The Silent Cooperator: An Epigenetic Model for Emergence of Altruistic Traits in Biological Systems

Table 3

Notation system.

Notation	Meaning
	Fitness of cell in generation
	Fitness component of cell resulting from PD interactions
	Fitness component of cell resulting from background genes, aggregated as gene X
Gene Y	The trait of taking part in PD interactions; it can be either C, D, or S
C	A variant of gene Y which always expresses cooperative behavior
D	A variant of gene Y which always expresses defector’s behavior
S	A variant of gene Y which expresses cooperative behavior only when triggered by a future state of the environment
	Time, in generations, between appearance of in the population and its activation
Gene X	An abstraction of all genes not taking part in the PD game that contribute to the cell’s fitness
	The increase in the background fitness, , of cell due to a beneficial mutation in the background genes, unrelated to the PD interactions