WORLD CIVILIZATION

Detailed explanation-1: -The wheel was invented in the 4th millennium BC in Lower Mesopotamia(modern-day Iraq), where the Sumerian people inserted rotating axles into solid discs of wood. It was only in 2000 BC that the discs began to be hollowed out to make a lighter wheel. This innovation led to major advances in two main areas.

Detailed explanation-2: -The wheel, plow, and writing (a system that we call cuneiform) are examples of their achievements. The farmers in Sumer created levees to hold back the floods from their fields and cut canals to channel river water to the fields. The use of levees and canals is called irrigation, another Sumerian invention.

Detailed explanation-3: -Though often thought of as one of the earliest inventions, the wheel actually arrived after the invention of agriculture, boats, woven cloth, and pottery.

Detailed explanation-4: -Early wheels were simple wooden disks with a hole for the axle. Some of the earliest wheels were made from horizontal slices of tree trunks. Because of the uneven structure of wood, a wheel made from a horizontal slice of a tree trunk will tend to be inferior to one made from rounded pieces of longitudinal boards.