Quorum sensing as a mechanism to harness the wisdom of the crowds
Bacteria release and sense small molecules called autoinducers (AIs) in a process known as quorum sensing (QS). The prevailing interpretation of QS is that by sensing AI concentrations, bacteria estimate population density to regulate the expression of functions that are only beneficial when carried out by a sufficiently large number of cells. However, a major challenge to this interpretation is that the concentration of AIs strongly depends on the environment, often rendering AI-based estimates of cell density unreliable. Here we propose an alternative interpretation of QS, where bacteria, by releasing and sensing AIs, harness social interactions to sense the environment as a collective. As shown by a model, this functionality can explain the evolution of QS, and results from individuals improving their estimation accuracy by pooling many imperfect estimates - analogous to the wisdom of the crowds in decision theory. Importantly, our model reconciles the observed dependence of QS on both population density and the environment and explains why several QS systems regulate the production of private goods.