A geometric morphometric assessment of plan shape in bone and stone acheulean bifaces from the Middle Pleistocene site of Castel di Guido, Latium, Italy

Abstract

Flaked bone artifacts are a noteworthy component of some Early and Middle Paleolithic tool kits. Several Paleolithic sites with lithic assemblages attributable to the Acheulean Industrial Complex (Mode 2) have yielded bifacial bone artifacts. Many of these bone implements are similar to classic handaxes in plan shape. The arbitrary imposition of form represented by these bone bifaces suggests the deliberate application of certain operational concepts that originate from particular Acheulean technological behaviors, namely, stone handaxe manufacture. In addition, the presence of these bone tools suggests an application of specific reductive techniques that originated in both Mode 1 (i.e., Oldowan) and Mode 2 (i.e., Acheulean) lithic technologies. How does the Acheulean model for stone biface shape compare to that observed for bone biface shape? In order to understand the degree to which Acheulean stone bifaces may have served as a model of form in flaked bone technology, an objective method for evaluating form is necessary. The dimensionless approach of geometric morphometrics was applied to the study of 2D bone and stone biface plan shape. The similarity of bone and stone bifaces from the Middle Pleistocene (∼300 kya) Acheulean site Castel di Guido, Latium, Italy was evaluated by a geometric morphometric analysis of 2D outlines. The null hypothesis that there is no difference in the 2D shape of each artifact material class was tested by principal component analysis (PCA) and MANOVA/CVA of eigenshape scores. Results of the analysis show no significant difference between the plan morphology of bone and stone bifaces. These results may indicate that Acheulean concepts of preferred 2D shape were applied in the production of some bifacial bone tools and that a great disparity in raw materials did not significantly influence 2D biface morphology. Furthermore, these results lend support to the idea that Mode 2 stone flaking techniques and tool types were directly applied to bone materials in some instances. © 2010 Springer-Verlag New York.