Early man had to rely on his own muscle-power to carry objects, but over thousands of years tamed
animals, such as horses, oxen and donkeys, elephants and camels. In order to be able to transport more
goods than an animal could carry on its back, sledges and hurdles that could be pulled behind the animal
were eventually invented, as well as such instruments as ploughs to make agriculture easier. Where
sledges were not suitable, such as on rough ground or sand, the could roll heavy objects along on top
of logs, continually taken from behind the object as it passed and placed in front of it. It is thought that
stones for both the pyramids and Stonehenge may have been moved using this technique. Eventually,
someone realized that attaching the logs, or sections of log, to the object would be more efficient and

the wheel was born.