Amendable decisions in living systems

Abstract

A distinct feature of living systems is their capacity to take decisions based on uncertain environmental signals. Examples span from the microscopic scale of cell differentiation guided by the concentration of a morphogen, to complex choices made by animals and humans. The current paradigm in decision theory assumes that decisions, once taken, cannot be revoked. However, living systems often amend their decisions if new evidence favors an alternative hypothesis. In this paper, we characterize the optimal strategy for such amendable decisions. We find that, unlike irrevocable decisions, optimal amendable decisions can be made in a finite average time with zero error probability. Our theory successfully predicts the outcome of a visual experiment involving human participants and the accuracy of cell-fate decisions in early development. We also present possible implementations of amendable decision-making by means of either biochemical reactions or transcription regulation. Our study reveals that amendments lead to a substantial advantage in decision making, that is likely to be widely exploited by living beings.