Overhead, orange-billed toucans fly past, while troops of capuchin monkeys chatter nosily in the dense canopy.

BBC: Livin�� la vida Bonito

The capuchin monkeys were upset, selfishly, when they didn't get the grapes that their neighbors received.

CNN: Morality: It's not just for humans

Sarah Brosnan, currently at Georgia State University, found that capuchin monkeys reacted dramatically to being treated unfairly.

BBC: Puppet experiment suggests humans are born to be fair

Scientists from Stirling University and Kyoto University in Japan observed capuchin monkeys responded best to humans who were helpful to others.

BBC: Capuchin monkeys 'shun selfish humans', study suggests

In a 2008 study, de Waal and colleagues put two capuchin monkeys side by side and gave them a simple task to complete: Giving a rock to the experimenter.

CNN: Morality: It's not just for humans

Researcher Keith Chen at the Yale School of Organization and Management grabbed headlines last summer when he released a study showing that capuchin monkeys could be trained to use shiny metal disks just like human money.

FORBES: Primate Economics

If she's going to say yes, she's going to say yes (or ... there's always the other possibility), and a cast of thematically dressed thousands and dancing capuchin monkeys, with celebrity cameos, won't top the fact that the person she loves has just floated the notion of spending eternity together.

CNN: What's with public marriage proposals?

After training the monkeys to trade pebbles for slices of cucumber, the capuchin happily played the game.

FORBES: Move up http://i.forbesimg.com t Move down