The Fossils of Sterkfontein Caves
Mrs Ples, Little Foot, and nearly a century of excavation — the story of how Sterkfontein became the richest early-hominin fossil site on Earth.
Sterkfontein's fame rests on two extraordinary fossil discoveries — “Mrs Ples” in 1947 and “Little Foot”, spotted in 1994, located in the rock in 1997 and finally unveiled in 2017 — found within the same cave system that visitors walk through today. The site has yielded more than 700 hominin specimens in all. This guide traces both discoveries and explains why the Cradle of Humankind matters so much to the study of human origins.
Who discovered Mrs Ples, and why does it matter?
On 18 April 1947, palaeontologist Robert Broom and John T. Robinson uncovered a remarkably complete cranium at Sterkfontein — catalogued as Sts 5 and nicknamed “Mrs Ples” — identified as Australopithecus africanus. Its completeness made it one of the most important fossil finds in Africa at the time, offering rare, detailed evidence of an early hominin's skull structure. Broom read it as female from its small canine sockets, though most researchers now consider Sts 5 male.
Its age is genuinely unsettled. Mrs Ples was long dated to roughly 2.1 to 2.5 million years on the basis of flowstone dating, but cosmogenic nuclide dating published in PNAS in 2022 pushed the Sterkfontein Member 4 deposits back to around 3.4 to 3.5 million years — about a million years older than previously estimated — and Wits now cites roughly 3.3 million years for Mrs Ples on its research pages, while other operator material still gives 2.4 million. Broom's discovery established Sterkfontein's reputation and set the stage for decades of further excavation.
What is Little Foot, and why is it so significant?
In September 1994 Ronald Clarke identified four small hominid foot bones while sorting boxes of previously excavated material, and Phillip Tobias coined the nickname “Little Foot”. In July 1997 Clarke located the rest of the skeleton still in place in the Silberberg Grotto; freeing it from concrete-hard breccia and preparing it took some twenty more years, and the reconstructed skeleton was unveiled at Wits in December 2017. Cosmogenic dating places it at 3.67 ± 0.16 million years old.
Little Foot is recognised as the most complete early-hominin skeleton ever recovered anywhere in the world, giving researchers an unprecedented look at the skull, spine, limbs and feet of a single individual — evidence that has directly informed scientific understanding of how and when early hominins began walking upright. Its excavators assigned it to Australopithecus prometheus, though that attribution remains debated: a 2025 analysis argues the species designation is unsupported and places the specimen closer to Australopithecus africanus.
Why is the Cradle of Humankind a UNESCO World Heritage Site?
UNESCO inscribed the Cradle of Humankind in 1999, under the listing “Fossil Hominid Sites of South Africa,” recognising the exceptional density and scientific value of the fossils recovered across its cluster of caves. Sterkfontein is the most extensively excavated of these sites, having produced more than 700 hominin specimens; it is frequently credited with more than a third of all early hominin fossils found worldwide prior to 2010, though that figure is widely repeated rather than authoritatively published.
The designation reflects not just individual famous fossils like Mrs Ples and Little Foot, but the cumulative scientific record built up across nearly a century of continuous excavation — a record that continues to grow, as researchers are still working in the fossil preparation laboratory today.
What does ongoing research at Sterkfontein involve?
Excavation at Sterkfontein has never really stopped since Robert Broom's era — researchers continue to study previously excavated material and work through new finds in the on-site fossil preparation laboratory, which visitors can see as part of their ticket. The 2022 cosmogenic dating campaign, which reset the age of the whole Australopithecus assemblage here, and machine-learning analysis of tooth marks showing brown hyenas scavenged Sterkfontein hominins, both show the site remains scientifically active rather than a closed historical dig.
Since 1 April 2024 all research and visitor operations at Sterkfontein and Swartkrans have been run by the University of the Witwatersrand, which houses the world's largest hominin fossil repository. This ongoing work is part of what distinguishes a Sterkfontein visit from many other historical attractions — the story is, quite literally, still being written.
Frequently asked
When was Mrs Ples found?
Robert Broom and John T. Robinson discovered the Mrs Ples cranium — specimen Sts 5 — at Sterkfontein on 18 April 1947. It is an Australopithecus africanus specimen.
How old is Mrs Ples?
That is currently unsettled. The traditional figure was roughly 2.1 to 2.5 million years, but cosmogenic re-dating of the Member 4 deposits published in 2022 made the Sterkfontein assemblage about a million years older, and Wits now cites around 3.3 million years for Mrs Ples on its research pages.
When was Little Foot found?
Ronald Clarke identified the first foot bones in 1994 and located the skeleton in the cave in 1997; preparation took about twenty more years and it was unveiled in 2017. Cosmogenic dating places it at 3.67 million years old — the most complete early-hominin skeleton ever found.
Why is Sterkfontein called the Cradle of Humankind?
Sterkfontein sits within the Cradle of Humankind, a UNESCO World Heritage Site inscribed in 1999 recognising the exceptional concentration of early hominin fossils found across this cluster of caves in Gauteng, South Africa.
Is excavation still happening at Sterkfontein?
Yes — the on-site fossil preparation laboratory is an active research facility, and since 1 April 2024 all research and visitor operations have been run by the University of the Witwatersrand. Researchers continue to study and re-date material recovered from the site.
What species were Mrs Ples and Little Foot?
Mrs Ples is classified as Australopithecus africanus. Little Foot was assigned by its excavators to Australopithecus prometheus, but that attribution is contested — a 2025 study argues it is unsupported and places the specimen closer to A. africanus.