew Bahir would span the entire timescale of modern human evolution and dispersal, encompassing the time period of the transition from Acheulean to Middle Stone Age (MSA), and subsequently to Later Stone Age (LSA) technology, making the core well-placed to address questions regarding environmental change and hominin evolutionary adaptation. The benefits to such studies of direct dating and the use of multiple independent chronometers are discussed. © 2021 Elsevier Ltd
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We thank staff at the Oxford Radiocarbon Accelerator Unit, in particular Richard Staff, David Chivall and Victoria Cullen, as well as Patrick Robson for pollen and charcoal separation. Annett Junginger performed the fish bone collection during the “sampling party” at LacCore, Minneapolis, in spring 2015. We thank Anders Noren, Kristina Brady, Mark Shapley, and Brian Grivna, of LacCore for their support throughout the project. Victoria Cullen and Alma Piermattei provided technical assistance with tephra analyses; Victoria Smith and Iris Buisman gave support with EPMA. Hollie Wynne provided vital technical assistance in the Aberystwyth Luminescence Research Laboratory. We are grateful to Yonas Beyene who allowed us access to the Konso tephra localities. We acknowledge many local, regional and Federal authorities in Ethiopia for providing permits for scientific drilling in the Chew Bahir Basin, and for facilitating actual drilling operations as well as sample export. Céline Vidal was supported by a Leverhulme Trust grant (Nature and impacts of Middle Pleistocene volcanism in the Ethiopian Rift; 2016-20). The work described here is part of the Hominin Sites and Paleolakes Drilling Project (HSPDP) funded by grants from ICDP , NSF ( EAR1338553 ; BCS-1322017; EAR-2020044 ), NERC ( NE/K014560/1 ) and DFG (Priority Program SPP 1006 ; SCHA 472/13 and/18 ; TR 419/8, /10 and /16 ) and the CRC 806 Research Project number 57444011 “Our Way to Europe”. This is publication #38 of the Hominin Sites and Paleolakes Drilling Project.
© 2021 Elsevier Ltd
- 40Ar/39Ar dating
- Optically stimulated luminescence
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