Believe it or not,by playing tag, researchers report that gorillas learn about fairness, boundaries and fighting back. For instance, if the gorilla doing the tagging uses just a light touch, it is clearly just a game. But if it is a rough tap, it is a move for being number 1 and not a game at all — unfair! So what is a rough tag and what is a light touch — you got it, boundaries! When you chase, do you give what you got — yepper — fighting back!
Source: Marshall, Michael.(2010, July 14).”Gorillas learn to play fair by playing tag”. New Scientist.