Wheel and writing

In southern Mesopotamia, by about 3500 BCE, two things arrive close together: the wheel, used on carts and for pottery, and writing, first as pictures pressed into clay to track grain, then as the script called cuneiform.

The wheel's contribution is mechanical advantage for moving weight. A sledge drags. A wheel rolls. Much later, gears, mills, and engines are wheels put to work.

Writing's contribution is larger for everything after it. A method can outlive the person who invented it. Law, math, and recipes survive a generation. The printing press in 1440 has something to print only because this step happened. Before writing, knowledge moves at the speed of speech and dies with memory.

The two inventions are not the same event. Putting them on one card marks the city era in Sumer, when both are in use. Egypt develops hieroglyphs on its own, around the same centuries.