Dating Human Origins in South Africa

Dr Andy Herries, La Trobe University

Our African origin, as opposed to an assumed European origin, was first hinted at in 1924 following the identification of the Taung Child Australopithecus africanus fossil as a human ancestor by Australian anatomist, Raymond Dart. Dart’s discovery put South Africa at the forefront of debates about humanity’s origins as numerous ‘ape-man’ fossils were recovered from South Africa prior to World War II.

Since the discoveries of human ancestors in East Africa in 1959, notably the first specimen attributed to our genus (Homo habilis) in 1960, followed by the discovery of the famous ‘Lucy’ Australopithecus afarensis fossil from Ethiopia in 1974, the East African record has dominated our understanding of the origin of humans. This is in part due to our ability to accurately date the volcanic sequences of East Africa using methods such as Potassium-Argon/Argon-Argon dating, and, until recently, our inability to precisely date the South African fossil record. The proven time depth of hominin fossils in Eastern and central Africa at 7-6 Ma has also been a major factor. However, major advances in multiple geochronological methods (Palaeomagnetism, Electron Spin Resonance, Uranium-series and cosmogenic nuclide dating) in the last 10 years now make the dating of Plio-Pleistocene cave deposits and thus of the South African fossil record a reality.

A renewed interest in South African palaeoanthropology with an amazing rate of discovery of new hominin fossils has developed in tandem with these advances in dating techniques.

Moreover, recent discoveries have shown that the South African record has preserved entire skeletons (adult and juvenile) of these early hominins in a way that is extremely rare in East Africa. This research has shown that South and East Africa are very different regions in which hominins that look similar in many ways and have been classified as the same genera, have adapted to the very different environments in novel ways.

In 2008, the discovery of a new hominin species Australopithecus sediba, dated by Prof Herries and other Australian colleagues, again raised the question of whether South Africa, rather than East Africa, could be the origin of humans in terms of our Genus, Homo. However, a new fossil discovered by Prof Herries and his colleagues and dated just this year may show that our genus was living in South Africa contemporaneously with Au. sediba. These debates have begun to raise questions about how we define our Genus and they are beginning to show that the period between 3 and 2 million years ago, when more ape-like species (Australopithecus) gave rise to the first of our Genus (Homo ergaster), was extremely complex.

Prof Herries’ talk will examine these debates and outline the current methods and strategies for accurately excavating, analysing and dating the complex palaeocaves that contain the vast majority of human fossils from southern Africa.