Sterkfontein Cave near Krugersdorp in Gauteng has produced more pre-human australopithecine fossil specimens (more than 500) than any other single site in the world. The best-known specimen is the almost complete skull of ‘Mrs Ples’, as it was dubbed by the media at the time of discovery.
The work on early hominid fossils that was started at Sterkfontein by Dr Robert Broom, following on Professor Ray mond Dart’s discoveries at Taung in 1924, was carried forward in the second half of the twentieth century mainly by Professor Phillip Tobias of the Department of Anatomy at the University of the Witwatersrand and Dr C.K. (Bob) Brain of the Transvaal Museum. Soon after South Africa signed the World Heritage Convention in the late 1990s, a cluster of early hominid sites around Sterkfontein, Swartkrans, Kromdraai and neighbouring properties in Gauteng Province west of Johannesburg were nominated and accepted as a World Heritage Site. Since then, the sites at Taung in North West Province and Makapan in Limpopo Province have been added to what is colloquially known as the Cradle of Humankind. Stone tools have been found in the younger layers at some of the same sites, showing that in addition to australopithecines, true humans lived and died there.
All the fossils have been preserved because the bones were deposited between four and one million years ago in lime-rich soils, mostly in erosion cavities in dolomite. Brain’s research proved that the australopithecines and many of the other animals whose bones were fossilised in the dolomite were mainly the prey of large carnivores, such as the extinct Dinofelis. Burnt bones found at Swartkrans in a layer that includes early human remains suggest that people sheltering in the cavern had learned to use fire at least a million years ago and this may have helped them to compete with carnivores.
One of the most interesting fossils is the so-called ‘Little Foot’. It is older than most of the other australopithecines – about 3.2 million years – and was identified first from its foot bones, which showed it was still partly ar boreal. Some careful detective work by Nkwane Molefe and Stephen Motsumi, at the request of Dr Ron Clarke, found the rest of the bones of the skeleton still embedded in the breccia that filled the dolomite cavern at Sterkfontein. The fact that the skeleton is almost complete suggests that this individual was not killed by a carnivore, but possibly fell into a deep cavity and was unable to get out.
These sites create a unique window on the past because of the rare conditions that preserved the bones. Interpretative centres at Sterkfontein and at Maropeng display some of the fossils and explain their significance.
