Chimps Have an Innate Sense of Fairness

Human ideals about fairness may not be so human after all


Human ideals about fairness may not be so human after all, new research finds. A sense of innate fairness may have evolved long before Homo sapiens began playing rock-paper-scissors to decide which team would bowl first. Chimpanzees, the BBC reports, beat us to it. The great apes possess an innate sense of fairness that researchers think likely served as an important foundation of building cooperative societies such as our own.

To tease out the specifics of chimps’ sense of fairness, researchers challenged the animals to the “ultimatum game.”

During the game, one participant is given an amount of money and asked to “make an offer” to the second player. If that second player accepts the offer, the money is divided accordingly.

But, if the second player refuses that offer, both players receive nothing. This is the basis of the fairness versus economics quandary; if the first player proposes a selfish, unequal offer, the affronted recipient might refuse.

And this is exactly what happens in humans. Although it makes economic sense to give away as little as possible and accept any offer that’s proposed, people usually make roughly equal, or “fair” offers, and tend to refuse unequal or “unfair” offers.

For monkeys, the researchers tweaked the game to include banana slices rather than money. A bit abstractly, colored tokens represented banana slices, which the researchers taught the chimps to recognize as such. Taking a white token meant the food got split up equally, while blue tokens gave the first chimp all of the tasty rewards. The researchers presented one chimp with the two tokens. The chimp would then chose a token and offer it to its partner. Just like in the human version, the partner needed to accept the token before either animal received a reward.

From observing three pairs of chimps, the researchers saw that the teams tended to work fairly together and equally share the food reward. The researchers guess that sharing, cooperation and fairness helped chimp ancestors survived, since groups that worked together to care for young, find food and defend against predators had better odds for passing on their genes to the next generation. A strong sense of fairness and tendency towards sharing likely existed in chimpanzees at least as long as the time at which humans and chimps split off from the evolutionary tree, the researchers think.

The researchers also noted to the BBC that in tests with 20 children between the ages of two and seven, just like the chimps, the youngsters ”responded like humans typically do.”

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