When humans domesticated dogs, thus separating them evolutionarily from wolves, we changed a lot about them. We gave them floppy ears, for example, and made them more subordinate. We also thought we might have given them unique cooperation skills. If dogs had to work alongside humans in order to be fed, maybe they evolved to have a sense of equity as well. We both work, we both get rewarded. If that hypothesis were true, though, wolves wouldn't have the same desire for equity. But if dogs' cooperative abilities are a carry-over from their wolfish brethren, wolves and dogs should both exhibit a sense of fairness.