Integrative geochronology calibrates the Middle and Late Stone Ages of Ethiopia's Afar Rift
Abstract
The Halibee member of the Upper Dawaitoli Formation of Ethiopia's Middle Awash study area features a wealth of Middle and Later Stone Age (MSA and LSA) paleoanthropological resources in a succession of Pleistocene sediments. We introduce these artifacts and fossils, and determine their chronostratigraphic placement via a combination of established radioisotopic methods and a recently developed dating method applied to ostrich eggshell (OES). We apply the recently developed ²³⁰Th/U burial dating of OES to bridge the temporal gap between radiocarbon (¹⁴C) and ⁴⁰Ar/³⁹Ar ages for the MSA and provide ¹⁴C ages to constrain the younger LSA archaeology and fauna to ∼24 to 21.4 ka. Paired ¹⁴C and ²³⁰Th/U burial ages of OES agree at ∼31 ka for an older LSA locality, validating the newer method, and in turn supporting its application to stratigraphically underlying MSA occurrences previously constrained only by a maximum ⁴⁰Ar/³⁹Ar age. Associated fauna, flora, and Homo sapiens fossils are thereby now fixed between 106 ± 20 ka and 96.4 ± 1.6 ka (all errors 2σ). Additional ⁴⁰Ar/³⁹ results on an underlying tuff refine its age to 158.1 ± 11.0 ka, providing a more precise minimum age for MSA lithic artifacts, fauna, and H. sapiens fossils recovered ∼9 m below it. These results demonstrate how chronological control can be obtained in tectonically active and stratigraphically complex settings to precisely calibrate crucial evidence of technological, environmental, and evolutionary changes during the African Middle and Late Pleistocene.
Additional Information
© 2021 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND). Contributed by Tim D. White, October 15, 2021 (sent for review September 3, 2021; reviewed by Shigehiro Kato and Clark Spencer Larsen). We thank the dozens of Ph.D.-level scientists and support staff conducting field and laboratory research in the Middle Awash since 1981 (full listing at https://middleawash.berkeley.edu/). We thank the Authority for Research and Conservation of the Cultural Heritage and the National Museum of Ethiopia, the Afar Regional Government, and the Afar people of the Middle Awash, as well as the many others who contributed directly to the research efforts and results since 1981. Support from the John Templeton Foundation is gratefully acknowledged. This work was further supported in part by the Institute of Geophysics and Planetary Physics of the Los Alamos National Laboratory, Digital Globe, the Japan Society for the Promotion of Science, and donors to the Human Evolution Research Center. E.M.N. and W.D.S. were supported by NSF Grant BCS-1727085 to W.D.S. and C.A. Tryon and by the Ann and Gordon Getty Foundation, with thanks to Christina Polito-Halter and Brian Jones for help with ²³⁰Th/U analyses and Luis-Erick Aguirre Palafox and Chihiro Ishida for geochronological sample preparation assistance. W.K.H. acknowledges support from the Janet and Elliot Baines Professorship at Miami University (2010-15); M.F.B. acknowledges support from the University of California, Berkeley Chancellor's Fellowship and University of California, Berkeley Portuguese Studies Program; Y.S. and Y.B. acknowledge support from the L.S.B. Leakey Foundation and the Paleontological Scientific Trust for archaeological fieldwork and laboratory analyses, including obsidian geochemistry. Any opinions, findings, and conclusions expressed in this study are those of the authors and do not necessarily reflect the views of the granting agencies or institutions named above. Data Availability: All study data are included in the article and/or supporting information. Author contributions: E.M.N., G.W., W.D.S., B.A., Y.B., and T.D.W. designed research; E.M.N., G.W., W.K.H., P.R.R., W.D.S., M.S.S., S.H.A., B.A., Y.B., M.F.B., J.P.C., Y.S., and T.D.W. performed research; E.M.N., W.K.H., P.R.R., W.D.S., and T.D.W. contributed new reagents/analytic tools; E.M.N., G.W., W.K.H., P.R.R., W.D.S., M.S.S., S.H.A., B.A., Y.B., M.F.B., J.P.C., Y.S., and T.D.W. analyzed data; and E.M.N. and T.D.W. wrote the paper. Reviewers: S.K., Hitoto Shizenno Hakubutsukan; and C.S.L., The Ohio State University. The authors declare no competing interest. This article contains supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2116329118/-/DCSupplemental.Attached Files
Published - e2116329118.full.pdf
Supplemental Material - pnas.2116329118.sapp.pdf
Supplemental Material - pnas.2116329118.sd01.xlsx
Files
Additional details
- Eprint ID
- 112244
- Resolver ID
- CaltechAUTHORS:20211207-803172800
- John Templeton Foundation
- Los Alamos National Laboratory
- Digital Globe
- Japan Society for the Promotion of Science (JSPS)
- Human Evolution Research Center
- BCS-1727085
- NSF
- Ann and Gordon Getty Foundation
- Miami University
- University of California, Berkeley
- Leakey Foundation
- Paleontological Scientific Trust
- Created
-
2021-12-07Created from EPrint's datestamp field
- Updated
-
2021-12-07Created from EPrint's last_modified field