Does the shape make a difference? Evaluating the ethnic role of cranial modification in the Pampa-Patagonia region (Argentina) during the late Holocene

The Pampa-Patagonia region in Argentina has been characterized as an ethnically complex territory during the late Holocene. This region presents a high frequency of human burials and, although several papers have focused on the study of cranial vault modification, none of them have discussed systematically the ethnic role of this practice. In this study, we assess the role of cranial modification as a potential expression of ethnic identity among hunter-gatherer groups from northeastern Patagonia and southeastern Pampas during the late Holocene. In order to define morphological groups and to recognize spatio-temporal patterns, we applied 2D landmark-based morphometric methods and multivariate statistical techniques on 216 adult male and female crania, which were grouped into three geographic units. The results of this paper do not support the idea of cranial modification as an ethnic marker within the region, as the different modifications follow a temporal sequence and are present in the entire study area. Also, our results show that the groups of cranial modification are different from each other, and they show variability among the geographic units. The reasons behind the change between cranial modification groups remain unclear, but it coincides approximately with some technological and symbolic changes in the material record. Variability within groups is understood as the result of a non-standardized practice and the existence of local ways of doing among the hunter-gatherer of the study region. As we see in shared art motives and decorative patterns, cranial modification would have represented another correlate of a macro-regional visual communication system that worked during the late Holocene in Pampa-Patagonia.