"Swarm Theory"

Part of a much longer article:

Swarm Theory, by Peter Miler, National Geographic: I used to think ants knew what they were doing. ... I just figured they had a plan... How else could ants organize highways, build elaborate nests, stage epic raids, and do all the other things ants do?

Turns out I was wrong. Ants aren't clever little engineers, architects, or warriors after all—at least not as individuals. When it comes to deciding what to do next, most ants don't have a clue. ... Deborah M. Gordon, a biologist at Stanford University. ... [says] "Ants aren't smart, ... Ant colonies are." A colony can solve problems unthinkable for individual ants, such as finding the shortest path to the best food source, allocating workers to different tasks, or defending a territory from neighbors. .... They do it with something called swarm intelligence.

Where this intelligence comes from raises a fundamental question in nature: How do the simple actions of individuals add up to the complex behavior of a group? ...

One key to an ant colony ... is that no one's in charge. No generals command ant warriors. No managers boss ant workers. The queen plays no role except to lay eggs. Even with half a million ants, a colony functions just fine with no management at all—at least none that we would recognize. It relies instead upon countless interactions between individual ants, each of which is following simple rules of thumb. Scientists describe such a system as self-organizing.

Consider the problem of job allocation. In the Arizona desert where Deborah Gordon studies red harvester ants (Pogonomyrmex barbatus), a colony calculates each morning how many workers to send out foraging for food. The number can change, depending on conditions. Have foragers recently discovered a bonanza of tasty seeds? More ants may be needed to haul the bounty home. Was the nest damaged by a storm last night? Additional maintenance workers may be held back to make repairs. An ant might be a nest worker one day, a trash collector the next. But how does a colony make such adjustments if no one's in charge? Gordon has a theory. ...

Before they leave the nest each day, foragers normally wait for early morning patrollers to return. As patrollers enter the nest, they touch antennae briefly with foragers.

"When a forager has contact with a patroller, it's a stimulus for the forager to go out," Gordon says. "But the forager needs several contacts no more than ten seconds apart before it will go out." ...

Foragers use the rate of their encounters with patrollers to tell if it's safe to go out. (If you bump into patrollers at the right rate, it's time to go foraging. If not, better wait. It might be too windy, or there might be a hungry lizard waiting out there.) Once the ants start foraging and bringing back food, other ants join the effort, depending on the rate at which they encounter returning foragers.

"A forager won't come back until it finds something," Gordon says. "The less food there is, the longer it takes the forager to find it and get back. The more food there is, the faster it comes back. So nobody's deciding whether it's a good day to forage. The collective is, but no particular ant is."

That's how swarm intelligence works: simple creatures following simple rules, each one acting on local information. No ant sees the big picture. No ant tells any other ant what to do. ... But the bottom line, says Iain Couzin, a biologist at Oxford and Princeton Universities, is that ... "Even complex behavior may be coordinated by relatively simple interactions," he says.

Inspired by the elegance of this idea, Marco Dorigo, a computer scientist at the Université Libre in Brussels, used his knowledge of ant behavior in 1991 to create mathematical procedures for solving particularly complex human problems ... such as routing trucks...

In Houston, for example, a company named American Air Liquide has been using an ant-based strategy to manage a complex business problem. The company produces industrial and medical gases, mostly nitrogen, oxygen, and hydrogen, at about a hundred locations in the United States and delivers them to 6,000 sites, using pipelines, railcars, and 400 trucks. Deregulated power markets in some regions (the price of electricity changes every 15 minutes in parts of Texas) add yet another layer of complexity. ...

Working with the Bios Group (now NuTech Solutions), a firm that specialized in artificial intelligence, Air Liquide developed a computer model based on algorithms inspired by the foraging behavior of Argentine ants (Linepithema humile)...

For truck drivers, the new system took some getting used to. Instead of delivering gas from the plant closest to a customer, as they used to do, drivers were now asked to pick up shipments from whichever plant was making gas at the lowest delivered price, even if it was farther away.

"You want me to drive a hundred miles? To the drivers, it wasn't intuitive," Harper says. But for the company, the savings have been impressive. "It's huge. It's actually huge."

Other companies also have profited by imitating ants. In Italy and Switzerland, fleets of trucks carrying milk and dairy products, heating oil, and groceries all use ant-foraging rules to find the best routes for deliveries. In England and France, telephone companies have made calls go through faster on their networks by programming messages to deposit virtual pheromones at switching stations, just as ants leave signals for other ants to show them the best trails. ...

When it comes to swarm intelligence, ants aren't the only insects with something useful to teach us. ... [full article]

Comments

[bakho]

Stigmergy was originally discovered and named about fifty years ago by Pierre-Paul Grasse, a biologist studying ants and termites. He was intrigued to learn how these virtually brainless creatures could create highly sophisticated messaging systems and build extremely complex architectural structures. It was a mystifying puzzle that nobody had ever been able to explain.

What he uncovered defied rational explanation. There were no plans, organization or control built into the brains or genes of the ants. The ants weren't even communicating with each other. The sophisticated frameworks and complex structures were emerging spontaneously. The understanding eventually came about through knowledge gained in the study of the self-organizing characteristics of complex systems.

Complexity arises in stigmergic systems because individuals interact not with each other but with a common environment. They interact with the environment by making changes to it. These changes affect the the way further changes are made. This gives rise to a positive feedback effect, where information feeds upon information (much the same effect as when conversations can take unpredictable directions according to the way people respond to each other's comments).

It has only recently been recognized that this concept provides the explanation as to how and why the Internet and the World Wide Web have self-organized to become increasingly more complex.

http://www.stigmergicsystems.com/stig_v1/whatisstigmergy.html?337821

[ken melvin]

How different the brain?

[calmo]

The ascription of intelligence to individuals rather than the groups they belong to or the environment they work in, is over done...much in the same way that dunderheadedness is ascribed to individuals who are kicked out of those groups, groups that can't stand the pain of seeing subpar performance under their otherwise impeccable tutelage.
Now, as bakho says, this (but also, any) thread is a good metaphor of that anthill, making this comment possibly dunderheaded until the next ant (you) come along inspired to make the requisite corrections/addendums/subtendums...
Does this make the ecological system, The Intelligence? What if we blow it all to hell as some fear? [Alright, those dunderheads --paranoid schizophrenics really, just need to be straightened out on what intelligence really is.]

[anne]

The collective sense of viewing insect, or species life, was pioneered by beloved E. O. Wilson in the 1970s, interestingly following on Rachel Carson's reminding us of the science of ecology in the 1950s and 1960s all those years after Charles Darwin or even Ernst Mayr. (I am only wishing to show progression.)

Wilson was wildly criticized for the pioneering field of social-biology, though a continuation from Darwin. In the 1970s the bulk of American philosophers, judged by writings at least, did not understand or care to understand or accept even Darwin. So suggestions that there are commonalities between species including humans were not taken to kindly.

[anne]

What occurs to me in reading this fine article and thinking to the difficulty of getting here from E. O. Wilson, let alone Charles Darwin is how difficult a time we have had in taking biology as a philosophical base, which I often write about. As though biology is always unnerving as we wish to avoid considering who we are.

Then again, economists are quite unwilling to take Kant for a philsophical base as opposed to crude utiltarianism and Kant's philosophy was not biologically based but based on physics. No matter, I appreciate ants and Wilson wrote a wonderous book on ants that won a Pulitzer Prize.

[anne]

http://query.nytimes.com/gst/fullpage.html?res=9C0CEED8173FF93AA15754C0A966958260

July 29, 1990

Consider Their Ways and be Wise
By THOMAS E. LOVEJOY

THE ANTS
By Bert Holldobler and Edward O. Wilson.

Ants are practically everywhere. Only Antarctica, Iceland, Greenland and the part of Polynesia lying east of Tonga lack native ants, but even beyond the kingdom of the ants there are tramp species that have hitchhiked there on human activities. And now comes a book that, while it is intended to be an authoritative account of the study of ants (myrmecology), also makes the intricacies and fascinations of all 8,804 species of the single family (Formicidae) accessible to the average reader. Written in clear, expository English, ''The Ants'' is adorned with excellent illustrations in which the diminutive looms large. The chapter sections taken together could provide a story line in themselves: for example, ''Ant Gardens.'' ''Plants Feed Ants: Food Bodies.'' ''Plants Feed Ants: Extrafloral Nectaries.'' ''Ants Feed Plants: Myrmecotrophy.''

The authors - Bert Holldobler, the Alexander Agassiz Professor of Zoology at Harvard University and a professor of behavioral physiology at the University of Wurzburg in Germany, and Edward O. Wilson, who is the Frank B. Baird Jr. Professor of Science at Harvard and the author of such books as ''On Human Nature'' and ''Sociobiology'' - are world leaders in ant research. Yet they have managed, largely, to avoid a pedantic and suffocating style. While it is impossible to write a definitive tome and make it 100 percent transparent to the nonscientist, this volume achieves the utmost clarity; jargon is kept to a judicious minimum. Its size, weight and price may discourage many people, but I consider it a tremendous bargain.

I once had the privilege of following one of the authors, Mr. Wilson, through a day in a tropical forest. I had thought I knew it well. But our trek was a six-legged revelation: everywhere Mr. Wilson looked he found ants and termites in multitude, as if he had the myrmecological equivalent of the Midas touch. That night we were treated to a spectacle of tiny regiments bearing myriad green banners as a colony of leaf cutter ants engaged in defoliation to provide mulch for a subterranean fungus farm.

Ants indeed remind us of the importance of little things, and of how plants and invertebrates really run our world. They make up in number what they lack in size: one hectare (just under 2.5 acres) of Ivory Coast savannah in Africa holds 7,000 colonies and 20 million individuals. In a high-ground tropical forest ants compose one-third of all the biomass (animal weight). Because harvesting ants cannot carry home with them all the seeds they gather, in New York State ants are estimated to disperse one-third of herbaceous plant species. In tropical forest soils less than one-tenth of one percent of nutrients go below five centimeters, less than two inches. Yet huge leaf cutter ant nests (one nest had 1,000 entrances and 1,027 chambers and produced 38,481 males and 5,339 queens in its third year) are carved to a depth of six meters, almost 20 feet, providing soils near nests an energy and nutrient flow 10 times greater than normal. In New England forests the activity of ants in soil turnover is equal to that of earthworms, and in tropical forests it is even greater.

Ants provide a Lilliputian echo of the diversity of living patterns so generally characteristic of life on earth. Predators, pastoralists and agriculturalists are to be found among the 11 subfamilies. There are ants that harvest wild seed so effectively they compete with rodents. The weaver ants team up in a formicid version of roof raising: ants by the dozen pull the edges of two leaves together until larvae spin silk to sew them together. The Chinese have used weaver ant nests, translocating them to citrus groves, as an effective form of pest control for 1,700 years....

[Alex Tolley]

There is a fascination in simple systems, with few rules, creating apparently optimal system behavior. Whether it is "the invisible hand", "genetic algorithms (and hence evolution) or now "swarm behavior". It is important to realize that while good, these algorithms should not be elevated to almost godlike status as in "the magic of free markets". Ants can create quite good paths for foraging, but, as anyone knows, it is easy to subvert that behavior. Sometimes it pays to think about the system with more than a few simple thought rules.

[calmo]

So its ok for ants to be efficiently organized by the intelligent colony (so intelligent that it has drawn this audience so far...) but we should remember...they B (subvertable) ants and we B men (not quite so subvertable).
Actually Alex you have one of those ambivalent gender tags (like "calmo") [but more like "Pat"] and I get to announce the following on the understanding, (more: insider knowledge)[even more: premium a priori] that you are delightfully female. The shot, possibly not heard round the world yet, is: "Yo the Man!".I cannot resist a good subversion, you?

[Alex Tolley]

calmo - You'd be wrong on my gender. But I think I'm delightfully male (at least to my female friends) and I take it as a compliment that my gender is not obvious from the way I write.

[Harry]

Swarm theory kind of gives basic explanation to how a mob of people behaves and reacts to the environment. Like a large school of fish a rioting mob follows three simple rules.

1. Stick close to next guy.
2. Do exactly as he does.
3. Do not crash into next guy.

The effect of positive feedback is quite obvious in a mob and the murderous destruction just magnified.