By template reproduction1 we mean a process whereby an offspring is constructed by copying a parent: i.e., the parent serves precisely as a ``template''. The reproductive entity is conceived as some sort of composite system, consisting of a particular configuration or arrangement of components. It must be presumed, of course, that the requisite ``raw materials''--the components to be assembled into the offspring--are available; and the process may or may not rely on some extrinsic ``machinery'' (catalyst) which is not itself reproduced. It is precisely because template reproduction is a copying process that it supports heritable variation: any variation in a parent, howsoever caused, which is recognized and preserved by the particular copying process, will be inherited. For unlimited heredity we require that the class of variant entities that can be faithfully reproduced in this way is indefinitely large. Of course this still allows that there may be many forms of variation that are not heritable (indeed that may cause reproduction to fail altogther).
The practical realisation of template reproduction requires a process that can recognize the individual components of the parent, and their interconnection or configuration; and can then cause matching components to be assembled in a matching configuration. For unlimited heredity, this process must be able to work over an indefinitely large set of distinct parent entities.
Abstractly, we can suppose the set of distinct reproductive variants to be enumerated--i.e., each tagged with an integer identifier. The ``normal'' offspring of any given parent would then be identified with the same tag; variant or mutant offspring would be identified with a different tag. Such numeric tags can be used to apply information theoretic ideas to template reproduction; in particular, one can view the reproductive entity as carrying information, and as communicating or transmitting information to its offspring.
Natural examples of template reproduction with unlimited heredity would be RNA and DNA replication. Some familiar artificial examples would be photocopying, and copying of configurations of various magnetic and optical media (cassette and VCR tapes, computer diskettes, CDs, DVDs etc.).
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