Representative money is widely believed to have originated in ancient Sumer where small baked clay tokens in the shape of sheep or goats were used to replace barter in trade. Over time, they were sealed in clay vessels which contained a certain number and had that number written on the outside - but it was only possible to verify the number of tokens inside by shaking the vessel and guessing, or by breaking it. At which point, the number written on the outside originally became subject to doubt. Apparently, however, this system was good enough to have discouraged much counterfeiting - penalties for "short-sheeping" or selling the same goat twice were quite severe, and often such activities in ancient societies were thought to offend one or more gods.
Later during the crusades, representative banking notes were established by the Knights of the Temple of Solomon (the Templar Knights), so that pilgrims could protect themselves from robbery along the pilgrimage to the holy lands. Pilgrims would deposit an amount of gold in a Templar monastery in Europe and were given an equivalent in banking notes, then would "cash in" these notes for the amount of gold once they had arrived in the holy lands. The notes would have been worthless to any highway robbers and therefore were not taken. This banking system and the presence of paper monies has evolved into our modern banking system.
In the late 19th and early 20th century most currencies were examples of representative money in that they were based on the gold standard in which a currency could be exchanged for a fixed amount of gold, at least in theory. In fact, in many countries, such exchange was discouraged, difficult and likely almost impossible except for a few with access to the commodity markets in major capital cities, or in some cases, any but those in government or with proven foreign exchange needs that were supported by the government.
Most nations of the world shifted entirely to fiat money by 1976. Often, this shift occurred in stages. For example, the United States economy functioned on both fiat money and several types of metal-backed representative money, from 1862 to 1971. In 1862, during the U.S. Civil War, fiat money "greenbacks," backed only by government credit, were first issued. In 1971, the international gold standard (Bretton Woods system) was officially abandoned by the U.S., in an act termed the Nixon shock. However, U.S. citizens were barred from trading directly in gold after 1933, and had not been able to redeem their dollars for gold. Until 1964, U.S. silver certificate dollars (a type of representative money) were redeemable for silver dollars (at that time, the only silver U.S. coin), under a silver standard. After this time, however, U.S. dollars (as Federal Reserve Notes) were not redeemable in any quantity of any precious metal, and thus were no longer a representative money, but entirely a fiat money. Such legal changes in money types are typical, and characterize the long shift from commodity money to representative money to (in the modern day) fiat money.
While representitive money is not currently used as the official currency of any nation, a few theorists of green economics and natural capitalism have argued for its return, some of whom suggest a form of money based on ecological yield. They argue that the outputs of "natural capital" are the only genuine commodities - air, water, and renewable energy we consume being mostly interchangeable when they are free of pollution or disease. However, since such goods cannot be held directly, it is common to suggest that representative money be issued based on enhancing and extending nature's services, giving one the right to receive the yield as benefit. They argue that reframing political economy to consider the flow of these basic commodities first and foremost, avoiding use of military fiat except to protect "natural capital" itself, and basing credit-worthiness more strictly on commitment to preserving biodiversity rather than repayment of debt, as in the current global credit money regime anchored by the Bank for International Settlements, would provide measurable benefits to human well-being worldwide.
Critics of this type of proposal often note that, as with other transitions from commodity to representative money, inadequate substitutes will be made on a "just trust me" basis - as per Gresham's Law which states that bad money drives out good. Other proposals, such as time-based money, rely on the availability of human labour as a commodity, especially within a community, which is presumably harder to guarantee access to, but also harder to steal. Still others deny the utility of commodifying labour as such, and suggest making free time the standard, since physical capital used for leisure, sport, art, theatre, and other forms of play is commodifiable and possible to control.
Some, in environmental economics, argue that the life of the individual human being and the natural ecologies are already both treated as commodities in global markets. They argue that to put a price on both is the most reasonable way to proceed to optimize and increase that value relative to other goods or services. This has led to efforts in measuring well-being, to assign a commercial "value of life", and to the theory of Natural Capitalism - which focuses predictably on energy and material efficiency, i.e. using far less of any given commodity input to achieve the same service outputs as a result. Michael Benedikt has proposed a theory of value along these lines. An example of this view is held by Indian economist Amartya Sen, who discussed the relationship between access to commodities, labour, and "the right to live as we would like" in his 1999 book "Development as Freedom", arguing that human free time was the only real service, and that sustainable development was best defined as freeing human time.