A spear-thrower, used to hunt mammoths, consists of a shaft with a spur at the end that supports and propels the butt of the dart, that is thrown by the action of the upper arm and wrist.
The throwing arm acts as a lever, and the spear-thrower increases the length of the lever, that in turn allows that the thrower increases the acceleration of the dart.
Innovation in spear-throwers design included improvements such as elements to fit the fingers, the use of flexible shafts and thinner darts for added power and range. An important improvement was the introduction of a small weight strapped to its midsection. The stone weight adds mass to the shaft of the device resulting in a more forceful and accurate launch of the dart.