The Wheel: 6,000 Years of Rolling Along

There are a few inventions humans have come up with that literally changed our behavior patterns. Probably the first two that come to mind are agriculture and language. We must eat and we must communicate. For thousands of years early humans were nomadic hunter-gatherers. Then, when we learned how to cultivate crops, the advent of agriculture led to the establishment of sedentary communities and governments. Of course, the ability to communicate through words or hand signs has proven fundamental to the well-being of all human societies, even many animal groups. Many species of animals have a rudimentary form of communication from tweets to barks, to purrs, to growls, to the songs of whales. But the human ability to write down our thoughts takes the use of language far beyond what any animal is capable of. Spoken language has been a part of human society so long we can only speculate as to when and where it originated.

Another major invention that is so much a part of our daily activities that we take it for granted is the wheel. It is a wholly human invention. Although some animals make use of sticks or rocks to acquire food or build shelters, none of them come close to using a wheel for any purpose, especially transportation.

Well, perhaps it could be argued that dung beetles have evolved to figure out that round things roll and can be pushed. They roll gobs of animal feces into little spheres that they push along with their hind feet to their burrows. But even a ball of dung cannot really be described as a wheel. Wheels are round but not round all over. However, could it have been that humanity’s first wheel was invented by some innovative neolithic person watching a dung beetle rolling a ball of dung and was inspired to attach two round pieces of wood connected by a stick to a box made of interwoven twigs? Sometimes major inventions come from little inspirations. We’ll call this the dung-ball-to-wheel hypothesis.

Another possible inspiration for the wheel might have been when thousands of years ago someone sat on a log and it rolled out from under him or her carrying the person a few feet down a hill. The person realized that a rolling log could be used to transport a load when something was rolled over it. It is believed that rolling large stones on a sled over a series of logs is how the builders of Bru na Boinne in Ireland, Stonehenge in England, the Egyptian pyramids and other groups who built large, heavy structures moved the heavy stones from quarries to the building sites.

Dozens or hundreds of people pulling a sled over rolling logs was a slow and dangerous way to transport stones that weighed thousands of pounds and were far too heavy to be carried. Yet, it was probably this system that led to the wheel and axle idea.

Although today we think of the wheel as having been around for many thousands of years, compared to other human innovations, such as the use of fire, language, agriculture, sewing, building boats, clay pottery, and even smelting copper, a technology which dates back almost 9,000 years, at around 5,500 to 6,000 years old, the wheel is relatively young. For most of our history we carried our loads on our backs or pulled them on sleds over logs. Perhaps thousands of years ago someone had thought of putting slices of logs on the sides of a sled, but it seems that part of the problem was that not until the late Neolithic Age, did we have the tools needed to make wooden wheels and axles that fit together precisely.

Most historians attribute the first wheels to the Sumerians who built a civilization in the area we now call Mesopotamia between the Tigris and Euphrates Rivers in today’s Iraq. It seems that around 6,000 years ago the first wheels were used as potters’ wheels before someone thought of putting two of them on a sled with an axle holding them upright. But once that was done, the idea caught on quickly. By around 5,500 years ago wheels were being used extensively not only in the Middle East, but in what is now Europe and Asia, especially in places that had domesticated horses.

Since the earliest wheels were made of wood, very few remnants of them have been found. One of the earliest found so far was a solid wood wheel discovered in a marsh near Ljubljana, Slovenia in 2002. It was dated at about 5,100 to 5,500 years old and was apparently used on a pushcart.

It was around 6,500 years ago we began to make use of the horse as a beast of burden or to pull a plow rather than as just a source of food and hide. Then when the wheel came along, it was discovered that horses were excellent at pulling wheeled carts. Humans made horses and wheels inseparable companions. It was around 6,000 years ago that we learned how to ride horses and for many centuries, either ridden or pulling wheels vehicles, horses became humanity’s primary mode of transportation.

At first, the wheels and axle were fastened together with the axle being held on to a cart by slotted pieces of wood. But soon it was discovered that carts could turn corners better if each wheel turned independently at different speeds. So, the axle became fixed and the rotating wheels were held on to the axle by a wooden pin run through the end of the axle. Later came a metal threaded thimble fitted over the axle. When the wheel was put on it could be secured by a large nut screwed onto the axle thimble.

Different regions developed different innovations to the wheel. The Greeks, for example, made wheels out of cut pieces of wood instead of one solid piece. Anatolians in what is now Turkey as well as Greeks hollowed out portions of wooden wheels creating the first spoked wheels. These were lighter and made hauling easier. The spoke idea caught on and many wheels today have spokes of one kind or another. Over the years, as trade routes expanded, so did wheel technology.

Although the two-wheeled chariot was developed in Central Europe around 3,900 years ago, it was the Egyptians and Romans who made them into formidable weapons of war. With light-weight but strong spoked wheels the Egyptian chariots were agile, and when pulled by two horses, very fast. The Egyptians were obviously proud of their chariots since parts of six of them were buried with the young pharaoh, Tutankhamen 3,323 years ago.

The Romans also developed sophisticated chariots, generally pulled by two or four horses. Their chariots, built heavier and sturdier with wider and more rugged spoked wheels than the Egyptian chariots, were primarily used for racing and warfare. Chariot racing in Rome became so popular that the Romans built the Circus Maximus, a large stadium where thousands of people could watch the dangerous and exciting sport of chariot racing. In those days, speed was important and the armies with the fastest chariots won the most battles. The Roman armies used their fast, sturdy chariots to conquer much of Europe.

As we progressed through the stone age, the copper age, the bronze age into the iron age which began roughly 3,000 years ago in most places, our tools for sawing and drilling became more sophisticated. We not only were able to make rounder wheels, but since wooden wheels wore out quickly, an important innovation was putting a metal rim around the outside of the wheel. The Celts of Central Europe who became good at metalwork are credited with this innovation around 2,500 to 3,000 years ago. They worked out a system where a heated iron rim was fitted over the wooden wheel and then cooled which tightened it onto the wood. Iron rims increased the life of a wheel by many years. The Celts used the iron rimmed wheels on their chariots and carts, and it is a technology still used today on wooden wagon wheels.

An elaborate grave of a Celtic chieftain found at Hochdorf, Germany dated to about 2,500 years ago, contained a wagon with four sturdily-built wooden spoked wheels, large hubs, and iron rims. It showed that the Celts had reached a high level of wheel technology by that time.

It is interesting that early settlers in the Western Hemisphere who came across the Bering land bridge some 20,000 years ago from what is now Siberia did not make use of the wheel. One theory is that they could not use wheels on carts because there were no horses or other animals to pull them. Except in the Andes Mountains of South America where llamas were used as pack animals, all items too heavy to carry were pulled on sleds by people.

It could be speculated that if Native Americans had horses, they might have developed the wheel as their old-world ancestors had done. Although the species of horse, Equus, that we are used to today, evolved in the Western Hemisphere, most of them migrated thousands of years ago to the Eastern Hemisphere via the Bering land mass. The ones that were left in North America went extinct around 12,000 years ago during the Quaternary Extinction and so were not domesticated by early Native Americans. Horses were not available to pull plows to enhance agricultural output nor to pull wheeled carts.

 Thus, it was Eurasians who domesticated and made use of the horse. Christopher Columbus brought horses back to the Western Hemisphere on his second voyage in 1493. Then a few years later a number of Spanish conquistadores such as Cortex, De Soto, and Coronado spread horses around North America and reintroduced them to the continent and its inhabitants.

For several years following the advent of spokes and the iron rim, wheels did not change much. Chariot wheels used by the Celts and the Romans were not radically different from the wheels on the wagons that carried settlers westward along the Oregon Trail. They were made of wood, had iron rims and wooden spokes, and strong hubs to hold the wheel on.

In 1818 German engineer Karl von Drais patented the velocipede, the first two-wheeled self-propelled machine that became the predecessor of the bicycle. Named the Laufmaschine or running machine and later called the Draisine, it was propelled by the rider running along while sitting on the seat. Drais’s invention had wooden wheels with metal rims and apparently was not comfortable to ride over bumpy roads. But it was faster than walking and the idea of two-wheeled travel caught on. Some people wrapped the wheels with rubber to help absorb the bumps, but the soft rubber of the day wore out quickly.

Throughout the rest of the 19^th century both wheel and velocipede technology grew rapidly. A great improvement came when in 1844 chemist Charles Goodyear patented the vulcanization process that made rubber much harder and more durable. In 1888 pneumatic tire production was begun by John Boyd Dunlop in Belfast, Ireland and immediately his tires became popular on velocipedes, which by then were called bicycles.

By the 1860s and 70s, the development of the gasoline motor led to the first automobiles. Karl Benz, who patented his Benz Patent Motorwagen in 1886 is credited with inventing the first practical automobile. Near the same time, Gottlieb Daimler came out with his version of the automobile. Benz’s vehicle had wire-spoked wheels and solid rubber tires, but it turns out that these lightweight wheels might not have been strong enough to easily carry the motor and passenger, since a later version built in 1888 had spoked wooden wheels with metal rims. Daimlers first car also had spoked wooden wheels with metal rims.

Better wheels were needed for the new modes of transportation. Thus, necessity being the mother of invention, John Dunlop refined his innovative pneumatic tire so that by the 1890s, pneumatic inflatable tires were on nearly all bicycles and automobiles. Other people got into the business as well. In fact, the first patent for putting pneumatic tires on an automobile was granted in 1893 to Andre’ and Edouard Michelin. Today, the Michelin Corporation is one of the largest tire manufacturers in the world.

And it is pneumatic tires that we see on most cars and trucks today. Dunlop’s tires came at the right time to become part of the automobile revolution. Unfortunately, Dunlap was apparently not an astute business man and sold his company to financier Harvey du Cros before it became large and profitable. Although the buyer kept the Dunlop name, unlike other inventors of his day, John Dunlop did not make a fortune on his revolutionary invention.  

Charles Goodyear’s vulcanization had greatly improved the hardness of rubber. But as automobiles with larger engines were able to go faster, an even harder tire was needed. This led Charles Goodrich, the son of Benjamin Franklin Goodrich to establish America’s first tire research center.  Charles built up the B. F. Goodrich Company to become a major tire company that is still in business today.

Charles’s research in making rubber tires harder paid off. BF Goodrich tires were on the first automobile that Horatio Nelson Jackson and mechanic Sewall Crocker drove across America from San Francisco to Manhattan in 1903. The car’s wheels had wooden spokes, metal hubs and inflatable tires. The crew experienced a few blowouts along the way, but managed to keep the tires going. BF Goodrich tires were also on the airplane Charles Lindbergh flew across the Atlantic in 1927.

Another early tire manufacturer that had an impact on the industry was Firestone. Founded by Harvey Firestone in Akron, Ohio in 1900, the company grew to become one of the largest tire producers in the world. The Firestone brand is still popular today and since 1988 has been owned by Bridgestone, the Japanese tire company that is the largest in the world.

The first mass-produced car – the 1908 Ford Model T – had wheels with metal rims, wooden spokes and metal hubs. The tires were 30-inch Firestone clincher tires, that is, they had a hard rubber flange that fit tightly into the metal rim. Whereas most tires today are inflated o about 30 psi, the Model T tires required about 60 psi. Clincher tires are used on many bicycles today.

Tire technology continues at rapid pace. Today we have tubeless tires, radial tires, tires that can run partially deflated, and as suspension technology has improved, there are some cars that use solid rubber tires on their wheels. Wheels have become an indispensable part of human culture. They are everywhere from potter’s wheels, to waterwheels to power gristmills, to toys, to shopping carts, to the big tires that wore out after one landing on the heavy space shuttle that took 2 ½ miles to stop. We have high tech racing wheels and tires and the nickel titanium wheels that will be used on future Mars rovers. After 6,000 years, we innovative humans keep coming up with new designs and uses for our wheels.

Ted McCormack