Chimpanzees refuse a less-preferred food reward from a human distributor - but not a machine - if they could have been given a better one

Researchers of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, show that unlike humans, chimpanzees do not compare their payoffs to the payoffs of a social partner. They do, however, display a different, potentially evolutionarily more ancient, form of fairness: They react with disappointment if someone fails to take their personal preferences into consideration when distributing resources.