Are ideas of justice and equality only human traits? Do these rise out of a Platonic soul deep within our being? Or are these biological traits?
There is evidence that this is indeed dictated by our biology. In this experiment, two monkeys are taught a trade system, rock for food, and this trade works fine with a cucumber, until the second monkey receives a better trade (a grape) which causes the first to become upset about the injustice.
Click here to see the video (starts at 13 minute mark):