Shaking up the family tree: Uranium-lead dating human origins in South Africa
Dr Robyn Pickering, from the Department of Geological Sciences, will present the Faculty of Science Special Research Seminar, with a talk entitled, "Shaking up the family tree: Uranium-lead dating human origins in South Africa".
All the earliest human fossil (hominin) remains are found in Africa, from the very beginnings of our own genus Homo around 2 million years ago, through to the first sign of modern human behaviour at around 164 thousand years ago. The caves near Johannesburg known as the ‘Cradle of Humankind’ are one of the richest sources of this evidence. Knowing how old the fossils are is critical to placing them in our human ‘family tree’ and until recently the South African deposits had never been thoroughly dated. The geochemical technique of Uranium-Lead dating of the cave deposits themselves, particularly the speleothem or flowstone layers, sandwiched between the fossil bearing sediments, is proving to be a powerful tool. The discovery of a new species of early hominin, Australopithecus sediba, in late 2008 and the subsequent dating of these fossils to 1.977±0.003 million years old has shaken up the long held view of our human family tree – this species may be our oldest direct ancestor. The application of this technique to other types of deposits, such as the open-air sites up the west coast of the Western Cape, is beginning to shed new light into how these sites formed.
Dr. Robyn Pickering is a recently appointed lecturer in the Department of Geological Sciences at UCT. She is an isotope geochemist interested in palaeoanthropology and archaeology, and her research agenda involves understanding where and when our early human ancestors evolved, and the environment(s) in which they lived. Dr. Pickering works mainly on South African early hominin caves sites, and is the dating specialist on several large international teams, working on archaeological and palaeoanthropological sites on the southern and western coasts of South Africa, Australia, East Africa, Armenia, and the Dominican Republic. She has spent the last decade developing the Uranium-series dating technique, and part of her mandate at UCT is the establishment of this approach in pre-existing laboratory facilities in the Department of Geological Sciences. Dr. Pickering was recently awarded a highly prestigious P rating by the NRF.