STS 5
Exhibit item
Nickname: 
Mrs. Ples
Site: 
Sterkfontein, Republic of South Africa
Date of discovery: 
1947
Discovered by: 
Robert Broom and John T. Robinson
Age: 
Between 2.5 and 2.1 million years old

Not predator, but prey

STS 5, a nearly complete adult Australopithecus africanus, was an important fossil find because skeptics had previously argued that the Taung Child was actually a baby chimpanzee that would have gained its ape-like features when it got older. This fossil showed that maturity wouldn’t make A. africanus less human. The main difference between STS 5 and the Taung Child is that this fossil's face is strongly prognathic, an ape-like feature that becomes more pronounced as A. africanus individuals grow up.

STS 5 was nicknamed 'Mrs. Ples' by scientist Robert Broom after initially hypothesizing that she was a middle-aged female Plesianthropus transvaalensis, which was the original name of this species---thus, ’Mrs. Ples.’ This skull now thought to have belonged to a male.

Often found alongside animal bones, Australopithecus africanus was once considered a “killer ape.” Now we know that members of this early human species were sometimes eaten by predators. Living together in groups helped these early humans protect themselves.

Why dynamite is not necessarily the best way to excavate human remains.... do you see the wedge-shaped portion of the forehead reconstructed here in a light color? If you follow that crack around to the rear of the skull, you’ll see why scientists are much more careful today when excavating, or digging for human remains. Mrs. Ples’ skull was actually blown into two pieces during its extraction from the breccia (a cement-like rock) because Broom used dynamite to expose the remains over backbreaking work with a pickaxe.

Image of STS 5 skull, 3/4 view