Additional praise for Emergence by Steven Johnson
“It’s easy to see why there aren’t more books like Steven Johnson’s Emergence: Only Johnson knows how to write them… . A tour de force.”
—Harvey Blume, The American Prospect
“A fine new book … brainy but convivial.”
—Erik Davis, The Village Voice
“Thoughtful and lucid and charming and staggeringly smart, all of which I’ve come to expect from Steven Johnson. But it’s also important, I think—a rare, bona fide glimpse of the future.”
—Kurt Andersen, author of Turn of the Century
“A lucid discussion of a fascinating and timely set of ideas.”
—Steven Pinker, professor of psychology, MIT, and author of How the Mind Works and Words and Rules
“Emergence will make understanding ‘emerge’ in your own head, as Steven Johnson explains a lot of phenomena you may not even have noticed.”
—Esther Dyson, author of Release 2.0
“Johnson’s clarity is a boon… . Thought-provoking—and deeply appealing to the inner iconoclast.”
—Kirkus Reviews
“Johnson skillfully weaves together the growth of cities, the organization of protest movements, and the limits and strengths of the human brain.”
—J. G. Ballard, The Daily Telegraph
“Intelligent, witty, and tremendously thought-provoking.”
—Chris Lavers, The Guardian
“Johnson verbalizes what we are beginning to intuit.”
—The Sunday Times (London)
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CONTENTS
New Foreword for the eBook Edition
Introduction: Here Comes Everybody!
PART ONE
Chapter 1: The Myth of the Ant Queen
PART TWO
Chapter 2: Street Level
Chapter 3: The Pattern Match
Chapter 4: Listening to Feedback
Chapter 5: Control Artist
PART THREE
Chapter 6: The Mind Readers
Chapter 7: See What Happens
Notes
Bibliography
Acknowledgments
Index
for my wife
Diagram of the human brain (Courtesy of Mittermeier)
Map of Hamburg, circa 1850 (Courtesy of Princeton Architectural Press)
Most of all, we need to preserve the absolute unpredictability and total improbability of our connected minds. That way we can keep open all the options, as we have in the past.
It would be nice to have better ways of monitoring what we’re up to so that we could recognize change while it is occurring… . Maybe computers can be used to help in this, although I rather doubt it. You can make simulation models of cities, but what you learn is that they seem to be beyond the reach of intelligent analysis… . This is interesting, since a city is the most concentrated aggregation of humans, all exerting whatever influence they can bring to bear. The city seems to have a life of its own. If we cannot understand how this works, we are not likely to get very far with human society at large.
Still, you’d think there would be some way in. Joined together, the great mass of human minds around the earth seems to behave like a coherent, living system. The trouble is that the flow of information is mostly one-way. We are all obsessed by the need to feed information in, as fast as we can, but we lack sensing mechanisms for getting anything much back. I will confess that I have no more sense of what goes on in the mind of mankind than I have for the mind of an ant. Come to think of it, this might be a good place to start.
—LEWIS THOMAS, 1973
New Foreword for the eBook Edition
Emergence is a book about swarms, ant colonies, neighborhoods; a book about crowds and groups—and the intelligence those groups can possess, given the right circumstances. But books themselves are another matter. Yes, there are book groups and public readings, but most of the production and reception of books involves another social architecture, not solitary exactly, but more like a series of one-on-one exchanges: between writer and editor; writer and reader; writer and critic. (Not to mention the one-on-one interviews that are so crucial to a book like this one.) I remember running up against this tension as I was writing Emergence in 2000 and early 2001; here was a book that was a full-throated celebration of the hive mind, but the medium of the book itself—the medium that I most loved, and around which I was beginning to build a career—seemed to belong to a different class: a dialogue between individuals, not a chorus.
But then the book came out, and the world surprised me: the swarm in the story of Emergence the book didn’t manifest until its readers started to do things with it. In the years that followed its publication, I began to hear word of the book’s influence on a wonderfully diverse range of fields and professions: from New Urbanists rebuilding neighborhoods and planning new communities; from city mayors in Brazil creating new models of participatory democracy; from the strategists behind Howard Dean’s groundbreaking use of the Internet to build grassroots support for his presidential run in 2004; from Web entrepreneurs and game designers; from experts in management theory, who had begun to think of supply chains as ant colonies; from artists designing new forms of algorithmic expression that showcased the unpredictable creativity of emergent systems.
There was one other unanticipated twist. The book was published in the United States during the first week of September 2001. Emergence happened to end with a look at the decentralized, swarm-like protest movements that had begun to capture the world’s attention, such as the 1999 anti-WTO protests in Seattle. Then, the week after the book was published, my own city was attacked by a decentralized network of terrorists. Before long I learned that Emergence was being widely read inside the Defense Department and the CIA, as those organizations struggled to adapt to the reality of waging war against networks instead of states.
Emergence was written in the more intimate space of the writer and the reader. But the ideas were ultimately unleashed and reimagined by the crowd. Some of those new applications were more appealing to me than others; some led to genuine breakthroughs, while others turned out to be red herrings or dead ends. But that is the strange truth about all emergent systems: they have a life of their own.
Other books of mine have sold more copies. Others have generated more attention and public debate. But no book of mine has cast such a strange and eclectic shadow of influence. I look forward to watching all the surprising ways in which this new digital version of Emergence will extend that shadow.
Steven Johnson
August 2012
Marin County, California
INTRODUCTION
Here Comes Everybody!
In August of 2000, a Japanese scientist named Toshiyuki Nakagaki announced that he had trained an amoebalike organism called slime mold to find the shortest route through a maze. Nakagaki had placed the mold in a small maze comprising four possible routes and planted pieces of food at two of the exits. Despite its being an incredibly primitive organism (a close relative of ordinary fungi) with no centralized brain whatsoever, the slime mold managed to plot the most efficient route to the food, stretching its body through the maze so that it connected directly to the two food sources. Without any apparent cognitive resources, the slime mold had “solved” the maze puzzle.
For such a simple organism, the slime mold has an impressive intell
ectual pedigree. Nakagaki’s announcement was only the latest in a long chain of investigations into the subtleties of slime mold behavior. For scientists trying to understand systems that use relatively simple components to build higher-level intelligence, the slime mold may someday be seen as the equivalent of the finches and tortoises that Darwin observed on the Galápagos Islands.
How did such a lowly organism come to play such an important scientific role? That story begins in the late sixties in New York City, with a scientist named Evelyn Fox Keller. A Harvard Ph.D. in physics, Keller had written her dissertation on molecular biology, and she had spent some time exploring the nascent field of “nonequilibrium thermodynamics,” which in later years would come to be associated with complexity theory. By 1968, she was working as an associate at Sloan-Kettering in Manhattan, thinking about the application of mathematics to biological problems. Mathematics had played such a tremendous role in expanding our understanding of physics, Keller thought—so perhaps it might also be useful for understanding living systems.
In the spring of 1968, Keller met a visiting scholar named Lee Segel, an applied mathematician who shared her interests. It was Segel who first introduced her to the bizarre conduct of the slime mold, and together they began a series of investigations that would help transform not just our understanding of biological development but also the disparate worlds of brain science, software design, and urban studies.
If you’re reading these words during the summer in a suburban or rural part of the world, chances are somewhere near you a slime mold is growing. Walk through a normally cool, damp section of a forest on a dry and sunny day, or sift through the bark mulch that lies on a garden floor, and you may find a grotesque substance coating a few inches of rotting wood. On first inspection, the reddish orange mass suggests that the neighbor’s dog has eaten something disagreeable, but if you observe the slime mold over several days—or, even better, capture it with time-lapse photography—you’ll discover that it moves, ever so slowly, across the soil. If the weather conditions grow wetter and cooler, you may return to the same spot and find the creature has disappeared altogether. Has it wandered off to some other part of the forest? Or somehow vanished into thin air, like a puddle of water evaporating?
As it turns out, the slime mold (Dictyostelium discoideum) has done something far more mysterious, a trick of biology that had confounded scientists for centuries, before Keller and Segel began their collaboration. The slime mold behavior was so odd, in fact, that understanding it required thinking outside the boundaries of traditional disciplines—which may be why it took a molecular biologist with a physics Ph.D.’s instincts to unravel the slime mold’s mystery. For that is no disappearing act on the garden floor. The slime mold spends much of its life as thousands of distinct single-celled units, each moving separately from its other comrades. Under the right conditions, those myriad cells will coalesce again into a single, larger organism, which then begins its leisurely crawl across the garden floor, consuming rotting leaves and wood as it moves about. When the environment is less hospitable, the slime mold acts as a single organism; when the weather turns cooler and the mold enjoys a large food supply, “it” becomes a “they.” The slime mold oscillates between being a single creature and a swarm.
While slime mold cells are relatively simple, they have attracted a disproportionate amount of attention from a number of different disciplines—embryology, mathematics, computer science—because they display such an intriguing example of coordinated group behavior. Anyone who has ever contemplated the great mystery of human physiology—how do all my cells manage to work so well together?—will find something resonant in the slime mold’s swarm. If we could only figure out how the Dictyostelium pull it off, maybe we would gain some insight on our own baffling togetherness.
“I was at Sloan-Kettering in the biomath department—and it was a very small department,” Keller says today, laughing. While the field of mathematical biology was relatively new in the late sixties, it had a fascinating, if enigmatic, precedent in a then-little-known essay written by Alan Turing, the brilliant English code-breaker from World War II who also helped invent the digital computer. One of Turing’s last published papers, before his death in 1954, had studied the riddle of “morphogenesis”—the capacity of all life-forms to develop ever more baroque bodies out of impossibly simple beginnings. Turing’s paper had focused more on the recurring numerical patterns of flowers, but it demonstrated using mathematical tools how a complex organism could assemble itself without any master planner calling the shots.
“I was thinking about slime mold aggregation as a model for thinking about development, and I came across Turing’s paper,” Keller says now, from her office at MIT. “And I thought: Bingo!”
For some time, researchers had understood that slime cells emitted a common substance called acrasin (also known as cyclic AMP), which was somehow involved in the aggregation process. But until Keller began her investigations, the conventional belief had been that slime mold swarms formed at the command of “pacemaker” cells that ordered the other cells to begin aggregating. In 1962, Harvard’s B. M. Shafer showed how the pacemakers could use cyclic AMP as a signal of sorts to rally the troops; the slime mold generals would release the compounds at the appropriate moments, triggering waves of cyclic AMP that washed through the entire community, as each isolated cell relayed the signal to its neighbors. Slime mold aggregation, in effect, was a giant game of Telephone—but only a few elite cells placed the original call.
It seemed like a perfectly reasonable explanation. We’re naturally predisposed to think in terms of pacemakers, whether we’re talking about fungi, political systems, or our own bodies. Our actions seem governed for the most part by the pacemaker cells in our brains, and for millennia we’ve built elaborate pacemakers cells into our social organizations, whether they come in the form of kings, dictators, or city councilmen. Much of the world around us can be explained in terms of command systems and hierarchies—why should it be any different for the slime molds?
But Shafer’s theory had one small problem: no one could find the pacemakers. While all observers agreed that waves of cyclic AMP did indeed flow through the slime mold community before aggregation, all the cells in the community were effectively interchangeable. None of them possessed any distinguishing characteristics that might elevate them to pacemaker status. Shafer’s theory had presumed the existence of a cellular monarchy commanding the masses, but as it turned out, all slime mold cells were created equal.
For the twenty years that followed the publication of Shafer’s original essay, mycologists assumed that the missing pacemaker cells were a sign of insufficient data, or poorly designed experiments: The generals were there somewhere in the mix, the scholars assumed—they just didn’t know what their uniforms looked like yet. But Keller and Segel took another, more radical approach. Turing’s work on morphogenesis had sketched out a mathematical model wherein simple agents following simple rules could generate amazingly complex structures; perhaps the aggregations of slime mold cells were a real-world example of that behavior. Turing had focused primarily on the interactions between cells in a single organism, but it was perfectly reasonable to assume that the math would work for aggregations of free-floating cells. And so Keller started to think: What if Shafer had it wrong all along? What if the community of slime mold cells were organizing themselves? What if there were no pacemakers?
Keller and Segel’s hunch paid off dramatically. While they lacked the advanced visualization tools of today’s computers, the two scratched out a series of equations using pen and paper, equations that demonstrated how slime cells could trigger aggregation without following a leader, simply by altering the amount of cyclic AMP they released individually, then following trails of the pheromone that they encountered as they wandered through their environment. If the slime cells pumped out enough cyclic AMP, clusters of cells would start to form. Cells would begin following trails created by other cells, cre
ating a positive feedback loop that encouraged more cells to join the cluster. If each solo cell was simply releasing cyclic AMP based on its own local assessment of the general conditions, Keller and Segel argued in a paper published in 1969, then the larger slime mold community might well be able to aggregate based on global changes in the environment—all without a pacemaker cell calling the shots.
“The response was very interesting,” Keller says now. “For anyone who understood applied mathematics, or had any experience in fluid dynamics, this was old hat to them. But to biologists, it didn’t make any sense. I would give seminars to biologists, and they’d say, ‘So? Where’s the founder cell? Where’s the pacemaker?’ It didn’t provide any satisfaction to them whatsoever.” Indeed, the pacemaker hypothesis would continue as the reigning model for another decade, until a series of experiments convincingly proved that the slime mold cells were organizing from below. “It amazes me how difficult it is for people to think in terms of collective phenomenon,” Keller says today.
Thirty years after the two researchers first sketched out their theory on paper, slime mold aggregation is now recognized as a classic case study in bottom-up behavior. Keller’s colleague at MIT Mitch Resnick has even developed a computer simulation of slime mold cells aggregating, allowing students to explore the eerie, invisible hand of self-organization by altering the number of cells in the environment, and the levels of cyclic AMP distributed. First-time users of Resnick’s simulation invariably say that the on-screen images—brilliant clusters of red cells and green pheromone trails—remind them of video games, and in fact the comparison reveals a secret lineage. Some of today’s most popular computer games resemble slime mold cells because they are loosely based on the equations that Keller and Segel formulated by hand in the late sixties. We like to talk about life on earth evolving out of the primordial soup. We could just as easily say that the most interesting digital life on our computer screens today evolved out of the slime mold.
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