Tuesday, July 10, 2007

Swarm intelligence and real-world problem-solving

From BoingBoing:

National Geographic has a terrific article covering the state of the art in the use of simulated swarming/flocking/schooling as a means of solving hard technical and social problems, from planning meetings to routing Southwest Airlines's cargo to creating realistic CGI.

I love this stuff. There's such elegance in using simulated hives to let computers evolve surprising, counter-intuitive and highly effective solutions to our problems. I took a stab at exploring the social consequences of this in my story Human Readable, where simulated ant-colonies are used to allocate all of humanity's resources.

I just finished reading a killer novel that goes way farther down this road. Chris Moriarty's Spin Control concerns itself with the clash of civilizations between hive-like, genetically engineered, ant-obsessed clones and the remaining baseline humans, after the Earth has been razed by climate change. Moriarty included an impressive and exhaustive bibliography at the end of the book that had me drooling and wishing for another eight hours in the day, just so I could read half the books on it. (Moriarty also has a good collection of links on the subject).

"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."

To see how this works, Gordon and her collaborator Michael Greene of the University of Colorado at Denver captured patroller ants as they left a nest one morning. After waiting half an hour, they simulated the ants' return by dropping glass beads into the nest entrance at regular intervals—some coated with patroller scent, some with maintenance worker scent, some with no scent. Only the beads coated with patroller scent stimulated foragers to leave the nest. Their conclusion: 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."

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