No one knows exactly when people invented clothes. Usually, the origin of clothing is dated back to 100,000 years ago. According to archaeological research, “prehistoric hunters may have worn the skins of bears or reindeer in order to keep warm or a sign of personal skill, bravery, and strength” . The needle was invented by the end of the Old Stone Age – about 25,000 years ago. At about the same time, people started to make yarn from plants or from the fur or hair of animals. They had begun to raise plants and started to herd “wood-producing” animals like sheep.
Of course, clothes have a very important biological function, but it appears that “even in cold climates, some people seem more interested in decorating their bodies than in protecting them. In the 1830s the British biologist Charles Darwin (1809-82) travelled to the island of Tierra del Fuego off the southern tip of South America. There he saw people who wore only a little paint and a small cloak made of animal skin, in spite of the cold rain and the sleet. Darwin gave the people scarlet cloth; they took it and wrapped it around their necks, instead of wearing it around the lower body for warmth. Despite the cold weather, the people wore clothing not for protective reasons, but primarily for decorating their bodies and making them appear attractive” .
Humans “have used clothing to define our kind (especially to differentiate ourselves from animals), and to differentiate ourselves from each other” . In all societies and cultures, “dress characterizes group membership and beliefs”. “Shamans … have always worn special clothing to identify themselves. … Motorcycle gang members … wear leather jackets, boots, and various items such as brass knuckles to convey toughness and group identity” .
It is not a great discovery that “what makes nudity appealing … is the absence of clothing”. “Nudity is the oppositional counterpart to clothing”. Clothing and nudity “constitute a single system of meaning” .
So what does nudity mean? There is a simple answer: “nudity is associated with sex because … one usually becomes nude in order to engage in sex” . Despite the fact that one may find this explanation exhaustive, there’s another point of view on nudity.
It was noticed that “in a clothed society, … nakedness is special, and can be used as a “costume” . In other words, nudity can be “imagined as a form of clothing” . If so, when was it appropriate to wear this “costume”, in historical perspective?
“In anthropology, for example, nudity-as-clothing can appear as the category of “ritual nudity”, in which the theorist analyses the way nudity can function as a kind of costume in ritual or magic” . “In Greece the remarkable innovation of athletic male nudity, which surely originated in a ritual, religious context, developed a special social and civic meaning. It became a costume, a uniform: exercising together in the gymnasia marked men’s status as citizens of the polis and as Greeks”. Men “attended the gymnasium, and proudly wore the “costume” that was appropriate for this place”. “Nudity as a costume was fashionable” .
“Throughout the sixth century B.C., black-figure Attic vases regularly show athletes competing in the nude, as well as nude gods, heroes, mortals, revelers, etc.” . “In the convention of heroic nudity, gods and heroes were shown naked, while ordinary mortals were less likely to be so, though athletes and warriors in combat were often depicted nude” .
In this context, the “modern” attitude towards nudity seems disappointingly primitive. Nudity, a “costume” related to magic and heroes, has lost most of its meanings. It’s time to find them again.
 Marcel Danesi, The Quest for Meaning: A Guide to Semiotic Theory and Practice, University of Toronto Press, 2007
 Ruth Barcan, Nudity a Cultural Anatomy, Berg, 2004
 Yahoo Answers: Why most peoples always associated nudity with sexual?
 Larissa Bonfante, Nudity as a Costume in Classical Art, American Journal of Archaeology, Vol. 93, No. 4, 1989
 Nude (art) – Wikipedia, the free encyclopedia