Shelling Out: The Origins of Money Nick Szabo Originally published in 2002

The precursors of money, along with language, enabled early modern humans to solve problems of cooperation that other animals cannot – including problems of reciprocal altruism, kin altruism, and the mitigation of aggression. These precursors shared with non-fiat currencies very specific characteristics – they were not merely symbolic or decorative objects.

https://nakamotoinstitute.org/shelling-out/