The invention of the wheel

The story

A discovery in the peat

In 2002, on the outskirts of Ljubljana, the capital of Slovenia, some archaeologists were exploring a vast wetland called the Ljubljansko Barje, the “Ljubljana Marsh”. Until not long before it had been a lake; then the rivers had filled it with mud and peat. Long ago, among the reeds, groups of farmers lived and built villages on stilts. Digging in the peat, more than two metres down, someone touched something wooden, curved and smooth with a spade. It was a wheel. And beside it, still in its hole, was its axle.

That wheel, washed and studied, proved to be a treasure. It is about 5,150 to 5,200 years old (the researchers used radiocarbon and dendrochronology, that is, the reading of tree rings). It is made of two ash planks, joined by two crosspieces, and has a diameter of about seventy centimetres. The axle, of oak, is more than a metre long. It is the oldest wooden wheel with its axle ever found, and it is on show in the City Museum of Ljubljana.

The peat worked the miracle. In wet ground, with no oxygen, wood does not rot: it stays intact for thousands of years. Almost everywhere in the world ancient wooden wheels have vanished, because wood wears away. That is why they are so rare.

A late and difficult invention

It might seem that the wheel is a natural idea, but in fact it came very late. Human beings had already invented the bow, the boat, cloth and pottery before thinking of a cart. The reason is that a round disc is not enough. You have to make the wheel turn around an axle without it stopping or jamming. The wheel and the axle have to be precise, with well-smoothed surfaces and a little space to move. You need a road to travel on and an animal to pull. First you needed the herding of oxen, which happened about 10,000 years ago, and then you had to learn to make them work, which happened thousands of years later.

For this reason the wheel is not the invention of a lone genius. It seems to have appeared little by little, perhaps from an idea like the rollers made of logs that were put under heavy objects to drag them.

Where and when

The oldest evidence comes from places very far from one another, all between about 3500 and 3000 BC. On a pot found at Bronocice in Poland, about 5,500 years old, there is a drawing that looks like a four-wheeled cart. In northern Germany, at Flintbek, traces of ruts left by carts in the ground have been found, dating from more or less the same period. In Mesopotamia, in the city of Uruk, drawings of sledges and carts appear on the clay tablets, around 3200 BC. We do not know where the wheel was invented: perhaps in several places, perhaps in just one, from which it spread very quickly. Scholars argue about it.

Perhaps the first use was the potter's wheel, a disc that turns and makes it possible to make regular pots. For others the wheel arose in mines, to carry the ore. This too is a matter of hypotheses.

From disc to spoke

The first wheels were solid discs, made of one or more wooden planks. They were heavy and slow. Only much later, around 2000 BC, did spoked wheels appear, lighter and faster, in the steppes between Russia and Kazakhstan, where the first light war chariots, pulled by horses, were built. With the spoked wheel came war chariots, which changed the armies of antiquity.

There is a curious fact: the wheel was not invented everywhere. In the American civilisations before Columbus the wheel, as far as we know, appears only in toys, such as little terracotta animals with wheels found in Mexico. They had no large draught animals, such as oxen and horses, and without them the wheel was of little use. The great American cities were therefore built without carts.