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.DOI: http://dx.doi.org/10.7554/eLife.24231.001

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The Makgadikgadi Basin in Botswana hosts a system of salt lakes, which developed from the Upper Pleistocene onward due to the gradual shrinking of the giant Lake Palaeo-Makgadikgadi. Stratigraphic and palaeoclimatic studies of this area are difficult due to the influence of several factors, such as a complex history of regional tectonic activities, as well as climatic changes coupled with dryland diagenetic processes. This lake, in the central Kalahari, is the key to understanding the climatic variability in the southern part of Africa in the Quaternary and has played an important role in the evolution of numerous taxa, including our own. In this study, detailed sedimentological analyses (grain size and major elements distribution) of shallow sediments from the Makgadikgadi Pans were combined with the first comprehensive study of the encountered ostracod fauna to establish trends in the environmental changes in the area from the late Quaternary. Ostracod fossil assemblages from the cores of the Makgadikgadi Pans are dominated by the Limnocythere ssp., an opportunistic taxa commonly colonizing the littoral areas of shallow evaporative, ephemeral lakes, together with the subordinate occurrences of Sarcypridopsis ochracea, Sclerocypris cf. bicornis, Candonopsis spp., and Ilyocypris spp. The sediments from the pans show fluctuations in the Cl/K and Ca/Cl ratios, often in phase with the relative abundance of Limnocythere suggesting a cyclicity induced by changes of salinity and alkalinity in the water. This multi-proxy study of the cores collected from the pans suggests a Late Pleistocene shallow, playa lake environment with strongly alkaline water, interrupted by a prolonged drought with sustained aeolian conditions between ∼16 and 2 ka BP. Increasing diversity of ostracod fauna in the top 20–30 cm of the cores indicates that a temporary shift toward higher humidity occurred around 2–1.5 ka BP and lasted through the Medieval Warm Period. This humid period was followed by an overall desiccation trend that started with the Little Ice Age and continues until the present day.

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