So scientists taught capuchin monkeys the notion of money–they could use tokens to “buy” food. Then this happened:

Something else happened then too, tough , in what’s maybe the most evident form of one’s grasp upon currency. The idea is that you can use money as a form of currency to exchange for goods or services, as in not just food. Well, one of the researchers, during the chaos event, observed how one of the monkeys exchanged money to another for sex. After the act was over, the monkey which was paid immediately used it to buy a grape…

Ayn Rand, who has written a thing or two about the value of money, would probably be nodding her head in agreement (and then pen another violent rape scene).