Stone tools in South Africa reveal early human communication

Perched high above the ocean on South Africa’s southern coast, a cave carved into a cliff has revealed thousands of ancient stone tools left behind by early humans some 20,000 years ago.

Through painstaking excavation and detailed analysis, a team of archaeologists has uncovered clues not only about how these tools were made, but also how people in the late ice age traveled, interacted, and passed along their techniques – suggesting a web of shared knowledge stretching across southern Africa.

The findings center on the Robberg technocomplex, a group of stone tool technologies used between 24,000 and 12,000 years ago. The study was led by Sara Watson, a postdoctoral scientist at the Field Museum’s Negaunee Integrative Research Center.

For Watson, the research offers a compelling window into the behavior of early Homo sapiens. “This is an important insight into how people who lived in this region were living and hunting and responding to their environment,” she said.

Stone tools during the ice age

At the time the tools were crafted, the world was emerging from the last major ice age. With massive volumes of water locked in glaciers and ice sheets, global sea levels were much lower than today.

What is now a coastal cave overlooking the ocean would have stood several miles inland, adjacent to vast plains teeming with game.

“Instead of being right on the water like they are today, these caves would have been near vast, open plains with large game animals like antelope,” Watson said. “People hunted those animals, and to do that, they developed new tools and weapons.”

Today, however, the geography is strikingly different. The caves are embedded in a steep cliff face, towering nearly 75 feet above a rugged shoreline. Reaching the excavation site required determination – and serious safety equipment.

“It’s a 75-foot climb up to the cave from the shoreline,” Watson explained. “We had safety ropes and a staircase made of sandbags, and we had to be harnessed in while doing the excavation.”

Cores of ancient stone tools

Despite the challenges, the team hauled up all their excavation gear – sometimes 50 pounds per person – and carried out meticulous work using small dental tools and tiny trowels.

“Since these are extremely, extremely old sites, from before the end of the last ice age, we had to be very careful with our excavation,” Watson added.

Beneath layers of dust and sediment, the team unearthed a wealth of artifacts: thousands of sharp, small blades and the larger rocks – known as cores – from which those blades were struck.

While the blades may attract the most attention, it’s the cores that Watson finds most illuminating.

“When your average person thinks about stone tools, they probably focus on the detached pieces, the blades and flakes. But the thing that is the most interesting to me is the core, because it shows us the particular methods and order of operations that people went through in order to make their tools,” she said.

Stone tools and communication

By closely analyzing the patterns etched into the surfaces of these cores, Watson and her colleagues identified distinct methods of reduction – techniques used to produce the desired blade shapes. These methods are not random.

Instead, they reflect intentional, culturally shared ways of making tools that were likely passed from one generation to the next.

“In a lot of these technologies, the core reduction is very specific, and it’s something that you are taught and learn, and that’s where the social information is,” Watson noted.

“If we see specific methods of core reduction at multiple sites across the landscape, as an archaeologist, it tells me that these people were sharing ideas with one another.”

Shared traditions across hundreds of miles

One of the most telling discoveries in the Robberg cave was a particular technique for breaking small bladelets off a core – a method that has also been identified at archaeological sites hundreds of miles away in countries such as Namibia and Lesotho.

“Same core reduction pattern, same intended product,” Watson said. “The pattern is repeated over and over and over again, which indicates that it is intentional and shared, rather than just a chance similarity.”

These repeated techniques suggest that early humans in different regions were not isolated but part of a broader network of knowledge-sharing. Whether through seasonal migration, trade, or cultural exchange, they were likely communicating in ways that helped spread innovations across vast distances.

A human story etched in stone

According to Watson, although the tools may be ancient, the people who made them were not so different from us. “We have a very long and rich history as a species, and humans go back a lot farther in time than most people realize,” she said. “People living around the last ice age were very similar to people today.”

The blades and cores from the Robberg caves tell more than a story of survival – they illustrate the complexity and adaptability of early human societies. They hint at long-distance connections, sophisticated knowledge transfer, and the ability to innovate in response to a changing world.

As researchers continue to dig into these layers of prehistory, each artifact recovered offers a new piece of the puzzle – an enduring link between our ancestors and the modern world.

The study is published in the Journal of Paleolithic Archaeology.

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