Open-Ended Evolution.

This term refers to a system in which components continue to evolve new forms continuously, rather than grinding to a halt when some sort of `optimal' or stable position is reached. In other words, using the terminology just introduced, new, adaptively successful, S-lineages are continuously appearing and displacing existing S-lineages. Note that open-ended evolution does not necessarily imply any sort of evolutionary progress. Also note that this is still not a perfect definition; there are some more subtle issues involved in determining what counts as `new' in this context. Also, by using the term `open-ended' I wish to imply that an indefinite variety of phenotypes are attainable through the evolutionary process, rather than continuous change being achieved by, for example, cycling through a finite set of possible forms. I will return to some of these issues in Chapter 7 (for example, in Sections 7.1.2 and 7.3.2).