An investigation of the flake-based lithic tool morphology using 3D geometric morphometrics: A case study from the Mirak Paleolithic Site, Iran

Abstract

Today archaeologists are increasingly seeking more objective methods for analyzing archaeological remains to obtain the most reliable results possible. To achieve this goal, methods developed in other disciplines are being introduced gradually into archaeology and their effectiveness is being tested; this is particularly the case for archaeological analysis of lithic artifacts. One such method, borrowed from evolutionary biology that has become increasingly widespread in stone tool archaeology is geometric morphometrics. This method can be used to generate information regarding inter- and intra-assemblage morphological variability in lithic artifacts and to inspect the mechanisms and causes driving this variation. In this paper, 3D landmark-based geometric morphometrics is used to study diachronic changes in the morphology of lithic tools. This study concerns an assemblage of flaked lithic tools from the open-air Paleolithic site of Mirak, located along the northern fringe of the Iranian Central Desert. These lithics belong to two archaeological layers. Layer 2, which features a combination of Middle and Upper Paleolithic lithic materials (ca. 33–26 kya), and Layer 3, which consists mainly of late Middle Paleolithic materials (ca. 55–43 kya). These layers belong to Marine Isotope Stage 3, a time of rapid fluctuation in climatic and environmental conditions at the global and regional scales. The aim here is to investigate whether there are any significant morphological differences between the two sets of aforementioned lithic assemblages, and subsequently, to suggest possible causes of the stability or variability in this morphology. The results of the analysis indicate that the general morphology of the flake-based lithic tools is not significantly different between the two layers. To inspect the rationale for such diachronic stability, the morphology of the original lithic raw materials and population dynamics are studied. It seems that at least part of the answer lies in the flow of information and cultural transmission related to the presence of metapopulations in the Iranian Central Plateau during Marine Isotope Stage 3.