Mankind’s ingenuity is so often undermined by Nature. For example, our chemists spend decades trying to perfect vaccines for illnesses only to discover the same chemical compounds already exists in some hitherto unknown Amazonian plant. Nature, though, can’t always upstage us. Take the wheel for example. When humans invented it 5000 years ago, it never previously existed in Nature. Well, that’s what we always thought.
The Wheel: Origins
Our early ancestors probably made the first wheels from tree trunks simply because they were common and rolled easily. Round or nearly round rocks may have been tried too, but rocks are heavier and far more difficult to work with than wood.
The Potter’s Wheel
Surprisingly, the earliest use of the wheel was not in transportation, but in pottery – the potter’s wheel – and a tree-trunk cross-section probably served that purpose. That was over five thousand years ago. It took many more years for wheels to be used in transport because most of the landscape of the time was too rough.
When eventually relatively flat paths developed, tree trunks and logs were used in groups to help move heavy objects – the log at the back manhandled to the front as the load trundled along. This soon led to the development of a flatbed platform that could accommodate objects of different shapes and sizes – the platform carrying the objects would roll on the logs. A refinement of that system was to use a single log and to put runners under the platform turning it into a sort of sled. This made moving it easier since only the thin runners were in contact with the rolling log, causing much less abrasive resistance than if the platform was sitting directly on the log.
The sled-like device led directly to the development of wheels and axles. With constant use, the two runners of the sled wore two deep grooves into the rolling log. This made the whole contraption more stable and led to a much more significant development. People operating the sled noticed that it was easier to move an older sled, whose roller log had deep grooves in it, than a new one that had none. The reason was simple: though a sled moved the same distance with each revolution of the log regardless of the age of the log, the runners sitting on the old log had significantly less resistance. This was because the log had been worn thinner at the point of contact, so the circumference of the part of the log they rubbed against was shorter.
The Wheel And Axle
Though the grooves made movement much easier, it was still awkward to maneuver a thick heavy log laden with goods over rough terrain. Our ancestors soon realized that only the extremities of the roller needed to be thick and that it would be much easier to maneuver the whole sledge if the part of the roller between the two grooves was much thinner. So they chipped away most of the center part of the roller creating a primitive axle with wheels at either end. It was a small step from that design to one where the axle and wheels were separate parts with the axle held rigidly in place under the sled and its ends slotted into a hole in each wheel.
These early wheels made from relatively thin slices of tree trunks were not very strong, however, and it wasn’t long before they were replaced by wheels made from boards with rounded ends.
Did Mankind Really Invent The Wheel?
For millennia, the wheel was man’s most important invention and was one invention he didn’t copy from Nature: No animal has wheels instead of feet, nor circular cogs to move its limbs; no part of any animal or human naturally rotates continuously. In short, with the wheel, man was a step ahead of Nature. At least, that’s what he believed until recently.
Unknown to Bronze Age man, Nature had invented the wheel eons before the first man walked on the earth. In fact, the ground he eventually walked on was teeming with microscopic creatures propelled by wheel-like mechanisms. The soil bacterium rhizobium – common then and now – is one such organism. It uses a spinning flagellum propeller attached to a shaft that rotates freely and continuously in a hole in the cell wall – a wheel with an axle, if ever there was one. In his book The Ancestor’s Tale, evolutionary biologist Richard Dawkins suggests that these wheels may even have been the Earth’s first locomotion devices since bacteria have existed here for billions of years.
Sorry, Bronze Age man, Nature got there first. To be fair to you, though, you didn’t copy Nature; you came up with the wheel quite independently and, whatever way we look at it, it was a pretty smart idea. The old maxim says that there’s no point in reinventing the wheel. Thank goodness you ignored it!