The reality of reduction experiments and the GIUR: reply to Eren and Sampson

Citation: Peter Hiscock, Chris Clarkson (2009) The reality of reduction experiments and the GIUR: reply to Eren and Sampson. Journal of Archaeological Sciences (RSS)
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Summary

Context

Hiscock and Clarkson [re]assert the reliability of the geometric index of unifacial stone tools reduction (GIUR) compared to different approaches to measure flake mass removed from retouched flakes. This article is a direct response to Eren and Sampson’s claims in “Kuhn's geometric index of unifacial stone tool reduction (GIUR): does it measure missing flake mass?” in which the validity of approach and the ability of GIUR to predict flake mass reduction is brought into question. state the research questions, give the location and chronology of the archaeological site(s) and samples or the experimental assemblage

Methods and Materials

Hiscock and Clarkson used thirty flakes for their data set. GIUR measurements were made after ten retouch flakes were removed along a margin and retouch was followed by measurement in this manner until each flake was expended. 348 GIUR measurements were taken for the study.

Results

The authors provide a counterargument for the use of GIUR in place of other methods and take argument with the reasoning put forth in the refuted paper. They point out Eren and Sampson’s experiments with GIUR yielded a strong positive correlation (r = 0.91, n = 147) between the measure in question and flake mass lost. Eren and Sampson take issue with the arbitrary measurements and claim that the method employed secured a higher correlation coefficient. Hiscock and Clarkson defend the methodology of their experiment showing that simulations, whether removing multiple (which Eren and Sampson took issue with) or a single flake, yielded very similar correlation coefficients. They state dissimilar designs carried out using GIUR has shown this analysis to be a robust measure. Hiscock and Clarkson also take issue with Eren’s ERP index which they claim must also be dismissed as it yield 0.454 coefficient of determination opposed to 0.778 correlation coefficient for the combination of single and dual margin GIUR in Hiscock and Clarkson’s 2005a study. The authors conclude that Eren and Sampson’s experiment doesn’t weaken the case for the use of GIUR as a robust measure but strengthens it as it yielded a high correlation coefficient. Hiscock and Clarkson employ a conservative approach and implore others ensure the circumstances are optimal when using geometric index of unifacial stone tools reduction (GIUR)

Theoretical and Practical Relevance

This article was an important contribution to the field of lithic analysis because the field covets methods to determine mass loss from retouching. The data yielded from the GIUR method can tell us about tool use of people whose only evidence of existence lay in lithic technology. It is an important work because it gives archaeologist a tool to employ with confidence.