Wheel

by Anthony Barbieri-Low
I. Introduction--Wheeled Transport around the World
The invention of the wheel for transportation of humans and their cargo was one of the greatest inventions of the ancient world. 1What makes the invention of wheeled transportation most striking is its novelty. Wheeled motion is the only form of movement which does not have a counterpart in the wild kingdom. There are animals which fly, swim, walk, slither, and hop, but there are none yet discovered which roll. Overcoming the resistance of friction and gravity, man's invention of the wheeled vehicle allowed him to multiply his productivity immeasurably, enabling a level of complexity and mobility in his societies which had formerly not been possible. It also gave him a frighteningly fast conveyance to use in brutal warfare against rival groups and an unmistakable marker of status to laud over those less fortunate. Therefore, it is not surprising that the wheeled vehicle made its first appearance in the early states at about the same time that early forms of writing and metallurgy were being systematized and refined to levels which enabled the rulers to administer and coerce large populations. Even though man had excellent tools and wood-working skills throughout the earlier Paleolithic and Neolithic periods, he never had occasion to invent the wheeled vehicle until the complexity of his society established the groundwork for its introduction.
However, the invention of wheeled vehicles is not an inevitable consequence of social complexity. There are other very important practical factors to consider. According to Stuart Piggott, the introduction of wheeled vehicles carries three prerequisites: 1) adequate domesticated draught animals 2) sophisticated wood carpentry skills such as joinery and heat bending 3) adequate timber resources. 2To these I would add the fourth requirement of amenable terrain. Without all four of these requirements in place, a society, no matter how complex, would not be able to use a technology of wheeled vehicles.
For an example of the binding nature of these requirements, consider the case of the New World, where wheeled vehicles were never used for transportation before the Conquest. Yet, surprisingly, there are dozens of wheeled "toys" dating froma.d.400 which prove that Mesoamericans knew how to make objects roll on wheels 3(see fig. 1). These clay toys, whose function is uncertain, represent various animals or deities. Axles holding clay wheels travel through their front and rear feet. Why would societies as complex, aggressive, and skillful as those which arose in Mesoamerica, produce such toys yet choose not to exploit this technology in transportation or warfare? The answer lies in the fact that no suitable draught animals existed in the New World which could have pulled large vehicles. Neither equids nor bovids were present in the New World at this time, and available animals such as the llama or the dog simply could never provide adequate traction. 4
Before turning to the case of the structure and function of the earliest Chinese wheeled vehicles, it is necessary to review briefly the history of wheeled vehicles in the other great centers of civilization in the Old World, namely the Near East, Europe, and the Indus River Valley.