ABSTRACT
For almost all of human history, transportation of ourselves, our belongings, or other cargo has depended either on the use of human muscles or on the muscles of certain animals (horses, camels, oxen, and occasionally more exotic animals such as elephants). From the dawn of early hominids several million years ago, the obvious form of “transportation” was to use the energy of our own bodies for walking or running. We can also carry or pull things. Photographs of some of the primitive peoples of the world show them carrying animal carcasses or other burdens slung from a pole carried along by two or more people (as in Figure 17.1).
