An Ancient Engineering Lab
In a series of caves at Pinnacle Point, on the southern coast of South Africa, archaeologists uncovered evidence of surprisingly advanced technology. Around 71,000 years ago, Middle Stone Age people were systematically selecting a specific type of rock, called silcrete, and carefully heating it in controlled fires. This process, known as heat treatment, changes the stone's internal structure, making it harder, tougher, and easier to flake with precision. The people at Pinnacle Point had discovered that by heating silcrete—likely by burying it under a fire at temperatures around 600 degrees Fahrenheit—they could produce superior raw material for their tools.
The primary products of this early pyrotechnology were small, sharp bladelets, also known as microliths. These tiny stone blades, often less than 10 millimeters wide, were components of more complex composite tools. They could be hafted onto wood or bone to create projectile weapons like arrows or throwing spears. This technology is a significant cognitive leap, requiring long chains of production and a deep understanding of material properties. Evidence for this heat treatment process appears as early as 164,000 years ago at Pinnacle Point, becoming a dominant technology at the site by about 72,000 years ago. This timeline places the innovation tens of thousands of years before similar techniques appeared elsewhere in the world.