Add a new Rule titled “Unstable Balance” with the following text:

There exists an action called “Check Diversity”.  A Lifeform may occasionally Check Diversity, by posting the text “Check Diversity: (VAR)” to the GNDT, where VAR is the name of an evolutionary variable which has a single number associated with it.
If there are exactly two or three lifeforms with a single value of VAR, each gains X points of Nutrition, where X is eir Complexity.
If there are one or more than four lifeforms with a single value of VAR, each loses X point Nutrition, where X is eir Complexity.