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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.'"
Maybe someone will update Conway's game of life with these new findings... ..and I'll get a cool new screensaver.
"There is no time, sir, at which ties do not matter," Jeeves, (Jeeves and the Impending Doom)
"Alternately the bacteria may 'choose' to enter a state called competence where they are able to absorb the nutrients from their newly deceased comrades."
The vultures on Wallstreet do this all the time.
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.
Sig Battery depleted. Reverting to safe mode.
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.
That's so easy even I could do it!
First, assume the world's population is an ideal gas in a frictionless vacuum...
Yes because the way that a colony of bacteria reacts is totally similar to how a population of human beings would react.
Are they serious?
Now look here guys, see, I'll spore as soon as each of you spore, but if any one of you display any signs of competence, it's...
So, globally, considering the number of bacteria, could they be the most advanced intelligence? Of course being loosely coupled their time-scale of thought would be extremely slow. They would also exist in a reality very much different than ours.
But then again, once you get inclusive and start using words like "ecosystems" then you can "sum" the "intelligence", everything only has meaning in relation to something else. Together, Earth, is a mind.
Shh.
Very strange - I just finished watching this lecture video this morning. I've all so seen her talk in TED.com
http://microbeworld.libsyn.com/index.php?post_id=516458&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+asm+(MicrobeWorld+Video)#
Cool Stuff!
I'm assuming the longish name is necessary to distinguish it from UCSD's Center for Experimental Biological Physics?
v1... It's called the tragedy of the commons. It is a very old and well-studied phenomenon in game theory.
These scientists really haven't done anything interesting for the game theory community. For their areas, this is outstanding, but for people like myself that work in math and algorithmic game theory, this is hardly a more advanced game that is being played. In particular, imagine multi-agent systems where there are micro-second level decisions that have to be made with much larger strategy profiles being used. Time is definitely being taken into consideration, especially when defending a network from intrusion or other time-sensitive domains.
I'm not really sure, what they want to tell me.
I mean those cells don't have free will and make up decisions up on what's best for their own survival as an individuum.
If there are two populations of bacteria, one with only selfish acting bacteria and one with bacteria that cooperate and where cells even might act unselfish for the greater good and gain an advantage that way over the 1st population, then ofc evolution will prefer the cooperating cells, when the overall reproduction/survival rate of them is just better. Survival of the fittest doesn't necessarily mean survival of the fittest individuum, but survival of the fittest genes. This can also mean survival of those organisms, who perform better,.when organized in a group, so that the group gets an advantage over other groups.
If one looks at ants and bees it's quite obvious. Evolution doesn't care much about the individuum, it just cares that the genetic code is spread most efficiently and it even chooses solutions where thousands of individums don't get any chance for reproduction at all. The bee queen acts as a genetic copy machine and the other animals keep it running and they don't really have a choice then to sacrifice themselves for the greater good, but evolution/math made them that way.
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.
"I may be synthetic, but I'm not stupid." -- Bishop 341-B
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.
As has been said: Asking if machines can think is like asking if submarines can swim. And the answer may not be what you expect.
the optimal solution in a situation like that requires each cell to make probabilistic and independent decisions.
-- I was raised on the command line, bitch
And you? You're giving it to them, *every* which way.
Who's competent and incompetent?
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