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General Issues of Reproduction

The description of self-reproduction in the definitions of the previous section is stated in terms of the configuration d of object A forcing surrounding S to produce a copy of A. It says nothing of how exactly d can (or should) achieve this feat, although this is a rather fundamental question when comparing different sorts of reproduction. Indeed, when looking at any sort of reproduction, I think it is useful to look at the process by which reproduction is accomplished in (at least) three different ways:
The degree to which the algorithm for reproduction (the way in which the process is specified and controlled) is explicitly encoded on the configuration being reproduced (cf. d in Definition 1), rather than being implicit in the physical laws of the world (cf. S in Definition 1).
Whether reproduction happens purely by the action of the physical laws of the world on the configuration to be reproduced (auto-reproduction), or whether it also requires auxiliary physical (or logical) machinery (assisted-reproduction). I use the term auto-reproduction rather than self-reproduction here because the latter is often used less specifically. I wish to emphasise that this auto-assisted distinction is only one of a variety of issues involved in the general concept of reproduction.
The number of different configurations that exist, connected by mutational pathways, that are capable of reproducing their specific form (i.e. the distinction between limited hereditary reproducers and indefinite hereditary reproducers). From the point of view of an individual reproducer, this can be expressed in terms of the proportion of all possible mutations it may experience that will result in the production of distinct, yet viable, reproducers.

There are a number of points to note about these distinctions. First it should be said that (3), in contrast to (1) and (2), does not properly relate to individual reproducers per se, but rather to lineages of reproducers. It is therefore not relevant when considering self-reproduction in and of itself, but is an important factor when considering the evolutionary potential of a class of reproducers.

Secondly, with regard to distinction (2) in the context of material as opposed to logical systems, I do not consider the fact that objects in material systems need to collect raw materials to be relevant. As long as the surrounding S ordinarily contains sufficient raw materials for a reproducing object A to build a copy of itself, and that the configuration d of A, and the surrounding S between them effect the collection of these materials to build the copy without further assistance, then our definition of self-reproduction given in Section 7.2.1 is still satisfied.

The distinction between auto- and assisted-reproduction is a dichotomy, but the other two distinctions each define a spectrum of possibilities. The distinctions are generally independent of each other, although the more explicitly encoded the reproduction algorithm is, the less likely, in general, it is to be an indefinite hereditary reproducer (because of the increased chance of mutations disrupting the copying process; see Section 7.2.3).

Figure 7.1 shows how some of the reproducers that have been discussed so far can be categorised according to each of these three distinctions. The diagram is not supposed to be quantitatively accurate (not least because the limited-indefinite heredity axis is in fact infinitely long, and also because I have not offered any way of quantifying these factors), but I have tried at least to highlight the general relationships between different types of reproducers according to each of the three distinctions.

Figure 7.1: Categorisation of Reproducers.

There are a number of points about this diagram that require further explanation:

next up previous contents
Next: Self-Reproduction and Open-Ended Evolution Up: Self-Reproduction and Evolution Revisited Previous: Some Definitions
Tim Taylor