Thing axe-heads themselves would serve indeed have served in some societies and over a very large area of south-east asia cowry's shells were used the most often quoted form of primitive money.

"This results in us being motivated to go grab that potentially rewarding thing, be it food (or any other primitive reward) or money, " said Kuhnen, who studies how risk plays out in the brain.

Small seashells were often used as a primitive kind of money.