Projectile point morphology and penetration performance

Prehistoric pointed lithic armatures (used to tip spears, darts, and arrows) vary considerably in mechanically-relevant aspects of their morphology, such as tip cross-sectional shape, cross-sectional perimeter, and cross-sectional area, mechanical advantage, and edge sharpness. The effect of variation in these parameters on penetration performance and lethality, however, is poorly understood. Six 3D-printed points that varied in cross-sectional shape, tip cross-sectional area, tip cross-sectional perimeter, mechanical advantage, and edge sharpness were fired into ballistic gelatin under controlled conditions to evaluate the importance of these variables on point performance. Tip cross-sectional perimeter was found to have the greatest effect on penetration depth in the gelatin, and mechanical advantage was also significantly related to penetration. Cross-sectional shape and tip cross-sectional area were not significantly related to penetration depth, while edge sharpness inversely affected penetration. These results highlight the importance of tip cross-sectional perimeter in the evolution of projectile point design (and reinforce its utility as an indicator of long-range projectile weaponry in the archeological record), but also underscore the multiple constraints that interact when trying to design points to maximize penetration performance, lethality, and durability.

Duke Scholars

Author Steven E. Churchill Evolutionary Anthropology