Like a lot of life-changing products, shoes are much more precise now than when they were first brought to market. In fact, it wasn’t until 1860 that left and right shoes were made en masse after centuries of a different approach. From the 16th century until the Industrial Revolution, nearly all shoes were “straights” made to be worn on either foot. 

Of course, this wasn’t because cobblers and consumers were under the false impression that their feet were identical. It’s just that straights were more economical and easier to produce than mirrored shoes — something of a one-size-fits-all philosophy. Right and left shoes date back to the ancient world, including the Romans, but “straights” were preferred in the leadup to the Industrial Revolution, whose many factories then made it easier to mass produce lefts and rights.

Footwear has existed in one form or another for at least 50,000 years, when people first began protecting their feet from frigid conditions; footwear with actual soles is believed to date back around 40,000 years. The Fort Rock sandals, which were discovered in a cave in Oregon in 1938, are the oldest known shoes in the world at more than 9,000 years old.