Development that lets a system adapt, or grow, from less well adapted to its requirement to more well adapted. Perhaps (straining the metaphor) to be contrasted with UniqueCreationDevelopment. 

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ED would seem to be largely orthogonal to IncrementalDelivery. But EvolutionaryDelivery maybe suggests otherwise (to my muddled early morning brain) --KeithBraithwaite

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See also OrganicSimplicity.