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

[selven]

A rock is a computer 10 billion times more powerful than all of our computers on the planet combined. The hard problem is putting that power to good use,

Re:Thinking Bacteria

[BigSlowTarget]

Bingo, there is some major over generalization going on in this article. The chemical reactions of bacteria to a chemical threat, even honed by millions of years of evolution, are not directly comparable to human reactions to information or threat. Even with billions of members a colony of bacteria has less chemical and informational content than a much smaller number of humans.

"Everyone knows the need to try to postpone important decisions until the last moment but apparently there are simple creatures that do it well and therefore can really teach us -- the bacteria," Really? And if postponing the decision has an impact on the possibility of implementing the selected solution? When a politician delays making a decision he can appear weak and indecisive which is certainly not a benefit - IF he has the data and can make the correct decision earlier. Similarly delaying one decision can have a direct impact on later decisions even when you don't know what those decisions are.

In defense of the article the true value could be in the calculations for weighing the probability of the optimum solution given perfect information that are derived from the bacteria. - a situation never to occur in human history but useful for reference and as a base for future theory.

Re:Thinking Bacteria

[TapeCutter]

The water had no choice, gravity decided for it. Besides the human brian is basically a colony of single celled automata that communicate via chemical messages and perform a sophisticated decision making process (well sometimes anyway).

Re:Bacteria analogous to human beings?

[easyTree]

I'm more interested in how various strategies used by scientists when making the "latest wild claim" (tm) affects their level of success within the game of scientist-gene evolution.

Great Program, Wrong Channel

[DynaSoar]

They've done a bang up job investigating how bacteria adapt, and from the names and departments listed, I can see how they'd be quite able to do so as well as apply it to an expanded game theory scenario.

But applying it to human decision making, strategic or otherwise? Sorry, but they should have included someone on the team from behavioral science that could have pointed out the glaring differences.

They happen on one themselves in saying the bacteria don't lie. The level of stress they're talking about is equivalent to massive drought/starvation. Humans under such conditions do and say all kinds of things, most of it to some degree hiding real intentions.

To extend that, some of human behavior is rational under normal conditions, some isn't (emotionally driven isn't, for instance). With increased stress, less and less is rational. Their very nicely done description of possible decisions at various points based on DNA is entirely rational throughout. Not that the bacteria think, but that the decision is predetermined by being programmed in. There is no irrational result, no off-the-wall craziness drastic behavior resulting in novel solutions. Humans do this. In fact, novel results is a major difference between their work and pretty much any higher organism.

I don't find it particularly instructive that bacteria put off "decision making" until the last moment. As if people don't? It's human nature to constantly refine decisions according to the situation, including attempting top adapt to the situation after a decision has been implemented and the crucial point passed.

The final point they make, where one has to decide based on best guess of others' future behavior, is fairly telling of a major difference between bacteria and humans. Humans can coordinate their decisions so that none obtain an optimal result but all obtain a satisfactory result. That flies in the face of traditional game and economic theory. It also earned John Nash a Nobel. Bacteria can't discuss with predictive insight, they can only wait until the last moment to react.

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.