lavash

“Fairness” and “Justice” are hard to measure and test for but there are plenty of tests on empathy in animals that you could define as “fairness / justice.” 

A popular one is the drowning rat experiment (no rats actually drowned)  done by researchers at the Kwansei Gakuin University in Japan. They place one rat on one side of a box that was dry container and another in the side of the box with water (which rats strongly dislike) forcing it to trend water. The rat on the dry side of the box could push open a door and let the rat climb through to the dry side.

Showing that the dry rat responding to the distress of the wet rat and helped! Further confirming the results, the rats would not open the door if both sides of the box were dry. In fact rats were more likely to open the door if they were cage mates.

Bartal I, Decety J, Mason P. Empathy and Pro-Social Behavior in Rats.  Science 09 Dec 2011; 334 (6061): 1427-1430. DOI: 10.1126/science.1210789

Another good example of research on empathy and “fairness” was a study on crows and ravens. Scientists at University of Vienna trained the birds to trade tokens for food. Once trained, one bird would then have to trade a token for food, while another would get the food for free.

Washcer C & Bugnyar T. Behavioral Responses to Inequity in Reward Distribution and Working Effort in Crows and Ravens. PLOS One. 20 February 2013. DOI: doi.org/10.1371/journal.pone.0056885 

Roughly;