Human Stigmergy Part 1
As far as my explorations have uncovered, little to no research has been done on applying stigmergy to human activity and communication. There have been a few very brief mentions here and there, the most significant in some ways being by Theraulaz & Bonabeau in "A Breif History of Stigmergy" from Artificial Life journal, Volume 5, Issue 2 - Spring 1999, page 102:
Chemical trails that are produced by some ants species [10, 23] muleteer trail networks, and even dirt tracks and trail systems in man [31, 32] result from interactions of this kind.
[31 refers to Modelling the evolution of human trail systems, Dirk Hebling, Joachim Keltsch & Peter Molnar; while 32 refers to Active walker model for the formation of human and animal trail systems, Dirk Helbing, Frank Schweitzer, Joachim Keltsch, Péter Molnár]
Another excellent mention of human stigmergy, although less formal, is in the comment posted by Dylan Shell to Joe Gregorio's great blog post on stigmergy. Here he says:
Another example, perhaps just as old, and even more damaging in some cases, is the process with which people choose illegal dumping grounds. A necessary feature is some degree of seclusion, or at least shelter from the prying eyes of the law. However, we find that once a place has been chosen by some offender, their dump adds a stronger justification to others for that site.