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Bacterial Prisoner's Dilemma and Game Theory
dumuzi writes "Scientists studying how bacteria under stress collectively weigh and initiate different survival strategies say they have gained new insights into how humans make strategic decisions that affect their health, wealth and the fate of others in society. The authors of the new study are theoretical physicists and chemists at the University of California, San Diego's Center for Theoretical Biological Physics. In nature, bacteria live in large colonies whose numbers may reach up to 100 times the number of people on earth. Many bacteria respond to extreme stress — such as starvation, poisoning and irradiation — by creating spores. Alternately the bacteria may 'choose' to enter a state called competence where they are able to absorb the nutrients from their newly deceased comrades. 'Each bacterium in the colony communicates via chemical messages and performs a sophisticated decision making process using a specialized network of genes and proteins. Modeling this complex interplay of genes and proteins by the bacteria enabled the scientists to assess the pros and cons of different choices in game theory. It pays for the individual cell to take the risk and escape into competence only if it notices that the majority of the cells decide to sporulate,' explained Onuchic. 'But if this is the case, it should not take this chance because most of the other cells might reach the same conclusion and escape from sporulation.'"
a case of where the individuals are all trying to make decisions that are selfish, but if everyone is selfish, no one wins, so some have to be selfish and some have to fold, for any to survive. I seem to remember playing games like that as a kid, where it was basically a game of chicken, where no one could do anything until everyone was generous, and so everyone then starts building up, and whoever managed to switch back to greedy first won. Also reminiscent of the stock market during a bubble, eh?
I work for the Department of Redundancy Department.
Obviously the bacteria aren't "thinking" in any way that could usefully be crammed into the usual definition of the word; but I don't think that either "sophisticated" or "decision" are being distorted at all.
It is quite common, for instance, to refer machines that have a fair number of parts and are good at what they do as "sophisticated"("a sophisticated inertial navigation mechanism"). Even unicellular procaryotes have a fair amount going on inside, so they could easily fall under this definition.
As for "decision", that certainly can imply a process of rational, reflective cogitation; but it is also quite commonly applied to fairly simple, entirely mechanistic, things. "Decision Algorithms", for instance, are explicitly designed to be mechanistic and, as their name suggests, make decisions. The idea that the process whereby a cell enters either stateA or stateB depending on certain inputs is a "decision process" seems wholly reasonable to me.
They are - and for good reason. Game theory has been very successful in understanding some of the basic trade-offs involved in individual vs group decision-making. Certain set-ups such as the http://en.wikipedia.org/wiki/Prisoners_dilemma are generic forms of common problems that are encountered both in the human world and the natural world. Having worked in this area I can tell you that solutions found in the natural world often end up as inspiration for real life applications - such as regulation of industry and organisational psychology. At the end of the day one of the most re-occurring problems is how to get selfish people to co-operate as a group - and this problem has been solved so many times by nature in so many ways its basically a handy repository of tried and true solutions just waiting to be discovered.
Control is an illusion, order our comforting lie. From chaos, through chaos, into chaos we fly