Cultural transmission and correlational selection in Late Period projectile points from the Puna of Salta, Argentina (CE 900 - 1500)

This work proposes a methodology for documenting metric patterns of variation and trait correlation in Late Period (ca. CE 900-1500) projectile points from the Puna and pre-Puna of Salta, Argentina. In so doing, our main goal is to explain the patterns observed in terms of mechanisms of cultural evolution and selection over the design of the artefacts. We applied this methodology to assemblages of concave-based triangular projectile points from four archaeological sites whose chronologies are well established. As a result, we were able to document low degrees of variation, as well as high, positive, significant, Pearson co-variation and partial correlation coefficients between metrical traits. These results suggest a process of correlational selection that preserved an artefact design with a structure of highly integrated traits that maximised the edge-area in relation to the haft, turning these projectile points into very lethal weapons, even for potential use in interpersonal violence. This lends support to the hypothesis presented here, where replication of these projectile points occurred within a process of stabilizing cultural selection through biased transmission mechanisms that maintained the functional relations between the variables at the design scale, which in turn favoured the selection of artefacts suitable for effective weapons in a context where hunting was a strategy that optimized animal biomass acquisition, enhancing domestic herd viability.