Editor's note: TED is a nonprofit organization devoted to "Ideas worth spreading," which it makes available through talks posted on its website. Steven Berlin Johnson is the author of "Where Good Ideas Come From: The Natural History of Innovation."
(CNN) -- Amazon, Google, eBay, YouTube, Facebook, Twitter -- we've all experienced firsthand the innovative power of the Web's global network.
No medium in the history of communications has transformed itself with such blistering speed. But the pattern of an open, densely connected network leading to breakthrough innovation turns out to have deep roots -- roots that extend back to the beginnings of human civilization.
The computer scientist Christopher Langton observed several decades ago that innovative systems have a tendency to gravitate toward the "edge of chaos:" the fertile zone between too much order and too much anarchy.
Langton sometimes uses the metaphor of different phases of matter -- gas, liquid, solid -- to describe these network states. Think of the behavior of molecules in each of these three conditions.
In a gas, chaos rules; new configurations are possible, but they are constantly being disrupted and torn apart by the volatile nature of the environment. In a solid, the opposite happens: The patterns have stability, but they are incapable of change. But a liquid network creates a more promising environment for the system to explore the adjacent possible.
New configurations can emerge through random connections formed between molecules, but the system isn't so wildly unstable that it instantly destroys its new creations.
You can see Langton's observation at work in the history of human culture. For ages, early humans lived in the cultural equivalent of gaseous networks: small packs of hunter-gatherers bouncing around the landscape, with almost no contact between groups. But the rise of agriculture changed all that. For the first time, humans began forming groups that numbered in the thousands, or tens of thousands.
After millennia living in an intimate cluster of extended family, they began sharing a space crowded with strangers.
With that increase in population came a crucial increase in the number of possible connections that could be formed within the group. Good ideas could more readily find their way into other brains and take root there. New forms of collaboration became possible.
What happened when they began forming these liquid networks? An explosion of innovation. Within a few millennia of the first cities being founded, an astonishing number of crucial inventions entered the historical record: alphabets, currency, sewers, aqueducts, soap, furnaces.
The rate of innovation in urban centers is an order of magnitude faster than in pre-urban life. When you look at the past from this perspective, one thing becomes clear: Somewhere within a thousand years of the first cities emerging, humans beings invented a whole new way of inventing.
No doubt some ingenious hunter-gatherer stumbled across the cleansing properties of soap, or dreamed of building aqueducts, in those long eons before the rise of cities, and we simply have no record of his epiphany. But the lack of a record is exactly the point.
In a low-density, chaotic network, ideas come and go. In a dense network like those of the first cities, good ideas have a natural propensity to get into circulation. They spill over, and through that spilling they are preserved for future generations. For reasons we will see, high-density liquid networks make it easier for innovation to happen, but they also serve the essential function of storing those innovations. Before writing, before books, before Wikipedia, the liquid network of cities preserved the accumulated wisdom of human culture.
The pattern repeated in the explosion of commercial and artistic innovation that emerged in the densely settled hill towns of Northern Italy, the birthplace of the European Renaissance. Once again, the rise of urban networks triggered a dramatic increase in the flow of good ideas. It is not a coincidence that Northern Italy was the most urbanized region in all of Europe during the 14th and 15th centuries.
A society organized around urban marketplaces, instead of castles or cloisters, distributes decision-making authority across a much larger network of individual minds. The innovation power of the marketplace derives, in part, from this most elemental math: No matter how smart the "authorities" may be, if they are outnumbered a thousand to one by the marketplace, there will be more good ideas lurking in the market than in the feudal castle.
Cities and markets recruit more minds into the collective project of generating good ideas. As long as there is spillover between those minds, useful innovations will be more likely to appear and spread through the population at large.
In thinking about networked innovation this way, I am specifically not talking about a "global brain" or a "hive mind." There are indeed some problems that are wonderfully solved by collective thinking: the formation of neighborhoods in cities, the variable signals of market pricing, the elaborate engineering feats of the social insects. But as many critics have pointed out -- most recently, the computer scientist and musician Jaron Lanier -- large collectives are rarely capable of true creativity or innovation. (We have the term "herd mentality" for a reason.)
When the first market towns emerged in Italy, they didn't magically create some higher-level group consciousness. They simply widened the pool of minds that could come up with and share good ideas. This is not the wisdom of the crowd, but the wisdom of someone in the crowd. It's not that the network itself is smart; it's that the individuals get smarter because they're connected to the network.
The opinions expressed in this commentary are solely those of Steven Berlin Johnson.