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On Identifying Stone Tool Production Techniques

On Identifying Stone Tool Production Techniques: An Experimental and Statistical Assessment of Pressure versus Soft Hammer Percussion Flake Form

anthropology-blog-stonesPressure flaking is a stone tool production technique that uses a narrow tool to directly apply force to the edge of a core or tool to detach a flake. Researchers have shown that some of the earliest evidence for pressure flaking comes from South Africa ~75,000 years ago. Other evidence suggests that prehistoric people were pressure flaking in the Upper Paleolithic of Europe around 20,000 years ago, in Siberia by 13,000 years ago, in North America by 12,000 years ago and in Australia 1,200 years ago. This pattern suggests that everywhere that Homo sapiens went they brought pressure flaking with them.

Pressure flaking is an important innovation in human prehistory because it is generally thought to have increased the ability of a flintknapper to make smaller and lighter tools and to trim, straighten, sharpen, and rejuvenate dull tool edges. Pressure flaking also increases the accuracy of flake removal. Identifying pressure flaking in different regions of the globe is important for modeling the causes underlying when and where pressure flaking appears in the record. With this in mind, we designed our experiment to empirically identify pressure flakes in archaeological assemblages.

To do this we designed an experiment to test how well we can distinguish flakes made from the pressure technique from flakes made from soft hammer percussion. For the experiment, we used three nodules of a high-quality chert from Texas. Dr. Eren (Kent State University) conducted the flintknapping for the experiment. He reduced the cores bifacially using soft hammer (antler billet) and pressure flaking (antler tine) techniques. To be included in the analysis, flakes had to have an intact striking platform and fit within a size range. This size range represented the zone in which soft hammer and pressure flakes overlapped. From this overall sample, a total of 560 flakes were analyzed; 392 soft hammer percussion flakes and 168 pressure flakes. From previous studies, we identified 12 variables to measure and record.

We then carried out a several statistical tests, including univariate statistical analyses, statistics on discriminate capabilities, examining shape, and statistics involving size adjusted data. Overall, the results of our analyses demonstrated that pressure flakes, as a group, are shorter, narrower, thicker, and have a higher proportion of bulbs relative to soft hammer percussion flakes. We also showed that pressure flakes can be distinguished from soft hammer percussion flakes with almost 70% accuracy. While our results are consistent with the hypothesis that pressure flakes do indeed possess forms different from soft hammer percussion flakes, we emphasized that these differences are probabilistic in nature and thus should be made on the group or assemblage level to increase the likelihood of identifying the occurrence of pressure flaking. Therefore, we also argued that identification of pressure flaking in the archaeological record must also occur at the assemblage level. Our results offer a quantitative means to distinguish pressure flakes from soft hammer percussion flakes.

This study was published in American Antiquity by Briggs Buchanan, Veronica Mraz, and Metin I. Eren

Dr. Buchanan is an Assistant Professor at the University of Tulsa, Ms. Mraz is a Doctoral Candidate at the University of Tulsa, and Dr. Eren is an Assistant Professor at Kent State University. Funding for this research was provided by QUEST Archaeological Research Program (M.E.) and through the University of Tulsa’s Odell Summer Research Grant (V.M.).