Evrim Yazgin
Cosmos science journalist
New research reveals that Neanderthal stone tool makers had to be extremely precise about the angle at which they would strike to produce hand tools hundreds of thousands of years ago.
The study, published in the journal Archaeological and Anthropological Sciences, challenges the previously held belief that the angle of hammer strike was dependent on the stiffness of the flake and would have little effect on the shape of the stone tool.
Stone tool technology from the Middle Palaeolithic – 400,000 to 200,000 years ago – has been found in Africa, Europe and Asia. Neanderthals in this period developed a stone knapping technology now called the Levallois method.
Levallois stone tools are cut to specific sizes and shapes, indicating advanced thinking such as foresight, planning and long-term memory.
Researchers from the University of Wollongong in Australia wanted to test just how much skill and cognitive ability is required to create Levallois stone tools. They conducted controlled experiments using vices and mechanical hammers to see the impact of changing the strike angle.
They used soda-lime glass cores to replicate the material worked by ancient humans to make stone tools.
A total of 20 Levallois flakes were produced in the experiment with controlled hammer blows at angles of 0°, 10° and 20°. The flakes were then analysed. Weight, dimension, fracture trajectory and detachment force were all measured, and the flakes 3D scanned and cross-sectioned.
Flakes produced using lower strike angles were larger, heavier and thicker. The flakes were narrower and more pointed if the strike angle was greater.
The findings suggest that Neanderthal stone knappers likely used different strike angles as part of a skilled stone tool production process to control flake size, shape and pointiness. Detaching larger flakes at low angles required greater force and involved increased risk, suggesting that strike angle selection reflected active decisions balancing effort and outcome.
