Design and development of a sensorized hammerstone for accurate force measurement in stone knapping experiments

Area of Science:

• Paleoanthropology
• Archaeological Science
• Biomechanics

Background:

• Stone tool knapping is a key hominin behavior involving upper limb mechanics and percussive force application.
• Understanding the evolution of tool-making requires quantifying the forces involved in stone knapping.
• Direct measurement of forces during knapping has been a significant experimental challenge.

Purpose of the Study:

• To introduce a novel, ergonomic synthetic hammerstone capable of recording percussive forces during stone knapping experiments.
• To provide an experimental tool for investigating the biomechanics of stone tool production.
• To facilitate research into the relationship between anatomical and technological changes in human evolution.

Main Methods:

• Development of a synthetic hammerstone with a deformable pneumatic chamber and integrated sensor.
• Calibration of the synthetic hammerstone by comparing recorded pressure data with force plate measurements.
• Validation of the hammerstone's accuracy through anvil-supported knapping experiments on glass.

Main Results:

• The synthetic hammerstone accurately quantifies percussive forces during knapping.
• Experimental validation achieved a root mean square error under 6% for forces up to 730 N.
• The hammerstone's accuracy was not significantly affected by striking angle variations up to 15°.

Conclusions:

• The developed synthetic hammerstone offers a reliable method for measuring forces in stone knapping.
• This tool enables direct investigation of the role of percussive force in hominin technological evolution.
• Future studies can now directly link biomechanical data to the emergence of stone tool behaviors.