Figure 1.

Illustration of the public goods game. (a) The public goods (small brown circles) generated by producers (‘+’ agents in green) are shared unequally between producers and non-producers (‘−’ agents in blue colour). Both producers and non-producers benefit from the presence of the public goods, which promote proliferation or survival of these agents. The public goods can also be supplied from exogenous resources. (b) A zoom-in of the dashed line oval in figure 1a to illustrate the public goods dependent circuit for the producer and non-producer. Coexistence of the two cell types requires feedback (purple line) and unequal sharing of the public goods.