I might state the "monkey fairness" heuristic as "I deserve at least
as much as X Y and Z do". In the real world, on average, X Y or Z
will just by natural processes seem to be more advantaged in the
narrow way being considered. And X Y and Z use the same strategy, and
may be looking at different aspects of advantage. This provides a
rationale for permanent ratcheting up. The distributions that natural
systems generate are considered unfair by capuchins and humans, which
leads to being pissed off at the world and others a lot of the time.

-dj