10 Scientific Breakthroughs We Literally Couldn't Live Without

The Wheel
One of the earliest uses of the wheel was on Egyptian chariots. iStockphoto/Thinkstock

We've all heard the expression "no need to reinvent the wheel," meaning that a solution already exists for the problem at hand. This saying has added significance when you consider the many ways in which the wheel improved human life, and how long mankind lived without it.

Archaeologists debate when the wheel was first invented. The earliest evidence of a wheel in human history occurs at about 3500 B.C.E. in Mesopotamia, but this evidence is associated with the wheel's use in pottery-making, not as a tool for transportation. It took another 300 years or so for the people of Mesopotamia to realize that the wheel could also help them to move things from place to place [source: Gambino].

Wheels evolved in a few stages, beginning with the use of logs as rollers to facilitate transportation and continuing on through the replacement of rollers with wheels that rotate on an axle [source: ThinkQuest]. By 2000 B.C.E., wheeled chariots appear in the archaeological record throughout ancient Egypt. Only by then the wheels had spokes, making them considerably stronger and lighter.

The wheel was probably the most important mechanical invention of all time. Just about all modern mechanical devices use the wheel in some way – cars, buses, bicycles, factory machines, toys, wristwatches, movie reels and more. Not to mention the wheel's continued use for pottery-making and transporting goods by cart -- both of which ancient peoples must have appreciated.