Monkey Money

Capuchins are small monkeys endemic to the rain forests of Colombia, Venezuela, and the Central American isthmus. They look like the fellow to the left, an adult male, who is about two feet long, not counting his long tail. Cute. Smart, despite a very small brain that seems hard-wired for two functions -- eating and mating.

But he's smart enough, it seems, to learn how to use currency. Scientists taught a troop of seven of these monkeys that they could exchange small metal discs for food. Give the scientist a disc, get some food. Got no disc? Get no food. This is a big deal for the capuchin, which in an environment of plentiful food will literally eat until it vomits and immediately begin eating new food again.

So every day, the monkeys would be given an allowance -- twelve tokens each. They could "buy" different kinds of food, and quickly learned how to react to changes in market conditions (simulated when the researchers changed the amount of different kinds of food given in response to tokens). The monkeys also were taught how to gamble, but did not like to most of the time, preferring the certainty of reward of "market" exchanges. They also did not demonstrate much affinity for saving tokens for future rewards. They learned how to steal tokens from one another so they could get more food. But the really amazing part is this -- remember how they're wired to do nothing but eat and mate? Well, after teaching the monkeys what money was, sex was monetized as well:

Once, a capuchin in the testing chamber picked up an entire tray of tokens, flung them into the main chamber and then scurried in after them -- a combination jailbreak and bank heist -- which led to a chaotic scene in which the human researchers had to rush into the main chamber and offer food bribes for the tokens, a reinforcement that in effect encouraged more stealing.

Something else happened during that chaotic scene, something that convinced Chen of the monkeys' true grasp of money. 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.)

Prostitution! The scientist had tried to soft-pedal this behavior and not leak it out, but I think it's an enormously important thing to have observed. It proves, more than anything else, that the monkeys had been taught what money was.

It would be no particular surprise if the monkey exchanged sex for food; that has been well-documents in many species. But this monkey exchanged sex for "monkey money" and proved she knew what she was doing when she demanded food in exchange for the money. The scientists taught basic currency economics to two-foot long monkeys. This may not be natural, instinctual behavior, but once it was taught, the knowledge is transmitted from monkey to monkey somehow and individual monkeys figure out new dimensions of an economic system on their own once they're in it.

We know that a wide variety of animals engage in politics, for instance -- to take just one example, packs of dogs or wolves in the wild periodically used ritualized combat to determine which animal will be the leader of the pack, and other dogs obey commands given by the "top dog" without further conflict (including a dog who once was the leader and has been recently displaced).

Dolphins engage in playful athletics like surfing, and in recreational sex. Indeed, many dolphins are bisexual and will have recreational sex with dolphins of the same gender as often as with the opposite gender, and without regard for whether the female (if any is involved) is fertile at the moment.

African monkeys have been observed to eat certain berries known to have depressant effects on their physiology, apparently to enjoy the high created by taking these "drugs;" some have even been observed to habitually seek out and eat the berries despite the loss of opportunities for food, sex, or safety, and thus could reasonably be called "addicts."

Whales communicate with sophisticated "songs" that vary by the whale's location above or below ocean's thermocline and so seem to distinguish between short-distance and long-distance communication. What they are saying to one another across hundreds of miles of open ocean is still a great mystery to us; maybe they wait until they're down deep to gossip about the humans so we can't overhear them.

Perhaps a great many sophisticated behaviors are really more deterministic than we'd like to believe. If politics, drug addiction, long-distance communication and casual dating are not unique behaviors to humans, why should economics be any different?