Natural Selection and what it didn\'t do for dogs... (Evolution)

by dhw, Sunday, January 24, 2010, 12:04 (5227 days ago) @ David Turell

DAVID: Natural selection is passive, and works only on what variety is offered to it.-For our general discussion on evolution, this remark seems to me so important that I'd like to expand on it, at the risk of repeating earlier arguments. David is echoing Darwin himself: "...variation is a very slow process, and natural selection can do nothing until favourable variations chance to occur" (Difficulties on Theory, p. 202 in my edition of Origin). -This ties in with the definition of natural selection from The New Fontana Dictionary of Modern Thought:-"...The theory asserts that EVOLUTION occurs because those individuals of a SPECIES whose characteristics best fit them for survival are the ones which contribute most offspring to the next generation. These offspring will tend to have the characteristics by virtue of which their parents survived, and in this way the adaptation of the species to its ENVIRONMENT will gradually be improved. It is now generally accepted that natural selection, acting on MUTATIONS which are in their origin non-adaptive, is the primary cause of evolution."-I don't know if others will agree with this definition, but it's a common one, and in my view reflects many of the problems that bedevil discussion of the subject. Not the least is that it begins at the point where we already have different species. As I shall argue in a moment, the title of Darwin's book is misleading, and this definition doesn't help Darwin. In my view, it also glosses over the huge problem raised by David, and if we don't split evolution into its various phases, we lose sight of the extremely restricted capabilities of natural selection. Let's begin with two major elements:-1) Evolution would not be possible without heredity and the ability of organisms to adapt to their environment. These are not CAUSED by natural selection ... they are used by it. 
2) If natural selection acts on mutations, the primary cause is mutations.-Natural selection on its own is incapable of innovation ... it can only select from what is available. Therefore the causes of change are adaptation and mutation. Since we don't know how heredity and adaptability came into being, and mutations are random (and their creative abilities still a matter of debate), only the process of natural selection can be attributed to non-randomness. Small wonder, then, that some materialists prefer to discuss evolution and natural selection as if they were synonymous.-The title On the Origin of Species by Means of Natural Selection is therefore, in my view, way off target. If adaptation to different environments plus mutations account for the changes, the only function of natural selection is to ensure that the adaptations and the beneficial mutations SURVIVE. In which case, natural selection, indispensable though it is to evolution, plays no part in the origin of anything, including species. At most, it brings about improvements in EXISTING organs by preserving the most efficient adaptations.-None of this is an argument against evolution. It's an argument against the constant misuse of the two terms "evolution" and "natural selection", as if the very mention of them were enough to explain a process that we are barely beginning to understand. It's an argument against statements like the following:-"Natural selection [...] is the primary cause of evolution" (Fontana Dictionary).-The Pigliucci anti-design "fallacy", in which by conflating evolution and natural selection he suggests that evolution does not purport to "explain complexity in the biological world by means of random accidents." (I agree with his support of evolution, but I think his argument is false. We need to know how heredity and adaptation originated before we can talk of a fallacy.)-"Natural selection not only explains the whole of life [...]" (Dawkins, God Delusion p. 116 ... the rest of the sentence supplies no qualification of this statement).- "Natural selection: the process which, as far as we know, is the only process ultimately capable of generating complexity out of simplicity" (Dawkins, God Delusion , pp. 150/1... my bold type).-And most famously ... though I can't find it and am quoting from memory: "Darwininian evolution is the creator of life" (Dawkins, website?).-To sum it up: Natural selection does not generate or innovate. It is the fourth and last phase of evolution, following on from heredity, adaptation and mutation, which provide the mechanisms that drive evolution to create new organs, species and complexities. The origin of the first two is unaccounted for, while the third is random. The non-creative, non-random fourth phase only explains survival of what already exists.-
*** Administrative note: We've now got at least three different threads running on this subject, so may I suggest that for the time being we put subsequent evolutionary posts on this one, and supply references to the others when we quote them.