In essence, in life or death situations, bacteria employ more advanced tactics than those used to solve the classic problem known as "the prisoner's dilemma." This may account for their colony's resilience. In the classic problem, two prisoners are asked to betray each other. If one testifies against the other and the other remains silent, the betrayer goes free and the silent one (the prisoner loyal to his friend), will get 10 years in prison. If both remain silent (and cooperate with each other), they are sentenced to only one year in jail. If each one betrays the other, both will be sentenced to 5 years in jail. The temptation, of course, is to betray but neither prisoner can be sure what the other will say, and could risk five years in jail.
In the case of bacteria, there are not two but hundreds of billions of participants with a limited time to decide whether to deal with a stress situation by all turning into spores. Each bacterium has to decide whether it will cooperate or not. Unlike the prisoners, there is a clock ticking away. And each bacterium must quickly send out chemical messages to its peer cells about its intentions.
Bacteria "usually don't lie" about their own plans, Prof. Ben Jacob says, but the minority that do have a chance of surviving won't cheat to postpone the decision of others. The scientists' new article presents a model that decodes how bacteria use the gene-and-protein networks to calculate risks and the game theory principles they employ.
Maintaining a delicate balance
Americans uncertain about getting the H1N1 flu shot because they've heard about potentially dangerous side effects also face the prisoner's dilemma. Perhaps it's better not to get the shot, one may think, because if everybody else is vaccinated, the virus will be wiped out before it reaches me.
"The simple rule we learned from bacteria is that anybody who has to make an important decision es
|Contact: George Hunka|
American Friends of Tel Aviv University