Are you interested in human stigmergy and how it works? 
Our summary today works with the article titled A survey of environments and mechanisms for human-human stigmergy from 2005 by H. Van Dyke Parunak, presented at the Second International Workshop of E4MAS in Utrecht. 
Since we are investigating the future of cities, I thought it would be interesting to see the schema to analyse stigmergy among humans. This article presents the examples and suggests how the use of stigmergy can be extended.
As the most important things, I would like to highlight 3 aspects:

Stigmergy is the notion that an agent’s actions leave signs in the environment, signs that it and other agents sense and that determine their subsequent actions.
Stigmergic systems can generate robust, complex, intelligent behaviour at the system level, even when the individual agents are simple and individually nonintelligent because intelligence resides not in a single distinguished agent, nor in each individual agent but in the interactions among the agents and the shared dynamical environment.
Human stigmergy has been based on non-digital systems, however, with the advent of information technology, it can be advanced with special attention to the highlighted aspects like transparency and simulation.

Abstract: Stigmergy (the coordination of agents through signs they make and sense in a shared environment) was originally articulated in the study of social insects. Its basic processes are much simpler than those usually used to model human-level cognition. Thus it is an attractive way to coordinate agents in engineered environments such as robotics or information processing. Stigmergic coordination is not limited to insects. Humans regularly use environmentally-mediated signals to coordinate their activities. This paper develops a schema for analyzing stigmergy among humans, discusses examples (some using a computational environment and others antedating digital computation), and suggests how the use of such mechanisms may be extended.
You can find the transcript through this link.
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I hope this was an interesting episode for you and thanks for tuning in.
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