Les gestes retrouves: a 3D visualisation approach to the functional study of Early Upper Palaeolithic grinding stones

Sorin Hermon, Laura Longo, Dante Abate, Giusi Sorrentino, Natalia Skakun


Les gestes retrouves: a 3D visualisation approach to the functional study of Early Upper Palaeolithic grinding stones

The paper will present an innovative approach to the identification and characterization of use-wear traces on Aurignacian grinding stones used to processed plant in order to get staple food. Such a study is essential in reconstructing ancient dietary habits of humans at a crucial stage of human colonization in Eurasia. The current study focuses on the potential contribution of 3D investigation, at various levels of detail and resolution, to the identification of such traces and residues. The working methodology is still under revision, but it includes the following steps, firstly applied on a grinding stone from the Upper Palaeolithic site of Surein, Crimean Peninsula:

1. An overall documentation of the grinding stone: 3D geometry and rectified macro-photography.
2. Rugosity analysis of the stone’s surface, in order to identify anomalies relatable to human intentional intervention (grinding). This analysis is performed using two approaches: cloud compare and Meshlab filter functions of colorizing curvatures (several tests are currently performed, using different curvature types).
3. 3D documentation of molds taken in selected areas on the active surface of the grinding stone. These were 3D scanned using a shuttered light scanner and photogrammetry. Values had to be inversed along the Z axis, in order to correctly represent the surface micro-topography.
4. Rectified digital images taken with a digital microscope at various magnifications, at logarithmic steps from x25 to x2500. These were assembled together in a CAD system, each magnification being considered one layer, in order to create a mosaicking of the surface.
5. Measurements of the area of trace marks and characterization of their shape. Clustering of these marks along the working surface of the stone and associated starches.

Overall, more than 40 trace marks were observed and characterized. The rugosity analysis of the working surface of the grinding stone correctly identified areas that have been modified by intentional human intervention. The presence of wear-traces and adhering starches, identified under microscope, along with morphological characteristic of use marks, are among the earliest evidences for plant processing at the dawn of modern humans in Eurasia. Currently, other 10 stones related to plant grinding (both grinding stones and pestles) are under analysis, with very promising preliminary results. The integration of 3D documentation, macro-photography and digital microscopy provided an ideal set of 3D and 2D data that has been successfully used for the functional analysis of Aurigancian grinding stones.