Nobody really knows who invented the wheel, or how long ago it happened. In the very early days when men and women were trying to move heavy things, they probably rolled them along on logs or round rocks.

It wouldn't have been much of a leap to move to cutting those logs and attaching them to an axle - and making the first ever wheel. At first these wheels were probably solid, like the example on the left. But eventually someone would have found that hollowing out some of the wood or stone made the wheel a lot lighter.

Historians think that the wheel might have first been used in Mesopotamia sometime over three and a half thousand years ago. The Sumerians (the people who lived in Mesopotamia in those times) did not pedal their way through ancient Mesopotamia on bikes, however! They made chariots which were pulled by animals. These animal-powered wheeled chariots and carts helped haul goods and people for thousands of years.