Testing and reconsidering atlatl dart ballistics: Implications for recent theories on social organization and change

• The atlatl and dart weapon is characterized by variability in form and application. • Heavier darts carry less velocity but substantially more energy, predicted by the force-velocity relationship in throwing. • Atlatlist height and weight tends to correlate with greater dart energy and velocity. • Both sex and experience impact kinetic energy but are overridden by variability between individuals. • Research that stereotypes weapons and overlooks weapon and user variability is prone to error. The atlatl and dart is characterized by a significant degree of variability in form, application, user physique and performance. Archaeologists sometimes overlook variability when theorizing about advances in weapon technology, social implications of weapon change, and the processes that produce the archaeological record, but this “stereotyping” of technology comes with a cost. Here we use multivariate procedures on a large dataset to examine the interactions of many variables in atlatl dart launching. Our models demonstrate that heavier darts tend to result in lower velocity but significantly higher kinetic energy, but also that marked differences occur in the KE achieved by individual atlatlists—more people can effectively use lighter darts, which other experiments show are effective against a range of small to medium prey, while the strongest throwers can achieve the highest KE using heavier darts, arguably more effective against larger prey. Atlatlist experience plays a less significant role than overall strength, and some new throwers achieved high velocities with little practice. Weapon and user variability complicates some recent ideas about social change and weapon function. Future research on this topic should focus on understanding variability by modeling atlatl launching biomechanics and testing a broader sample of users and equipment.