To be honest, we still don't know exactly when and where the wheel was invented. But the oldest archaeological evidence of a wheel used for transportation was uncovered in Budakalász, Hungary, at the edge of the Carpathian Basin. A bunch of miniature carts with wheels were found in a cemetery of an ancient mining community dated to 3900 BC. If these models were depictions of full-sized carts, they would have been quite useful in hauling copper ore out of the Carpathian Mountains.
When we think about how the wheel came about, we think of ancient people moving large items by sticking logs underneath to use as rollers. It wasn't an everyday occurrence, though, and was only used for object too big or heavy to be lifted by a team of men or dragged by draft animals. Still, rollers would be a help for miners hauling heavy copper ore. But how did rollers become wheels? Or more precisely, how did rollers become the wheel-and-axle used in the miners' carts? It probably wasn't one very smart miner who came up with the idea himself, but an evolution of sorts that went through several stages, each consisting of design, use, and incremental improvement. In other words, trial and error. Read how that process may have gone all those years ago at the Conversation. -via kottke
(Image credit: Kai James via DALL·E)