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. 2012 Sep 6;8(9):e1002669. doi: 10.1371/journal.pcbi.1002669

Figure 3. Evolution towards criticality.

Figure 3

(A) Evolution of the average network sensitivity for four different populations, each initially composed of networks in one of the three dynamical regimes: ordered (Inline graphic, black), critical (Inline graphic, red), and chaotic (Inline graphic, green; and Inline graphic, blue). Under the Darwinian selection given by the ACC and AIC, all the populations quickly become critical (Inline graphic), regardless of their initial dynamical regime. The inset shows that convergence towards criticality occurs during the first 10000 generation steps. The control curves (in light gray) were obtained by evolving populations without selection, and show that the mutagenic method alone drives the networks into the chaotic regime (Inline graphic). (B) Distribution of sensitivities at two different generations for the population that started with Inline graphic chaotic networks. In early generations Inline graphic is quite broad (dashed line), reflecting a great diversity of networks. However, through evolution all the surviving networks approach criticality and the distribution Inline graphic narrows down (solid line). The distribution shown here at generation Inline graphic has Inline graphic.