The age of Homo naledi and associated sediments in the Rising Star Cave, South Africa

• Published in: eLife 2017-05, Vol.6
• Main Authors: Dirks, Paul Hgm, Roberts, Eric M, Hilbert-Wolf, Hannah, Kramers, Jan D, Hawks, John, Dosseto, Anthony, Duval, Mathieu, Elliott, Marina, Evans, Mary, Grün, Rainer, Hellstrom, John, Herries, Andy Ir, Joannes-Boyau, Renaud, Makhubela, Tebogo V, Placzek, Christa J, Robbins, Jessie, Spandler, Carl, Wiersma, Jelle, Woodhead, Jon, Berger, Lee R
• Format: Article
• Language: English
• Subjects: Age; Animals; Bone and Bones; Dating; Dinaledi Chamber; Earth science; Electron spin resonance; Fossils; Genomics and Evolutionary Biology; Geologic Sediments; Geology; Geology - methods; Graphite; Hominidae; hominin; Homo naledi; Laboratories; paleoanthropology; Paleontology - methods; Pleistocene; Radiometric Dating; Sediments; South Africa; Teeth
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/elife.24231

New ages for flowstone, sediments and fossil bones from the Dinaledi Chamber are presented. We combined optically stimulated luminescence dating of sediments with U-Th and palaeomagnetic analyses of flowstones to establish that all sediments containing fossils can be allocated to a single stratigraphic entity (sub-unit 3b), interpreted to be deposited between 236 ka and 414 ka. This result has been confirmed independently by dating three teeth with combined U-series and electron spin resonance (US-ESR) dating. Two dating scenarios for the fossils were tested by varying the assumed levels of Rn loss in the encasing sediments: a maximum age scenario provides an average age for the two least altered fossil teeth of 253 +82/-70 ka, whilst a minimum age scenario yields an average age of 200 +70/-61 ka. We consider the maximum age scenario to more closely reflect conditions in the cave, and therefore, the true age of the fossils. By combining the US-ESR maximum age estimate obtained from the teeth, with the U-Th age for the oldest flowstone overlying fossils, we have constrained the depositional age of to a period between 236 ka and 335 ka. These age results demonstrate that a morphologically primitive hominin, survived into the later parts of the Pleistocene in Africa, and indicate a much younger age for the fossils than have previously been hypothesized based on their morphology.