Life history or stylistic variation? A geometric morphometric method for evaluation of Fishtail point variability

Abstract

Fishtail points are considered an indicator of the presence for one of the earliest and most successful human adaptations during the late Pleistocene in South America (~12,900–12,200 cal BP). Although these points display a wide range of variability both in size and shape, previous studies are mainly technological and descriptive observations. No efforts have been made to propose qualitative and quantitative indexes in order to understand how the rejuvenation/resharpening process may have affected the observed variability. In this paper, we explore different analytical methods to understand the rejuvenation process, explain the morphological variability of the Fishtail points and evaluate them from the perspectives of geometric morphometrics and multivariate statistics. This analysis allows us to generate new fresh interpretations and ideas about the rejuvenation of points. The combination of 2d geometric morphometrics, linear measurements, and multivariate regression, supports the hypothesis that the continuum of shape variation is explained by the long life history trajectories of the Fishtail points.