Spearthrower or bow? Hafted projectile points from the Americas refine comparative baselines for tracking projectile technologies

The invention or adoption of bows is one of the most significant global shifts in humanity’s history, and tracking this in the archaeological record depends on metrically distinguishing dart and arrow projectile points. Given the importance of comparative databases in this endeavor, this paper presents an expanded compilation of measurements on 85 hafted points from North America. For South America, we present unpublished data for 22 hafted points and 61 foreshafts. A clear metric gap in point width at 14–15 mm separates arrows and darts. This reflects the weapons' different physical requirements, since these points come from historically independent regions and periods. These patterns are not replicated in ethnographic arrows, which are consistently larger than archaeological arrows. We suggest they not be used in archaeological comparisons. Hafted darts are notably larger than unhafted darts from archaeological sites, which is mostly due to use-life reductions. We suggest that there is no universally applicable data set, nor derived formula or index, that can be used to identify archaeological points as darts or arrows. We recommend nonparametric comparisons focusing on natural breaks in cross-cultural archaeological data.