June 8 (UPI) -- Humans and primates have a finely tuned sense of inequity. New research suggests dogs and wolves also possess a sense of fairness -- or lack there of.
Previously, researchers have hypothesized dogs gained a sense of inequity through domestication. But the latest study -- published in the journal Current Biology -- shows the sense is equally strong in dogs and wolves, suggesting a sense of fairness is wired in the genes of canines.
In tests, scientists found wolves trained to press a buzzer refused to participate after realizing the action resulted in a treat for their partner but nothing for themselves. The test results were the same for dogs and wolves with the same upbringing.
When researchers tested dogs and wolves without a partner, the canines were more willing to continue their training, continually pressing the buzzer despite not receiving a treat.
"This showed that the fact that they themselves had not received a reward was not the only reason why they stopped to cooperate with the trainer," Friederike Range, a scientist at the Wolf Science Center of the University of Veterinary Medicine in Vienna, Austria, said in a news release. "They refuse to cooperate because the other one got something, but they themselves did not."
Both the dogs and wolves refused to participate in the experiment even when they received a treat that was smaller than that of their partners.
"This reaction has not been shown in experiments so far. But it confirms even more clearly that wolves and dogs really understand inequity," said researcher Jennifer Essler.
The research also revealed the importance of hierarchy among wolves, as high-ranking wolves were quicker to grow impatient with the experiment.
"High-ranking animals become frustrated more quickly by inequity because they are not used to this situation: not receiving something at all or only of lower quality," said Range.
Wolves, like dogs, are highly social animals and cooperate with one another to survive. Previous research suggests a sense of inequity is essential to effective cooperation.