  Cooperative search games are collective tasks where all agents share the same
goal of reaching a target in the shortest time while limiting energy
expenditure and avoiding collisions. Here we show that the equations that
characterize the optimal strategy are identical to a long-known
phenomenological model of chemotaxis, the directed motion of microorganisms
guided by chemical cues. Within this analogy, the substance to which searchers
respond acts as the memory over which agents share information about the
environment. The actions of writing, erasing and forgetting are equivalent to
production, consumption and degradation of chemoattractant. The rates at which
these biochemical processes take place are tightly related to the parameters
that characterize the decision-making problem, such as learning rate, costs for
time, control, collisions and their trade-offs, as well as the attitude of
agents toward risk. We establish a dictionary that maps notions from
decision-making theory to biophysical observables in chemotaxis, and vice
versa. Our results offer a fundamental explanation of why search algorithms
that mimic microbial chemotaxis can be very effective and suggest how to
optimize their performance.
