Functional study of basalt cleavers from Mieso (East-Central Ethiopia)

Abstract

The recent excavations at the Mieso valley in East-Central Ethiopia provided an important Middle to Upper Pleistocene palaeoanthropological sequence. The focus of this study is the functional analysis of a selection of cleavers recovered from the Middle Pleistocene deposits of Mieso, dated at around 212 ka, and considered to be among the latest evidence of the Acheulean in East Africa. Most of the large cutting tools come from Mieso 7, a stratified site primarily characterized by a small concentration of artefacts related to final stages of use and discard of large cutting tools, among which a standardized group of cleavers stands out. This study represents a methodological challenge for different reasons: the large size of the artefacts, which limit the microscopic analyses; to date, there are very few traceological studies focused on these type or artefacts (despite that some macroscopic marks have been intuitively related to use by many technologists); the raw material used, basalt, has been poorly studied from the point of view of use-wear; and the fact that the original artefacts could not be carried to the specialised use-wear laboratories. This led us to resort to the use of high resolution casts obtained from the archaeological tools, which have been studied using a combination of microscopic techniques including optical, 3D digital, confocal, and scanning electron microscopes. Complementarily, 3D scanning techniques, surface morphometric characterisation and GIS analysis have been applied to better characterise the macroscopic wear traces. In addition, a specific experimental program has been developed to reinforce the interpretation of the results coming from the archaeological materials. The preliminary results highlight the good preservation of the archaeological artefacts, allowing us to work out generic actions carried out by the analysed tools. The combination of the experimen¬tal and archaeological data supports the advantages of using a multi-technique approach, and represents a step forward on the understanding of the functional role of the cleaver as one of the Acheulean standard tool forms.