Levers, not springs: How a spearthrower works and why it matters

Abstract

A spearthrower, or atlatl, works as a lever to propel a light spear or dart, but there are still alternative theories about the mechanical principles. Howard proposed that atlatls work by extending the time force can be applied to a spear. Others suggest that the flex of the atlatl or the dart, or both, stores energy to propel the dart as from a spring. Both of these theories can be demonstrated to be wrong by a variety of evidence, including slow motion images. Those who believe that spearthrowers work by spring power often see them as ancestral to bows. Because they work by different principles, this is highly unlikely. Understanding how a spearthrower works is important in examining its capabilities and place in the evolution of technology, and both practical experimentation and theoretical understanding are necessary.