The first known shoes are sandals dating from about 8000 to 7000 BC and found in Oregon, USA in 1938. The world's earliest leather shoe, made from a single piece of cowhide laced with a leather cord along seams at the front and back, was found in a cave in Armenia in 2008 and is believed to date to 3,500 BC. Ötzi the Iceman's shoes, dating to 3,300 BC, had brown bearskin bases, deerskin side panels, and a bark-string net, which pulled tight around the foot. However, tanned leather, the material most commonly implemented for making shoes, does not normally last for thousands of years, so shoes were probably in use long before this. Physical anthropologist Erik Trinkaus believes he has found evidence that the implementation of shoes started in the period between about 40,000 and 26,000 years ago, based on the fact that the thickness of the bones of the toes (other than the big toe) decreased during this period, on the premise that wearing shoes resulted in less bone growth, resulting in shorter, thinner toes. The first designs were simple affairs, often mere "foot bags" of leather to protect the feet from rocks, debris, and cold. Since shoes implement more leather than sandals, their use was more common in cold climates. By the Middle Ages, turn-shoes had been created with toggled flaps or drawstrings to tighten the leather around the foot for a better fit. As Europe gained in wealth and power, fancy shoes turned into status symbols. Toes evolved into long and pointed, often to ridiculous proportions. Artisans created unique footwear for rich patrons, and new styles created. Eventually the modern shoe, with a sewn-on sole, was designed. Since the 17th century, most leather shoes have implemented a sewn-on sole. This remains the norm for finer-quality dress shoes today. Until around 1800, shoes were constructed without differentiation for the left or right foot. Such shoes are now called "straights". Only gradually did the modern foot-specific shoe become norm.
Since the mid-20th Century, advances in rubber, plastics, synthetic cloth, and industrial adhesives have allowed manufacturers to create shoes that stray considerably from traditional crafting systems. Leather, which had been the primary material in original styles, has remained standard in expensive dress shoes, but athletic shoes often have little or no real leather. Soles, which were once laboriously hand-stitched on, are now more often machine stitched or easily glued on.