LAUSR

Originally developed for the quantitative analysis of organismal shapes, both two‐dimensional (2D) and 3D geometric morphometric methods (GMMs) have recently gained some prominence in archaeology for the analysis of stone tools—unquestionably the primary deep‐time data source for the earliest periods of human cultural evolution. The key strength of GMM rests in its ability to statistically quantify and hence qualify complex shapes, which in turn can be used to infer social interaction, function, reduction, as well as to assess classification systems and cultural relatedness. The methodological diversification that has accompanied the rise in popularity of this particular suite of methods has, however, also resulted in an increasing lack of comparability and interoperability, which—ironically—works against the promise of GMM to provide a tool for comparing artifact shapes that is not sensitive to interanalyst variation. Standardized protocols, vetted datasets, as well as case‐ transferable and fully reproducible methods do not currently exist, hampering the full utility of geometric morphometrics as an approach to comparatively understand human behavior as reflected in these lithic proxies. Additionally, the emerging issue of methodological diversity in the geometric morphometric analysis of stone tools is further compounded by issues related to landmark selection. When applied to organisms, landmark selection is guided by a priori knowledge about ontogeny, homology, and function. For stone tools, however, only very few such evident landmarks suggest themselves. Instead, many studies have used landmarks selected specifically to highlight particular design features of a given tool class (e.g., stemmed points or leaf points). These cannot, however, be easily compared across tool classes. Other studies have used sets of equidistant landmarks measured perpendicularly from a given tool's longest axis to its margins to describe overall shape. In this context, whole‐outline geometric morphometrics offers an alternative approach that circumvents landmark selection by describing the entire outline of the recorded artifact. It is computationally tractable, readily replicable, and well‐suited for 2D object representations such as drawings and photographs, many of which exist in excavation reports, catalogs, finds registers and the published literature at large. Furthermore, emerging approaches in paleobiology now allow such continuous shape data to be used in phylogenetic applications, opening up the possibility of effectively combining stone tool geometric morphometrics with cultural phylogenetics in one workflow.