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Heat treatment significantly increases the sharpness of silcrete stone tools

Published version
Peer-reviewed

Type

Article

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Authors

Pargeter, J 
Schmidt, P 

Abstract

jats:pHumans were regularly heat‐treating stone tool raw materials as early as 130,000 years ago. The late Middle Stone Age (MSA) and Late Stone Age (LSA) of South Africa's Western Cape region provides some of the earliest and most pervasive archaeological evidence for this behaviour. While archaeologists are beginning to understand the flaking implications of raw material heat treatment, its potential functional benefits remain unanswered. Using silcrete from the Western Cape region, we investigate the impact of heat treatment on stone tool cutting performance. We quantify the sharpness of silcrete in its natural, unheated form, before comparing it with silcrete heated in three different conditions. Results show that heat‐treated silcrete can be significantly sharper than unheated alternatives, with cutting forces halving and energy requirements reducing by approximately two‐thirds. The data suggest that silcrete may have been heat treated during the South African MSA and LSA to increase the sharpness and performance of stone cutting edges. This early example of material engineering has implications for understanding Stone Age populations’ technological capabilities, inventiveness and raw material choices. We predict that heat‐treatment behaviours in other prehistoric and ethnographic contexts may also be linked to increases in edge sharpness and concerns about functional performance.</jats:p>

Description

Keywords

heat treatment, silcrete, durability, controlled experiment, stone tool function, thermal alteration, early pyrotechnology

Journal Title

Archaeometry

Conference Name

Journal ISSN

0003-813X
1475-4754

Volume Title

63

Publisher

Wiley