From The Far Side to The Flintstones to The New Yorker, the popular imagination puts the invention of the wheel back when dinosaurs roamed the earth. (Uphill both ways, in the snow, same 3rd grade teacher as your parents, etc.) The Paleolithic Era, the actual stone age, starts rougly 63 million years after the last of the Cretaceous dinosaurs. It spans 2.6 million years from when early hominids began to use stone tools to the end of the last ice age. But stone tools are not good for precise stone work, and did not advance much beyond hammers, axes or spears, and needles during this period. Stone wheels are out. The earliest wheels were almost definitely wood.
More conventional anthropology explains the invention of the wheel as a long process during the dawn of civilization. The first step was probably dragging large objects on the ground, possibly on a sled or sledge. Later, loads were placed on rollers. But continually running the last roller back around to the front is a slow, tedious, exhausting process. Grooves in the rollers and runners under the cargo would increase the distance over the ground between resets, but there’s no doubt early loadmasters were thinking about how to keep rollers permanently underneath.
From a log with grooves, it’s not a big jump to a wheel and axle, and from a slot dropped over a groove, it’s not a big jump to a solid bearing. The problem was the small tolerances needed to make a wheel/axle/bearing assembly work well. Once again, stone tools are out. In fact, the wheel probably doesn’t appear until after bronze carpentry tools. The earliest known wheel, along with a square axle, was found in the Ljubljana marsh in Slovenia, and has been dated to roughly 3100 BC. It only slightly predates other ancient wheels found in Central Europe, Caucasus, and Mesopotamia. This, along with its fairly sophisticated construction indicates that cruder versions existed even earlier, and quickly rolled out through the world.
With wooden construction in mind, up to and including copper fasteners, many ancient depictions of vehicles look similar to the carts we associate with the Middle Ages. Wooden wheels, solid or spoked, matched the conditions of road surfaces and draft animals for thousands of years, through antiquity, the Dark Ages, the Renaissance, and even the dawn of the automobile. It was the combination of higher performance engines, higher loads, and modern Bessemer steelmaking that finally pushed wood out of railroad and automobile applications.
Stone wheels have yet to catch on.
On The Move: A Chronology Of Advances In Transportation, Leonard C. Bruno, Gale Research Inc., Detroit, 1993
How the Ancient Sumerians Got Humanity Rollin’!, by Jinni Bradfield, AntiquityNow.org
Mesopotamia Wheels, AncientMesopotamians.com
Why It Took So Long To Invent The Wheel, Natalie Wolchover, Scientific American, March 6, 2012
Slovenian Marsh Yields World’s Oldest Wheel, American Home, March 27 2003