It's amazing the things one finds purely by chance. While looking for something entirely unrelated, I happened upon this article on the Saudi Aramco website explaining the process by which the Middle Eastern world gradually abandoned all use of wheeled transport for the camel. As surprising as it may be to Westerners, the change did happen for eminently sound reasons, and it shows why one has to be careful not to assume that the existence of wheeled transport is some sort of universal marker of "civilization"; where there are more efficient means of transport than horse-drawn wheeled vehicles, or where the requisite draft animals could not be bred (e.g, the entire tsetse fly belt of Africa), it was only natural that the wheel should have made no headway.
It is worth noting in this regard that the tsetse fly remains till this day perhaps the biggest single obstacle to increased agricultural productivity in Africa, as it renders great portions of the continent unsuitable for the cultivation of draft animals, let alone cattle for meat consumption. Only with the emergence of the internal combustion engine has it made sense in tropical Africa to utilize wheeled transport on any scale, and the peoples of the region have since taken to it well enough, proving that it was hardly a concept they were innately incapable of grasping.
Comments