Judith Charlin

Relative importance of modularity and other morphological attributes on different types of lithic point weapons: assessing functional variations.

The specific using of different prehistoric weapons is mainly determined by its physical properties, which provide a relative advantage or disadvantage to perform a given, particular function. Since these physical properties are integrated to accomplish that function, examining design variables and their pattern of integration or modularity is of interest to estimate the past function of a point. Here we analyze a composite sample of lithic points from southern Patagonia likely formed by arrows, thrown spears and hand-held points to test if they can be viewed as a two-module system formed by the blade and the stem, and to evaluate the degree in which shape, size, asymmetry, blade: stem length ratio, and tip angle explain the observed variance and differentiation among points supposedly aimed to accomplish different functions. To do so we performed a geometric morphometric analysis on 118 lithic points, departing from 24 two-dimensional landmark and semi landmarks placed on the points contour. Klingenbergs covariational modularity tests were used to evaluate different modularity hypotheses, and a composite PCA including shape, size, asymmetry, blade: stem length ratio, and tip angle was used to estimate the importance of each attribute to explaining variation patterns. Results show that the blade and the stem can be seen as “near decomposable units” in the points integrating the studied sample. However, this modular pattern changes after removing the effects of reduction. Indeed, a resharpened point tends to show a tip/rest of the point modular pattern. The composite PCA analyses evidenced three different patterns of morphometric attributes compatible with arrows, thrown spears, and hand-held tools. Interestingly, when analyzed independently, these groups show differences in their modular organization. Our results indicate that stone tools can be approached as flexible designs, characterized by a composite set of interacting morphometric attributes, and evolving on a modular way.

Morphological Diversification of Stemmed Projectile Points of Patagonia (Southernmost South America). Assessing Spatial Patterns by Means of Phylogenies and Comparative Methods

The aim of this work is to model patterns of morphological variation in Middle-Late Holocene stemmed projectile points from Patagonia through comparative methods. With this purpose, we explore the potential of different analytical strategies using projectile point shapes, obtained by means of geometric morphometrics. Phylogenetic and spatial variations were used to model morphological patterns on different scales. Morphological data comes from digitized images of projectile points from different areas of Patagonia. Morphometric characters were obtained using landmark and semilandmark descriptors. Mean shape by area was computed and used in cladistic analysis to model diversification trends. Then, phylogenetic and geographical coordinates were estimated for each data set and used as predictor variables in multiple regression procedures. Results suggest that historical patterns of shape change are channeled by spatial dimension. Pattern of mobility and interaction among human populations in Patagonia in the Middle-Late Holocene are discussed in light of these results.

Disponibilidad de materias primas líticas en la Costa Nororiental del Estrecho de Magallanes (Chile): Una aproximación exploratoria

Lithic raw materials availability in the northeastern coast of the strait of Magellan (Magellan, Chile) is characterized by means of nine rock samples collected between Posesion and Laredo bays following Franco and Borrero’s (1999) sampling methodology. Abundance, richness, flintknapping quality and size of rocks in coastal deposits are described. Thin section microscopic determinations allowed us to identify several types of lithic raw materials, especially of fine-grained dark rocks, which are different to those usually present in the Pali Aike volcanic field. These new data are discussed in relationship with the glaciological and archaeological information

Nuevos Sitios con Representaciones Rupestres en la Localidad Potrok Aike (Santa Cruz, Argentina)

New data about rock art distribution in Potrok Aike locality (Santa Cruz Province, Argentina) is presented. Motif concentrations and isolated motifs were surveyed on volcanic outcrops located to the northwest of the Potrok Aike lagoon. They are paintings, mainly in red, with a few motifs in white. Most of them are abstract representations, although hand stencils are the second in abundance. Different tonalities (two red tones), superposition and repainting suggest distinct times of painting execution, which according to the regional background correspond to Late Holocene. Shape, size, color and tonality, technical treatment and motifs distribution are described. Finally, a regional comparison shows the main trends in Pali Aike volcanic field rock art.