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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 3 of 3. This is the beginning of the thread.
Posted by alexandra_k on March 10, 2005, at 1:25:49
Why do people cluster together in neighbourhoods?
How do internet communities spring up from nowhere?
Why is a brain conscious even though no single neuron is?The answer, as Steven Johnson's groundbreaking book shows, is emergence: change that occurs from the bottom up. When enough individual elements interact and organize themselves, the result is collective intelligence - even though no one is in charge. It is a phenomenon that exists at every level of experience, and will revolutionize the way we see the world.
(From the bit off the back cover).An excerpt:
HERE COMES EVERYBODY
In August of 2000, a Japanese scientist named Toshiyuki Nakagaki announced that he had trained an amoebalike organism called slime mold to find the shortest route through a maze. Nakagaki had placed the mold in a small maze comprising four possible routes and planted pieces of food at two of the exits. Despite its being an incredibly primitive organism (a close relative of the ordinary fungi) with no centralised brain whatsoever, the slime mold managed to plot the most efficient route to the food, stretching its body through the maze so that it connected directlly to the two food sources. Without any apparent cognitive resources, the slime had 'solved' the maze puzzle...
If you are reading these words during the summer in a suburban or rural part of the world, chances are somewhere near you a slime mold is growing. Walk through a normally cool, damp section of a forest on a dry and sunny day, or sift through the bark mulch that lies on a garden floor, and you may find a grotesque substance coating a few inches of rotting wood. On first inspection, the reddish orange mass suggests that the neighbours dog has eaten something disagreeable, but if you observe the slime mold over several days - or, even better, capture it with time-lapse photography - you'll discover that it moves, ever so slowly, across the soil. If the weather conditions grow wetter and cooler, you may return to the same spot and find the creature has disappeared altogether. Has it wandered off to some other part of the forest? Or somehow vanished into thin air, like a puddle of water evaporating?
As it turns out, the slime mold (Dictyostelium discoideum) has done something far more mysterious, a trick of biology that had confounded scientists for cenruries... For that is no disappearing act on the garden floor. The slime mold spends much of its life as thousands of distinct single - celled units, each moving seperately from its other comrades. Under the right conditions, those myriad cells will coalesce again into a single, larger organism, which then begins its leisurely crawl across the garden floor, consuming rotting leaves and wood as it moves about. When the environment is less hospitable, the slime mold acts as a single organism; when the weather turns cooler and the mold enjoys a large food supply, : "it" becomes a "they". The slime mold oscillates between being a single creature and a swarm.
While slime mold cells are relatively simple, they have attracted a disproportionate amount of attention from a number of different disciplines - embryology, mathematics, computer science - because they display such an intriguing example of coordinated group behaviour. Anyone who has ever contemplated the great mystery of human physiology - how do all my cells manage to work so well together? - will find something resonant in the slime molds swarm. If only we could figure out how the Dictyostelium pull it off, maybe we would gain some insight into our own baffling togetherness...
For some time, researchers had understood that slime cells emitted a common substance called acrasin (also known as cyclic AMP), which was somehow involved in the aggregation process. But until Keller began her investigations, the conventional belief had been that slime mold swarms formed at that command of "pace-maker" cells [homunculi] that ordered the other cells to begin aggregating. In 1962, Harvard's M. B. Shafer showed how the pacemakers could use cyclic AMP as a sort of signal to rally the troops; the slime mold generals would release the compounds at the appropriate moments, triggering waves of cyclic AMP that washed through the neighbours. Slime mold aggregation, in effect, was a giant game of Telephone - but only a few cells placed the original call.
It seemed like a perfectly reasonable explanation. We're naturally predisposed to think in terms of pacemakers, whether we're talking about fungi, political systems, or our own bodies. Our actions seem governed for the most part by the pacemaker cells in our brains, and for millennia we've built elaborate pacemaker cells into our social organizations, whether they come in the form of kings, dictators, or city councilmen. Much of the world around us can be explained in terms of command systems and hierarchies - why should it be any different for the slime molds?
But Shafer's theory had one small problem: no one could find the pacemakers. While all observers agreed that waves of cyclic AMP did indeed flow through the slime mold community before aggregation, all the cells in the community were effectively interchangable. None of them possessed any indistinguishing characteristics that might elevate them to pacemaker status. Shafer's theory had presumed the existence of a cellular monarchy commanding the masses, but as it turned out, all slime mold cells were created equal.
For the next twenty years that followed the publication of Shafer's original essay, mycologists assumed that the missing pacemaker cells were a sign of insufficient data, or poorly designed experiements: The generals were there somewhere in the mix, the scholars assumed - they just didn't know what their uniforms looked like yet. But Keller and Segal took another, more radical approach. Turing's work on morphogenesis had sketched out a mathematical model wherein simple agents following simple rules could generate amazingly complex social structures; perhaps the aggregations of slime mold cells were a real-world example of that behaviour. Turing had focused primarily on the interaction between cells in a single organism, but it was perfectly reasonable to assume that the math would work for aggregarions of free-floating cells. And so Keller started to think: What if Shafer had it wrong all along? What if the community of slime mold cells were organizing themselves? What if there were no pacemakers?
Keller and Segal's hunch paid off dramatically. While they lacked the advanced visualisation tools of todays computers, the two scratched out a series of equations using pen and paper, equations that demonstrated how slime cells could trigger aggregation without following a leader, simply by altering the ammount of cyclic AMP they released individually, then following trails of the pheromone that they encountered as they wandered through their environment. If the slime cells pumped out enough cuclic AMP, clusters of cells would start to form. Calls woul dbegin following trails created by other cells, creating a positive feedback loop that encouraged more cells to join the cluster. If each solo cell was simply releasing cyclic AMP based on its own local assessment of the general conditions, Keller and Segal argued in a paper published in 1969, then the slime mold community might be well abel to aggregate based on global changes in the environment - all without a pacemaker cell calling the shots...
Thirty years after the two researchers first sketched out their theory on paper, slime mold aggregation is now recognized as a classic study in bottom up behaviour. Keller's colleague at MIT Mitch Resnick has even developed a computer simulation of slime mold cells aggregating, allowing students to explore the eerie, invisible hand of self-organization by altering the numbers of cells in the environment, and the levels of cyclic AMP distributed. First time users of Resnick's simulation invariably say that the on-screen images - brilliant clusters of red cells and green pheromone trails - remind them of video games, and in fact the comparison reveals a secret lineage. Some of today's most popular computer games resemble slime mold cells because they are loosely based on the equations that Keller and Segal formulated by hand in the late sixties.
We like to talk about life on earth evolving out of the primordial soup. We could just as easily say that the most interesing digital life on our computer screens today evolved out of slime mold.
Hmm. What if we substitute 'posts' for 'AMP'...
"Emergence" Steven Johnson pp. 11-17
Posted by alexandra_k on March 10, 2005, at 1:26:50
In reply to Emergence, posted by alexandra_k on March 10, 2005, at 1:25:49
Posted by Damos on March 13, 2005, at 15:34:07
In reply to Re: And now for the correct link..., posted by alexandra_k on March 10, 2005, at 1:26:50
Thankyou so much for this and your many other posts that mean I'll probably need to take a decade off to read all the things you've sparked and reignited my interest in. This one's particularly facinating.
Hmmm, posts instead of AMP? I think in many cases our posts do cause connectedness to emerge, and that this is because individual posts trigger a [compassion] receptor within us that causes us to respond to that message and connect with the author. These are recognised by the emotion that simply pours from the words on the screen and where the self becomes a secondardy consideration.
Other forms of post do in fact have a pace-maker. Usually you it would appear :-) People come together but in a slightly different way, an exciting, stimulating and engaging way but a way in which each individual still holds on to their own opinion and individual position. There is sometimes convergence toward a better and more common understanding.
I guess you could say that I believe that the existence of emergence in people is an absolute fact.
Thanks again alexandra_k
This is the end of the thread.
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Dr. Bob is Robert Hsiung, MD,
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