The paleontologist Stephen Jay Gould wrote a book called 'Wonderful Life' about the Cambrian Explosion, when mutlicellular life really got cranking. Basically a

The paleontologist Stephen Jay Gould wrote a book called 'Wonderful Life' about the Cambrian Explosion, when mutlicellular life really got cranking. Basically at that time the ecological slate was clean, and an enormous diversity of organisms developed very quickly. All the expansion of ecological diversity was lateral--essentially green-field evolutionary innovation. Over the next hundred million years or so, the evolutionary innovation was mostly in smaller and smaller tweaks on some evolutionary branches, and the extinction of other branches as they were outcompeted. Never again was there the same wide range of innovation and experimentation--except following expansion into new environments (e.g. when organisms moved onto land) and following mass extinction events. It is really interesting to see how research centers like PARC develop but you're absolutely correct in that it's easier to be creative with a clean slate. Maybe we shouldn't be trying to emulate or reproduce PARC unless we have found a new clean slate somewhere. Instead we should look to where innovation develops particularly rapidly in spite of an establishment.