The propulsion phase of spear-throwers and its implications for understanding prehistoric weaponry

Understanding the appearance and evolution of prehistoric weaponry is a key topic in archaeological research. While stone or osseous projectile points are identified archaeologically based on damage patterns and other wear traces, identifying how these weapons were propelled requires a more thorough understanding of the ballistic behaviour of each weapon system. Even if the spear-thrower and dart is a commonly known weapon system that is often used in projectile experiments, its functioning is still not yet fully understood. In this article, we contribute to its understanding with a detailed analysis of the propulsion phase of the dart. We use high-speed video recordings and show that the propulsion of a dart has a complexity that goes beyond a simple lever effect or an arm extender provided by the spear-thrower. We argue that the focus should not only lie on the rotation of the spear-thrower but also on the displacement of the spear-thrower hook and the dart’s butt during the entire propulsion phase. We demonstrate that the gestures of the user and the specific characteristics of both the spear-thrower and the dart represent three inseparable elements that determine a dart’s flight and its ballistic behaviour. Knowledge on the propulsion phase of the dart is therefore a prerequisite for insights into the impact phenomenon, for an adequate understanding of impact fractures on projectile points, and for the recognition of weapon propulsion modes on an archaeological level.