shoulder joint in humans is not a snug ball and socket, as in our hips, but a more loose and open arrangement. This allows the shoulder to be limber and to rotate freely—exactly what’s needed for forceful throwing—but it also means that we dislocate our shoulders easily. We throw with our whole bodies. Try throwing an object forcefully while standing still and you can hardly do it. A good throw involves a forward step, a brisk rotation of waist and torso, a long backward stretch of the arm at the shoulder, and a powerful hurl. When executed well, a human can throw an object with considerable
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