Abstract:
Stone artifacts are the most prevalent pieces of evidence for studying prehistoric hominin behaviors. The emergence and development of stone tool technology delineate the trajectory of human evolution and are argued to represent a distinctive form of hominin culture in comparison with other species. Reconstructing hominins’ technical decisions from the archaeological record of stone tools is an important approach for studying their behavior and cognition. Much has been learned in this regard using approaches such as reconstructing reduction sequences, analyzing the morphological characteristics of the stone artifacts, identifying raw material procurement patterns, and analyzing use-wear patterns. However, how early hominins managed various force delivery variables, in other words how they struck off flakes, is still not well understood because these variables are difficult to directly measure from the archaeological record.
This thesis sets out to investigate one such force delivery variable, namely the angle of blow (i.e., the angle at which the hammer strikes the core’s platform for flake removal) using an experimental approach. Controlled flaking experiments have increasingly become crucial in lithic studies by virtue of their ability to quantify knapping behaviors into measurable lithic attributes. Controlled experiments are improving and evolving to create a robust framework for archaeologists to form and test different hypotheses related to the production and use of stone tools while generating reproducible results.
The structure of this thesis is threefold. First, I review and synthesize what we know about flake formation from previous controlled flaking experiments (Chapter 2). Second, I design a controlled experiment guided by principles coming from fracture mechanics to study the effect of the angle of blow on flake formation and to establish a way to measure it on flakes (Chapter 3). The experimental results show that the angle of blow is visible and measurable on a feature of the bulb of percussion that I name the bulb angle. Third, I use the bulb angle measurement coming from the controlled experiment to measure flakes from a series of Early Pleistocene assemblages to investigate how early hominins managed their angles of blow during knapping (Chapter 4). I find evidence that early hominins began to appreciate the impact of angle of blow through the application of a more systematic control over the angle of blow towards the Oldowan-Acheulean transition.
The experimental approach applied here illustrates how important insights can be gained to complement the more traditional technological approaches for studying hominins’ technical capabilities. The results of this thesis 1) show the usefulness of controlled experimentation in lithic studies and the importance of designing experiments that can effectively link knapping behaviors to measurable lithic attributes, drawing on information from fracture mechanics; 2) show a temporal progression in early hominins’ understanding and control over the angle of blow through time; and thereby 3) provide insights into the evolution of early hominin behavior and cognition, which in turn has the potential to help clarify debates over the onset of cumulative culture in human prehistory.
Knapping actions