Currency, Financial Crisis, and CypherpunksGold became a currency about 2000 years ago. Around 1000 years ago, silver was gradually adopted as the general equivalent for market circulation. In ancient times, humans also used livestock, slates, shells, jades as currencies. In the past, humans chose a substance as currency basically based on its rarity and stability. As the economy developed and trading flourished, the barter form was gradually replaced by paper money or credit vouchers. And th...