"The emergent, unplanned city of Hamburg circa 1850, evolved topographically to resemble a human brain. What’s even more interesting is the recent discovery that “brains and cities, as they grow larger, have to be similarly densely interconnected to function optimally.”
Image from Emergence: The Connected Lives of Ants, Brains, Cities and Software by Steven Johnson."
Radiolab has an outstanding primer on emergence here.
What's fascinating to me is that - for all its success - in reducing everything down to the individual, psychology has failed to account for much of human behavior.
Emergence is the study of behaviors that surface only in the context of interconnected groups of individuals, in ways that studying the individuals themselves gives us no clear (and even paradoxical) insight into. This is why psychology is (in an long, evolutionary sense) dying, and sociology is beginning to rise in popularity.
