The activating fraction a and the dynamics of biochemical networks. The probability the dynamics reach steady state (A) and the average period of oscillation (B) as a function of a. The networks are the Drosophila circadian oscillator (black circle), the Arabidopsis circadian oscillator (blue square) and the NGF signaling network (red diamond). The point corresponding to the natural a is green. The NGF network dynamics typically reach steady state. The circadian network dynamics have a low probability of reaching steady state, but the probability is increased 20-fold when a is high.