Menger provides an evolutionary theory of money&#x27;s emergence and does devote a chapter to the precious metals, but historically all sorts of commodities have served as media of exchange in various circumstances.<p>The primary standards of international trade during the mercantilist and merchant capitalist eras were silver bullion coins like the Spanish dollar.<p>Formal gold specie standards arose during the 19th century by royal fiat and soon displaced other currencies.<p>It is likely that free currencies would settle on precious metal convertibility because of prior art, but there&#x27;s no reason to presume it has to be gold in particular, or to single out gold as being &quot;special&quot;.