The Existence of Game Theory in a Bacterial Colony
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While microbes and bacteria may not be as intelligent as the humans in the prisoner’s dilemma game theory presented in class, they possess the capability of integrating mathematical reasoning and game theory to determine the best course of action for survival. After studying the soil bacterium Bacillus subtilis in various stressful environments, Jose Onuchic from Rice University realized that this species had the chemical capability of checking how neighbors were responding to the unfavorable environment; two decisions existed for the bacterium of the colony. The first decision is sporulation, or hibernating by dumping half their DNA into the environment and wrapping themselves in a shell. After a period of time or when the conditions have improved, the spore can turn into a regular bacterium again. Nearly 99% of bacteria become spores, but a small percentage choose the second decision of entering a state called competency. During competency, the bacteria choose to forgo sporulation and instead steal some of the neighbor’s discarded DNA to adapt to the harsh environment. Onuchic explained that sporulation is a drastic and traumatic process, and thus it can be advantageous to choose the route of competency as long as the conditions improve. The research shows that these cells make decisions consistent with game theory and mathematical reasoning to determine the best course of action for survival.
This relates to the game theory discussed in CS 2850, and more specifically the prisoner’s dilemma scenario. From a rational perspective, the prisoners should choose to not confess to ensure the consequences are as light for the two as possible. By looking at the situation from the scope of one prisoner, however, defecting becomes the optimal strategy regardless of their partner’s choice. Likewise, the bacteria make decisions not only based on its environment and stress levels, but also by taking into consideration what other bacteria might do. Because sporulation is a 10-hour drastic upheaval, a rational world would dictate that bacteria should always choose to enter competency. However, this is not plausible as the DNA dump would not occur as a result and thus no bacteria can gain the extra DNA to enter the state. Furthermore, an interesting aspect in this scenario was the added element of time constraints and decision timing. Unlike the prisoner’s dilemma in which the first one to act does not face a penalty or reap benefits, the bacterium can prolong their decision and make a more informed judgment based on the percentage of neighbors who entered sporulate. As a result, I can conclude that the game theory optimal strategy for bacterium would be to wait as long as possible for other bacterium to make a decision; the harsher the environment conditions, the sooner my decision should come to avoid death while contemplation. If enough bacterium entered the sporulation state, I could then choose to steal the DNA deposits and enter competency. If a large portion of the bacterium colony decide not to enter sporulation, then I could opt to enter sporulation as the resources available may not suffice a large colony of competent bacterium.