A digital ecosystem is a kind of universe, realized in electronic media, in which we observe incremental evolution and complex interaction. The classic examples come from work in Artificial Life, such as Tom Ray'sTierra project in which strings of code compete for resources, such as CPU time, and in which cascades of strategies for success develop, with later ones exploiting the weaknesses and loopholes of their predecessors.
But the idea is much broader. The worldwide web and browser technologies have combined to create a massive digital ecosystem populated by ideas and product descriptions, whose true impact on the human lifestyle is only just beginning to be felt. The human mind was never contained in the head, and has always been a construct involving head, artifacts (such as pen and paper), and webs of communication and interaction. We make our worlds smart so that brains like ours can be dumb in peace. But the development of web and internet technologies may well signal the next great leap in the evolution of thought and reason. For we now have a medium in which ideas can travel, mutate, recombine and propagate with unprecedented ease and (increasingly) across the old barriers of culture, language, geography and central authority.
Moreover, and in a kind of golden loop, we can use our experience with more restricted digital ecosystems to improve our grip on the properties of the kind of large, distributed, self-organizing system of which we are now a proper part. Understanding these properties is important both for policy making (what kind of regulation creates and maintains the optimal conditions for productive self-organization in a complex and highly uncertain world?) and for moral and economic reason. Human brains are bad at seeing the patterns that will result from multiple, ongoing, bidirectional interactions: see, for example, the simulations that show, to most peoples surprise, that if each person in a group insists on having just 30% of their neighbors 'the same' as them (picked out by race, gender, sexual inclination or whatever you like), that over a short period of time what evolves is a highly segregated ecology containing a great many 'all X' neighborhoods. Perhaps if our children get to play with quite large-scale digital ecosystems, in games such as Sim City or using new educational resources such as such as Mitchell Resnick's Starlogo, they may yet learn something of how to predict, understand, and sometimes avoid, such emergent patterns.
Digital ecosystems thus both radically transform the space in which human brains think and reason, and provide opportunities to help us learn to reason betterabout the kind of complex system of which we are now a part. The double-whammy gets my vote.