Economic researchers at Yale managed to successfully train Capuchin monkeys to understand and use currency. The result? The monkeys used their newfound currency to buy sex:

Perhaps the most distinguishing characteristic of money, after all, is its fungibility, the fact that it can be used to buy not just food but anything. During the chaos in the monkey cage, Chen saw something out of the corner of his eye that he would later try to play down but in his heart of hearts he knew to be true. What he witnessed was probably the first observed exchange of money for sex in the history of monkeykind. (Further proof that the monkeys truly understood money: the monkey who was paid for sex immediately traded the token in for a grape.)

I’ll depend on crowdsourcing for the snarky comments here. I’d urge you to read the whole thing. To me what was fascinating is that once they learned the concept of money, the Capuchins pretty much behaved like people. As the article concludes:

But these facts remain: When taught to use money, a group of capuchin monkeys responded quite rationally to simple incentives; responded irrationally to risky gambles; failed to save; stole when they could; used money for food and, on occasion, sex. In other words, they behaved a good bit like the creature that most of Chen’s more traditional colleagues study: Homo sapiens.

(link via Wired Science)

UPDATE (James Joyner): In looking for an illustration for this story (tip: Don’t Google “monkey sex” photos at work…) I came across stories about how shrewd monkeys are at business and their strong sense of fair play. Make of that what you will.