Bros, I wasn't sure if this belonged in the Monger's Lounge, Veggie Cafe, or News. And seeing as we're all amateur Anthropologists, that is students of human (okay, well...maybe only working girls) behavior and the article involves Prostitution--well, of at least the mammalian variety--I figured I'd try here. (Mods, please forgive me if this is a dup post, but I've gone pretty far back in into these pages and didn't see this article mentioned.)
How scientists taught monkeys the concept of money. Not long after, the first prostitute monkey appeared
Relevant excerpt from ZMEScience.com's article (link above) regarding a 2005 Yale University Joint Pscyhology & Economics study:
"
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…"