Man to the rescue?
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guarantee long-term genetic degeneration. A central theme of this book, if restated, would be that what is already known for clonal populations also applies to sexual populations. The proof that all clonal populations must degenerate genetically was first shown by Muller, and has been termed “Muller’s ratchet” (Muller, 1964; Felsenstein, 1974). Basically, within any clonal line, even the best sub-clones will accumulate mutations over time, and there is no mechanism to “clean house”. Even selection within a clonal line for the best sub-clones, does not stop the decline. The “ratchet” only works one way - all change must be downward. Each cell division adds mutations, and there is no mechanism to take mutations away. Even allowing for some beneficial mutations, each beneficial mutant is always linked, within its sub-clone, to many many more deleterious mutations.
Within clones, there is no mechanism
to break this linkage between rare beneficial mutations and abundant deleterious mutations. The deleterious mutants will always grow in number much faster than the beneficials, and so they will always drag any beneficials down with them. Therefore net information must always decline. To repeat - this applies to even the best, most highly selected sub-clones. The certainty of genomic degeneration in clonal populations is well known among geneticists. The reason there are still many populations of clonal plants (and some animals), appears to reflect the fact that there has not yet been enough time for such populations to degenerate to the point of extinction. Preliminary animal cloning experiments indicate the cloning of animals cannot even produce short-term genetic gains. Cloned animals routinely display immediate and severe genetic damage. Why is this? Cloned animals routinely show evidence of mutational damage - as if they are “pre-aged” (Hochedlinger et al., 2004). There