Mrs Ples is a skull found at the Sterkfontein Caves near Krugersdorp (Transvaal) by Dr Robert Broom and John Robinson in April 1947. They were both palaeontologists from the Transvaal Museum at the time. The skull is the most complete cranium of the species Australopithecus Africanus which is believed to be the common ancestor for all humankind. Another fossil, the "Taung child", was discovered in 1924, and also belongs to the genus, Australopithecus.
Later, after further study, Broom decided that although both species displayed combinations of ape-like and human features, the Sterkfontein specimen was still very different from the Taung fossil, especially in certain features of the teeth. He regarded it as a representative of a different genus, Plesianthropus (hence Mrs Ples). Still later, it was decided that all the Sterkfontein fossils should be no longer generically or specifically distinct from the species represented by the Taung fossil. They should all be called, Australopithecus Africanus Transvaalensis. This implied that the Sterkfontein specimen belonged to the same species as the Taung fossil, but to a different subspecies or race. The generic name, plesianthropus is no longer in use.
Mrs Ples lived about 2,5 million years ago. At that time the Transvaal highveld consisted of woodland, forest vegetation and grassland. By studying past environments we are better able to understand the factors which contributed to the emergence of a Mrs Ples and the skull of a chimpanzee new species and also why certain species became extinct. Mrs Ples' brain size was small, similar in size to the chimpanzee, but she was able to walk upright. Also she did not have projecting canines as chimpanzees do. Furthermore there was no gap between her canines and incisors, as in chimpanzees. In this respect she is more closely related to humans than chimpanzees.
Charles Darwin had mentioned certain similarities between humans and chimpanzees. He predicted that fossils would one day be found on the African continent, to indicate that humans and chimpanzees had a common ancestor a long time ago. It is suspected that a common ancestor for humans and chimpanzees may have lived on the African continent roundabout five million years ago.
Mrs Ples, often referred to as The Missing Link, is perhaps only one of many links in the evolutionary chain.
A common view amongst scientists is that Australopithecus is the genus from which all species of the genus, Homo evolved. They differ in opinion as to how some of the species of Homo evolved and as to where the boundaries between such species occurs. Most reckon that Australopithecus Africanus (Mrs Ples) led to the evolvement of Homo habilis, "handy man" (about 1,8 million years ago), which in turn led to Homo erectus (1 million years ago). And finally Homo sapiens, "wise man" - the homonid species of today evolved.
At the Transvaal Museum in Pretoria, we are reminded that without the ingenuity of the Mrs Ples' of yesteryear, many of our technological advances would not have been possible. Mrs Ples and co. had the ability to control the use of fire. Modern man used this knowledge to develop rocket engines and rockets made it possible to get to the moon and outer space.