Of the five metacarpal bones that form the framework of the hand, the thumb metacarpal forms the most freely movable joint with the carpals. This is extremely important; if not for this fact, humans would not have the range of movement possible between the thumb metacarpal and the trapezium (for example, our ability to oppose the thumb to the fingers). This greater dexterity is what sets humans apart from and other animal, thus allowing us to rule the world because of our greater environment-manipulation skills.