Proceedings of the National Academy of Sciences (PNAS), suggest a long evolutionary history of the human aversion to inequity, as well as a shared preference for fair outcomes by the common ancestor of humans and apes.
Click here to watch a video of the experiment.
“We used the Ultimatum Game because it is the gold standard to determine the human sense of fairness," says lead author Darby Proctor, a post-doctoral fellow at Yerkes. "In the game, one individual needs to propose a reward division to another individual and then have that individual accept the proposition before both can obtain the rewards. Humans typically offer generous portions, such as 50 percent of the reward, to their partners, and that’s exactly what we recorded in our study with chimpanzees.”
"Until our study," adds co-author Frans de Waal, "the behavioral economics community assumed the Ultimatum Game could not be played with animals, or that animals would choose only the most selfish option while playing. We've concluded that chimpanzees not only get very close to the human sense of fairness, but the animals may actually have exactly the same preferences as our own species."
For purposes of direct comparison, the study was also conducted separately with human children.
Capuchin economics: Monkeys on unequal pay
Sharing ideas about the concept of fairness