Simulating Shape Variation in Material Culture: The Simumorph R-package

Abstract

Abstract Archaeologists have devoted a significant amount of effort to define their types, or units of analysis. However, strong disagreements persist even after years of debate. This may occur for many reasons, some intrinsic to the archaeological record itself—since different technocomplexes may involve distinct and not always comparable types—and others related to the discipline’s epistemology, where interobserver bias and differences in theoretical schools and training traditions can play a key role. As a result, most archaeological analyses, usually based on type presence/absence or type frequencies, present uncertainty levels from the start, which are not always due to the archaeological record itself, but to how we analyse that record. In this work, we adopt a materialist view to present an alternative approach where we analyse purely artefact shape without the need for previous categorisation. To do this, we resort to Geometric Morphometrics, widely used in archaeology, and we develop a simulation framework for stepwise artefactual change. We provide the software tools to do this, which have been compiled in the R-package Simumorph, and we showcase its performance in four simulated archaeological scenarios. Here, we base our simulations on the geometric microliths found during the Early and Middle Holocene in the Western Mediterranean, but the framework can be applied to any context where shape variation matters.