The history of the automobile is the history of transportation in general. It is the story of the development of mobility options. In ancient times, humans were solely reliant on the strength and endurance of their legs; as far as they could walk, that was their domain, and as far as they could go, the environment was open to them for their sustenance. However, the human body was not well-suited for rapid and enduring walking or running. With the acquisition of upright walking, humans lost a valuable trait that animals still possessed. They suddenly stood with their broad side facing forward, while in animals, the axis of movement runs through the narrow side, resulting in generally streamlined cross-sections that offer minimal resistance. Similarly, the development of the hand from the clawed foot, the transformation of human teeth from those of a predator, and much more signify this evolution.