What do coral reefs, Italian renaissance city states and Twitter have in common? Steven Johnson's achievement in Where Good Ideas Come From is to establish such connections entirely convincingly.
It used to be said that to talk of technology and culture "evolving" was the loosest kind of metaphor, since the processes have nothing in common. But Johnson shows that human and natural innovation are both heavily dependent on context. The computer could not have come into being before the invention of tiny, multiple transistors; the evolution of cellular life required the prior existence of a chemical self-replicating molecule, and so on. Both processes refashion old parts into new wholes: the art of bricolage.
The parallels Johnson explores between evolution in technology and in the natural world help to explain one of the most persistent problems in evolution by natural selection: that of intermediate forms. If dinosaurs evolved wings and became birds, what drove this forward when the wing was at first tiny and useless? The answer had been staring us in the face and was formally proposed by Stephen Jay Gould and Elizabeth Vrba in 1982: the early "wings" weren't being used as wings at all. When we sleep with eiderdown pillows and duvets, we are using feathers in their original guise: for heat insulation.
Johnson's prime example of a similar technological process is Gutenberg's invention of book printing using moveable type. This breakthrough, which unleashed an acceleration of knowledge and progress, pressed into service the screw devices long used for extracting grape juice for the wine trade.
This process of adapting a structure to a new function was given the name "exaptation" by Gould. It is now a very hot concept in biology because, thanks to the complete genetic sequencing of a fast-growing number of creatures, we can now see how genes as well as bodily organs are put to new uses.
The key to both natural and technological evolution is bricolage – recycling spare parts; taking an object from one context and placing it in another. And the most fertile environments are those that create a platform for innovation, allowing the greatest number of spare part add-ons. This is what unites the coral reef, the Italian city states and Twitter: all are fertile environments that have enabled myriad innovations.