Identifying Major Transitions in the Evolution of Lithic Cutting Edge Production Rates

Abstract

The notion that the evolution of core reduction strategies involved increasing efficiency in cutting edge production is prevalent in narratives of hominin technological evolution. Yet a number of studies comparing two different knapping technologies have found no significant differences in edge production. Using digital analysis methods we present an investigation of raw material efficiency in eight core technologies broadly representative of the long-term evolution of lithic technology. These are bipolar, multiplatform, discoidal, biface, Levallois, prismatic blade, punch blade and pressure blade production. Raw material efficiency is assessed by the ratio of cutting edge length to original core mass. We also examine which flake attributes contribute to maximising raw material efficiency, as well as compare the difference between expert and intermediate knappers in terms of cutting edge produced per gram of core. We identify a gradual increase in raw material efficiency over the broad sweep of lithic technological evolution. The results indicate that the most significant transition in efficiency likely took place with the introduction of small foliate biface, Levallois and prismatic blade knapping, all introduced in the Middle Stone Age / Middle Palaeolithic among early Homo sapiens and Neanderthals. This suggests that no difference in raw material efficiency existed between these species. With prismatic blade technology securely dated to the Middle Palaeolithic, by including the more recent punch and pressure blade technology our results dispel the notion that the transition to the Upper Palaeolithic was accompanied by an increase in efficiency. However, further increases in cutting edge efficiency are evident, with pressure blades possessing the highest efficiency in this study, indicating that late/epi-Palaeolithic and Neolithic blade technologies further increased efficiency.

Fig 1. Demonstration of the method used to measure cutting edge length, showing a photograph of an original blank (a), and two stages in the process of reducing the photograph to a measurable polygon (b and c).

Note the platform is excluded in the polygon measurement so as to measure possible cutting edge only.

Fig 2. Bar chart, with one standard error bars and each data point superimposed, showing the cutting edge per gram values for each repetition of bipolar (N = 3; μ = 10.36), multiplatform (N = 7; μ = 16.90), discoidal (N = 7; μ = 17.69), biface (N = 7; μ = 19.39), Levallois (N = 7; μ = 21.83), prismatic blade (N = 7; μ = 22.46), punch blade (N = 3; μ = 22.95) and pressure blade (N = 3; μ = 25.49) knapping.

Open circles represent the results from the intermediate knapper and closed circles represent the expert knapper.

Fig 3. Bar chart, with one standard error bars and each data point superimposed, of the eight technologies grouped into their corresponding time periods, showing the Oldowan, consisting of bipolar, multiplatform and discoidal technologies (N = 17; μ = 16.07), the Middle Palaeolithic, consisting of biface, Levallois and prismatic blade technologies (N = 21; μ = 21.23), and the Upper Palaeolithic and onwards, consisting of punch blade and pressure blade (N = 6; μ = 24.22).

Open circles represent the results from the intermediate knapper and closed circles represent the expert knapper.

Fig 4. Scatter plots with both axes transformed using the natural log (ln) examining the influence of mass, thickness, bulb thickness, length, width, elongation, platform depth, platform width and exterior platform angle (EPA) on the cutting edge length per gram of core for individual flakes.

The sample size of each scatter plot is 488, except for the platform depth, platform width and EPA scatter plots, which had sample sizes of 460 owing to the presence of some crushed platforms.

Fig 5. Boxplots of qualitative variables.

Platform type plot (a) compares dihedral (N = 178; Mdn = 25.99), plain (N = 182; Mdn = 30.52) and focalised (N = 100; Mdn = 65.81) platforms. Termination type plot (b) compares plunging (N = 22; Mdn = 17.45), step or hinge (N = 58; Mdn = 23.02) and feather (N = 408; Mdn = 36.45) terminations. Platform preparation plot (c) compares no preparation (N = 105; Mdn = 19.49), either overhang or faceting (N = 202; Mdn = 26.44) and both overhang and faceting (N = 181; Mdn = 44.67).