The earliest known shoes are sandals dating from about 8000 to 7000 BC and found in Oregon, USA in 1938.[5] The world's oldest 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.[6][7][8] Ötzi the Iceman's shoes, dating to 3,300 BC, featured brown bearskin bases, deerskin side panels, and a bark-string net, which pulled tight around the foot.[7] However, tanned leather, the material most commonly used 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 use of shoes began 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.[9][10] The earliest designs were simple affairs, often mere "foot bags" of leather to protect the feet from rocks, debris, and cold. Since shoes use more leather than sandals, their use was more common in cold climates. By the Middle Ages, turn-shoes had been developed 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 became status symbols. Toes became long and pointed, often to ridiculous proportions. Artisans created unique footwear for rich patrons, and new styles developed. Eventually the modern shoe, with a sewn-on sole, was devised. Since the 17th century, most leather shoes have used a sewn-on sole. This remains the standard for finer-quality dress shoes today. Until around 1800, shoes were made without differentiation for the left or right foot. Such shoes are now referred to as "straights".[citation needed] Only gradually did the modern foot-specific shoe become standard.
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 techniques. Leather, which had been the primary material in earlier 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 simply glued on.