Emergence
From Dar
Steven Johnson suggests that if "...you're building a system designed to learn from the ground level, a system where macrointelligence and adaptability derive from local knowledge, there are five fundamental principles you need to follow...
Johnson's five principles are developed from Deborah Gordon's experiments with harvester ants at Stanford's Gilbert Biological Sciences.
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More is different
This old slogan of complexity theory actually has two meanings that are relevant to our ant colonies. First, the statistical nature of ant interaction demands that there be a critical mass of ants for the colony to make intelligent assessments of its global state. Ten ants roaming across the desert floor will not be able to accurately judge the overall need for foragers or nest builders, but two thousand will do the job admirably. "More is different" also applies to the distinction between micromotives and macrobehaviour: individual ants don't 'know' that they're prioritizing pathways between different food sources when they lay down a pheromone gradient near a pile of nutritious seeds. In fact, if we only studied individual ants in isolation, we'd have no way of knowing that those chemical secretions were part of an overall effort to create a mass distribution line, carrying comparatively huge quantities of food back to the next. It's only by observing the entire system at work that the global behavior becomes apparent.
Ignorance is useful
The simplicity of the ant language - and the relative stupidity of the individual ant - is, as the computer programmers say, a feature not a bug. Emergent systems can grow unwieldy when their component parts become excessively complicated. Better to build a densely interconnected system with simple elements, and let the more sophisticated behaviour trickle up. (That's one reason why computer chips traffic in the streamlined language of zeros and ones). Having individual agents capable of directly assessing the overall state of the system can be a real liability in swarm logic, for the same reason that you don't want one of the neurons in your brain to suddenly become sentient.
Encourage random encounters
Decentralized systems such as ant colonies rely heavily on the random interactions of ants exploring a given space without any predefined orders. Their encounters with other ants are individually arbitrary, but because there are so many individuals in the system, those encounters eventually allow the individuals to gauge and alter the macrostate of the system itself. Without those haphazard encounters, the colony wouldn't be capable of stumbling across new food or of adapting to new environmental conditions.
Look for patterns in the signs
While the ants don't need an extensive vocabulary and are incapable of syntactical formulations, they do rely heavily on patterns in the semiochemicals they detect. A gradient in a pheromone trail leads them toward a food source, while encountering a high ration of nest builders to foragers encourages them to switch tasks. This knack for pattern detection allows meta-information to circulate through the colony mind: signs about signs. Smelling the pheromones of a single forager ant means little, but smelling the pheromones of fifty foragers in the space of an hour imparts information about the global state of the colony.
Pay attention to your neighbours
This may well be the most important lesson that ants have to give us, and the one with the most far-reaching consequences. You can restate it as 'Local information can lead to global wisdom.' The primary mechanism of swarm logic is the interaction between neighboring ants in the field: ants stumbling across each other, or each other's pheromone trails, while patrolling the area around the nest. Adding ants to the overall system will generate more interactions between neighbours and will consequently enable the colony itself to solve problems and regulate itself more effectively. Without neighboring ants stumbling across one another, colonies would be just a senseless assemblage of individual organisms - a swarm without logic."
From Johnson, Steven: 'Emergence', Penguin Books 2001.
Critique: http://www.marxsite.com/emergence.htm
Interview with Johnson: http://www.oreillynet.com/pub/a/network/2002/02/22/johnson.html
Johnson's Blog : http://www.stevenberlinjohnson.com/
Review and exerpt: http://www.simonsays.com/content/book.cfm?sid=33&pid=410896
Finally, here's a link to an article written in January 2005 in which Johnson describes the digital tool he uses for online research.
Tool for thought: http://www.stevenberlinjohnson.com/2005/01/tool_for_though.html#more
