10 Weirdly Human Animal Behaviours
5. Monkey Learns How To Use Money... And Hires A Prostitute
It's supposedly the oldest profession in the world, but it looks like it's also a profession that can transcend species.
Back in 2005, a psychologist and economist got together and decided the time was ripe to teach monkeys how to use money.
Keith Chen and his colleague Laurie Santos, trained a troop of capuchin monkeys to use a made-up currency of little silver discs with a hole in the middle. The monkeys would trade the disks with the researchers for grapes and little cubes of jelly.
The system was pretty sophisticated, even by some human standards, with all kinds of price shocks and inflation. For example, if the price of jelly went up, the capuchins would prefer to buy the "better value" grapes - they even learned how to gamble.
This was all pretty par for the course, but there was one result that was particularly unexpected. Chen, one day, just happened to spot a transaction being made between two monkeys out of the corner of his eye. He saw a male monkey exchange some silver tokens for sex with female monkey.
What's more, after business was done, the female monkey used the silver tokens to buy more grapes and jelly.