That's Not Fair!

If you have two dogs, you probably already know what scientists have discovered: that one gets jealous of the other if they are not treated equally.

Friederike Range, a researcher at the University of Vienna in Austria, published their findings in the Proceedings of the National Academy of Sciences. The report is based on a series of experiments that Range did with her colleagues. The subjects were dogs who knew how to respond to the command "give the paw."

In the experiment, both dogs were asked to "give the paw" but only one was rewarded for the behavior. It didn't take long for the slighted one to catch on and subsequently pause significantly before responding to the command. Eventually, the dogs who did not receive the reward did not look at the researcher giving the command. By looking at the researcher, the dogs would be more compelled to obey, according to Range. Turning their heads away gave them more power and they eventually stopped cooperating.

Scientists have known for quite some time that humans pay attention to inequality. What they didn't realize was that animals do as well. In 2003, Frans de Waal, a researcher at the Yerkes National Primate Center and a professor of psychology at Emory, did a study in which monkeys had to hand a small rock to researchers in order to get a piece of food. All were happy to do this when the rewards were the same--a piece of cucumber. But when one monkey got a grape instead, the others became highly insulted.

"The one who got the cucumber became very agitated, threw out the food, threw out the rock that we exchanged with them, and at some point, just stopped performing," says de Waal.

When Range and her colleagues tested the same protocol with dogs--rewarding some with bread and some with sausage--they did not pick up on the disparity. It was only when some got something and others got nothing, that they reacted.

According to de Waal, both dogs and monkeys live in cooperative societies, so he was not surprised that they would both have some sense of fairness. Which is why, in my house, when one gets a little chicken in their food, they all do. And just because Phoebe eats hers the fastest, does not mean she gets any more.