Few of the world’s currency systems are more unique and attractive than the rye stone circles used on the tiny western Micronesian island of Yap. Carved from limestone slabs, donut stone circles measure up to 4 m (12 ft) in diameter, although they come in shapes from Orio to Cartwheel or Van. The rocks were not actually forged on Yap Island, where there is no metal or similar rock, but came from Anagumang Island, about 640 kilometers (~400) miles away. According to a version of the original story, the coin originated 500 years ago when a team of explorers from Yap traveled to Anagumang.
Surprised to see the limestone treasures on the island, the people of Yap were allowed to dig and carve the limestone in exchange for the goods and services of the people of Anagumang. The carved stones were sent back to Yap against the sea, which is no small feat considering it weighs more than an elephant. This rigorous process of obtaining judgment stones enriched them with values. Like giant coins, rye stones are exchanged as a symbol of value during culturally important ceremonies such as weddings, inheritances, settlement of disputes, or political transactions. Rye stones are still used today for formal exchanges, although cash is commonly used in everyday life on the island.
However, depending on the size and weight of the rye stones, they are not carried in wallets and are usually fixed outside significant places such as government buildings or communal paths. Knowledge of the ownership of what is recorded in the public oral tradition is about transferring stones to a public event for all to see. In 2019, archaeologists and economists from the University of Oregon studied this financial system and argued that it has some deadly similarities to cryptocurrencies such as Bitcoin.
Bitcoin is a decentralized digital currency that does not require a central authority like any bank to process transactions. To monitor transactions, the exchanges are encoded in a public transaction book, known as a blockchain, which is somewhat like a shared spreadsheet that is constantly updated. Transactions are collectively verified by everyone in the system, and the history of all transactions is available to everyone. Since share knowledge and communal beliefs in the currency are at the heart of the judgment stone, this team of researchers argued that it is uniquely similar to the oh-so 21st century concept of cryptocurrency.