A great deal more work is required before we can properly understand the evolutionary consequences of design decisions relating to each of these more specific issues. Von Neumann's architecture was designed specifically so that the self-reproducing automata would have the potential of participating in an evolutionary process in which more and more complicated automata arose. I am not aware of such a detailed analysis of other sorts of reproduction, although it has been suggested that collectively-autocatalytic sets generally do not have great evolutionary potential (see, for example, [Maynard Smith & Szathmáry 95]). It has also been suggested that reproduction by self-inspection (discussed on p.) has less evolutionary potential than genetic reproduction (e.g. [von Neumann 66] pp.121-123, [McMullin 92a] pp.191-193), although little has actually been proved.
For truly open-ended evolution, we might also want to consider how one sort of reproduction might evolve from another sort.3.29 I will return to discuss these issues in much more detail in Chapter 7, with the benefit of experience gained from running an extensive series of experiments with a Tierra-like platform (reported in Chapters 4-6). The main point I wish to make here is that the evolvability of the system clearly does depend upon the type of reproduction employed, and upon other issues involved in the concept of self-reproduction, even if we do not yet fully understand these dependencies.