He got that bread crumb for free!
Sensitivity to inequity is considered to be a crucial cognitive tool in the evolution of human cooperation. The ability has recently been shown also in primates and dogs, raising the question of an evolutionary basis of inequity aversion.
Viennese biologists have presented evidence in PLoS ONE that two bird species are sensitive to other individuals’ efforts and payoffs. A pair of biologists at the University of Vienna trained six carrion crows and four ravens to exchange pebble tokens for food. The researchers then created same-species pairs for a series of experiments.
I don’t want your reward
When the birds saw their partners getting food for free, without having to exchange tokens, they tended to exchange tokens less often. Sometimes the birds that got the short shrift even gave away tokens, but refused to take their reward.
Other research has suggested that a sense of equity evolved several times in unrelated animals, the University of Vienna researchers write. Knowing what’s fair is linked to cooperative behavior in species, they say, and that makes sense with crows and ravens, which form alliances and share food and information.
