The topper to Dubner's stories to the AIIM audience involved an incident in which one of the capuchins threw a tray of washers that ended up spilling into the general population area. The monkeys, as expected, fought for the coins and, except for one, were easily bribed with the opportunity to purchase food in order for researchers to get the washers back.
"Out of the corner of his eye, Chen saw that one monkey gave a coin to another (instead of rushing to exchange it for treats.) He thinks, am I witnessing the first instance of monkey altruism? No. He was actually witnessing something he said he really wished he hadn't seen," said Dubner.
After a brief grooming ritual, the monkeys who exchanged the coin started to have sex. Immediately after the incident, the paid monkey went over to Chen to get food in exchange for returning the coin, Dubner said.
