Archaeologists from the Field Museum unearthed thousands of ancient stone tools in a cave overlooking the ocean on the southern coast of South Africa, revealing sophisticated fabrication techniques developed by Ice Age humans approximately 20,000 years ago. The discovery sheds new light on how prehistoric people lived, interacted, and responded to their environment at the end of the last major ice age.
The tools were crafted between 24,000 and 12,000 years ago, during a time when Earth was vastly different due to lower sea levels caused by frozen glaciers and ice caps. The region that is now the coast of South Africa was several miles inland, and the caves where the tools were found were situated near expansive plains teeming with large game animals like antelope.
"This is an important insight into how people who lived in this region were living and hunting and responding to their environment," said Sara Watson, a postdoctoral scientist at the Field Museum's Negaunee Integrative Research Center and lead author of the study published in the Journal of Paleolithic Archaeology. She added, "People living around the last ice age were very similar to people today."
Accessing the caves was a challenge for the research team, requiring a 75-foot climb using safety ropes and climbing harnesses. "We had safety ropes and a staircase made of sandbags, and we had to be harnessed in while doing the excavation," Watson explained. Every day, she and her colleagues ascended the sandbag staircase with all their equipment for excavation and photography, making multiple trips while carrying 50-pound backpacks.
"Since these are extremely old sites from before the end of the last ice age, we had to be very careful with our excavation," Watson noted. "We used small dental tools and mini-shovels to remove each layer of deposits," she said.
Beneath the ancient dust and dirt, the team discovered thousands of stone tools, including small, sharp blades known as bladelets, as well as larger pieces of rock called cores from which these blades were chipped. By studying tiny details on the flakes of blades and stones, the archaeologists were able to determine how the tools were made.
"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," Watson explained. She and her colleagues observed several distinct patterns in the way the cores had been reduced into smaller blades.
One specific method of breaking tiny bladelets off a core, found in the Robberg caves, resembles a style discovered hundreds of miles away in Namibia and Lesotho. "Same core reduction pattern, same intended product. The pattern is repeated over and over and over again, which indicates that it is intentional and shared, rather than just a chance similarity," Watson said. "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."
These findings suggest that Paleolithic people shared tool-making knowledge across distances, possibly through traveling and interacting with different groups. "The precision of the blade-making methods and the variety of techniques used led us to hypothesize that the Paleolithic people shared tool-making knowledge with each other and perhaps even learned from other groups," Watson noted.
The physical challenges and painstaking excavation efforts yielded new clues about how prehistoric people may have lived and interacted. "They may have used the site a little bit differently, too. Rather than people living at the site full time, it's possible that this may have been more of a temporary camp," Watson suggested.
The article was written with the assistance of a news analysis system.
