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Browsing Research Articles (Lee Berger Collection) by Keyword "age"
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 Homo naledi
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 H.
naledi 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 222Rn 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 Homo naledi fossils, we have
constrained the depositional age of Homo naledi to a period between 236 ka and 335 ka. These
age results demonstrate that a morphologically primitive hominin, Homo naledi, survived into the
later parts of the Pleistocene in Africa, and indicate a much younger age for the Homo naledi fossils
than have previously been hypothesized based on their morphology.