Marcel, a mechanical chessplayer... his exquisite 19th-century brainwork --- the human art it took to build which has been flat lost, lost as the dodo bird ... But where inside Marcel is the midget Grandmaster, the little Johann Allgeier? where's the pantograph, and the magnets? Nowhere. Marcel really is a mechanical chessplayer. No fakery inside to give him any touch of humanity at all.
--- Thomas Pynchon, Gravity's Rainbow .
The objective of the approach discussed here, is to create an instantiation of evolution by natural selection in the computational medium. This creates a conceptual problem that requires considerable art to solve: ideas and techniques must be learned by studying organic evolution, and then applied to the generation of evolution in a digital medium, without forcing the digital medium into an "un-natural" simulation of the organic world.
We must derive inspiration from observations of organic life, but we must never lose sight of the fact that the new instantiation is not organic, and may differ in many fundamental ways. For example, organic life inhabits a Euclidean space, however computer memory is not a Euclidean space.
Intra and inter-cellular communication in the organic world is chemical in nature, in which chemical messages diffuse through the system and cause changes in shapes of receptor molecules leading to a cascade of effects. By contrast, communication in digital computers generally involves the targeted transfer of bit patterns, which can carry arbitrary amounts of information. The receiving end then must interpret the data. While we may see analogies between these two kinds of communications, they are fundamentally different and can be most effectively untilized through completely different information processing mechanisms.
The fundamental principal of the approach being advocated here is to understand and respect the natural form of the digital computer, to facilitate the process of evolution in generating forms that are adapted to the computational medium, and to let evolution find forms and processes that naturally exploit the possibilities inherent in the medium.
Situations arise where it is necessary to make significant changes from the standard computer architecture. But such changes should be made with caution, and only when there is some feature of standard computer architectures which clearly inhibits the desired processes. Examples of such changes are discussed in the section "The Genetic Language" below. Less substantial changes are also discussed in the sections on the "Flaw" genetic operator, "Mutations", and "Artificial Death". The sections on "Spatial Topology" and "Digital `Neural Networks' --- Natural AI" are little tirades against examples of what I consider to be un-natural transfers of forms from the natural world to the digital medium.