Monkey business
According to those who research them, capuchin monkeys think only about two things: food and sex. As a result, the vast majority of their behaviors are also geared toward the acquisition of food and sex. Not surprisingly, these desires can be exploited to teach the monkeys other behaviors. However, no one has ever observed animals other than humans to understand and use money (any object that has been assigned a value and that can be traded for another commodity — such as food…or sex).
That is, until now. The New York Times recently reported that Yale economist Keith Chen has managed to teach capuchins to use money. Chen, a self-described behavioral economist, working together with psychologist Laurie Santos, first taught the capuchins that silver tokens were valuable by allowing them to exchange them for treats. According to the article, Chen had no real research plan when he started, he just wanted to give monkeys money and “see what happened”:
It took several months of rudimentary repetition to teach the monkeys that these tokens were valuable as a means of exchange for a treat and would be similarly valuable the next day. Having gained that understanding, a capuchin would then be presented with 12 tokens on a tray and have to decide how many to surrender for, say, Jell-O cubes versus grapes. This first step allowed each capuchin to reveal its preferences and to grasp the concept of budgeting.
Having established monetary value, Chen raised and lowered the price of certain food items to see how the monkeys would respond. Like humans, the capuchins bought more of an item when its price was lowered. So Chen decided to play a little gambling game with the monkeys:
Chen next introduced a pair of gambling games and set out to determine which one the monkeys preferred. In the first game, the capuchin was given one grape and, dependent on a coin flip, either retained the original grape or won a bonus grape. In the second game, the capuchin started out owning the bonus grape and, once again dependent on a coin flip, either kept the two grapes or lost one. These two games are in fact the same gamble, with identical odds, but one is framed as a potential win and the other as a potential loss.
In terms of economics, both of these gambles should be treated equally. But the monkeys strongly preferred to take a gamble on the potential gain than the potential loss — at the same rate as humans under identical circumstances. This, in combination with several other pieces of evidence described in the article, support the idea that the monkeys actually understand money. For example, though they never deliberately save money, the monkeys do steal a token or two here and there. And once, during a chaotic episode in which a monkey took a whole tray of tokens and flung them across the room into the large monkey holding pen, several monkeys quickly scrambled to pick them up. While Chen and his colleagues attempted to get the tokens back, something odd happened:
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.)
If that’s not proof that these monkeys are ready for business, I don’t know what is.
