Stigmergy: The Environment as Memory
Writing with chemistry, reading with antennae
The Term: Stigmergy
Stigmergy was coined by French biologist Pierre-Paul Grasse in 1959, from Greek: stigma (mark) + ergon (work). It means coordination through environmental modification.
The concept predates Gordon, but her work illuminated how it operates at scale.
The Power of Evaporation
Pheromones evaporate. This is crucial. If pheromones were permanent, old information would drown new information.
Evaporation creates automatic information decay. Time encodes relevance. No cleanup algorithm needed.
- Fresh trail = Strong signal = High follow probability
- Aging trail = Weaker signal = Medium probability
- Old trail = Faint signal = Low probability
- Ancient trail = No signal = No response
Environment as Extended Mind
The colony's mind - its memory, decision-making, intelligence - doesn't reside in any ant's brain. It's distributed across pheromone concentrations, tunnel structures, and spatial arrangements.
Remove the ants from their environment, and you've removed their intelligence.
Key Concepts
"Ants have been evolving for more than 100 million years. They've had a long time to perfect their systems of chemical communication. We're just beginning to understand how it works."
Summary
Coordination happens through environmental modification, not message passing. Pheromones serve as external memory, and their natural decay provides automatic information lifecycle management. The environment IS the extended mind of the colony.
Lessons from Ants at Work