Ducks and Economics

From Science:

The findings, Ross says, suggest that low-status gorillas use the game as a sort of ego boost. They can hit a high-status individual without repercussions, she says, and that gives them a feeling of superiority, even if it’s only temporary. And that means that gorillas are aware of inequities in their society, Ross says, marking the first time that such cognition has been observed in gorillas in a nonexperimental setting. The researchers will report their findings online tomorrow in Biology Letters.