The ontogeny of throwing and striking

Humans are the most adept throwers in the animal kingdom. Although throwing has been recorded in other primates, it is rare, weak, inaccurate and entails only arm movement. In contrast, human throwing is an explosive act employed from a bipedal stance that involves a complex, exceedingly rapid, full-body movement. This motion generates a pulse of kinetic energy in the legs that is progressively augmented by the pelvis, trunk, arm and hand, where it is transferred to a missile that is launched toward the target with high velocity and accuracy. Linking the study of throwing development in young children with analysis of the adult throwing motion makes it possible to address the question of whether human throwing is an acquired behavior or is based primarily on an inherited motor program. Current evidence supports the conclusion that the role of instruction and learning is minimal. Human throwing is predominantly the result of an innate motor program which emerges at a very early age in all children without teaching, yields a throwing motion that is the forerunner of the one used by adult athletes, is characterized by a prominent gender difference, and proceeds in some adults to a high level of proficiency. The same conclusions apparently apply also to striking (club-swinging), which employs a similar full-body motion. An explanation for these observations is presented, based upon the concept that throwing and club-swinging prowess provided reproductive advantages during early human evolution.