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.'"

Comments

Thinking Bacteria

[icebike]

Each bacterium in the colony communicates via chemical messages and performs a sophisticated decision making process...

I'm sorry, but that stretches the meaning of "sophisticated" and "decision" beyond all reason.

One might just as well argue that water flowing down hill has made a sophisticated decision.

Re:Thinking Bacteria

[fuzzyfuzzyfungus]

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.

Re:Thinking Bacteria

[Anonymous Coward]

> A rock is a computer 10 billion times more powerful than all of our computers on the planet combined.

Is that including the other rocks?

strategy sounds familiar

[v1]

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?

Re:strategy sounds familiar

[TubeSteak]

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?

Stock markets do not allow for equal access to information.
That inequality seriously skews any game theory in favor of the well connected.

Re:Bah. nothing new

[Calydor]

I'm pretty sure none of the Wall Street vultures have EVER entered a state called 'competence'.

NOT a prisoner's dilemma

[Main Gauche]

Why is it that anyone who's learned the slightest bit of game theory suddenly thinks everything is a Prisoner's Dilemma?

In a (1-shot) Prisoner's Dilemma, one action is always better for you than another, leaving little to analyze.

In the Bacteria's game, the bacteria are obviously programmed to do what is best to ensure the survival of the species. (FTFA: "bacteria usually do not cheat their friends and inform them by sending chemical messages about their true intensions.") Whether a bacterium should spore or not depends on the proportion of other bacteria doing each action. This is not the structure of a P.D. It's one thing for journalists to make a bad reference, but the physicist himself refers to Prisoner's Dilemma.

Re:Bacteria analogous to human beings?

[Cassius Corodes]

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.