The Origin of Money

Once upon a time, some guy had an orange and you wanted it.  So you offered to trade a banana for his orange.  But your banana was way back at your hut.  So you picked up a seashell or something and handed it to him in exchange for his orange.  You promised to go get your banana and deliver it later.  That is the origin of money.  The seashell was a symbol that represented a contract to deliver a banana.

Alternatively, both people could have yelled out to the surrounding village that you owed that person a banana.  Then you didn't need the seashell.  Everyone knew you owed that person a banana.  Then you go back to your hut the next day and get the banana.  Then you yell out to the village that you paid back the banana.  Let's hope that banana did not go bad overnight.

Would it be possible to have a computer store these transactions so the villagers wouldn't have to remember?