Here's another in a series of responses to some common assertions/misunderstandings of evolutionary biology by creationists and "intelligent design" supporters. One of the most common arguments against the theory of evolution is that natural selection cannot produce genuinely new information:
"Natural selection does not produce new information. On the contrary, it only reduces existing genetic information. Evolutionary biologists shouldn't invoke mutations as a source of new information, because all known mutations involve a net loss of information."
This viewpoint demonstrates a basic misunderstanding of the process of evolution bynatural selection. According to Darwin (and virtually all evolutionary biologists), natural selection has three prerequisites:
1) Variety, generated by the "engines of variation";
2) Heredity, mediated by the transfer of genetic material (either vertically - from parents to offspring - or horizontally - via viral transduction, retrotranscription, etc.); and
3) Fecundity, that is, reproduction, usually at a rate that exceeds replacement (according to Malthus).
Given these three prerequisites, the following outcome is virtually inevitable:
4) Demography: Some individuals survive and reproduce more often than others. Ergo, the heritable variations of such individuals become more common over time in populations of those organisms.
Natural selection is synonymous with #4; it is an outcome of the three processes listed as prerequisites, not a "mechanism" in and of itself.
Ergo, the real dispute between evolutionary biologists and "intelligent design" supporters is not over natural selection per se, but rather the properties and capabilities of the "engines of variation". I have written extensively about these here and here.
Yes, natural selection (i.e. #4, above) is conservative not creative. It produces no new genetic nor phenotypic information, which is why Darwin eventually came to prefer the term "natural preservation" rather than "natural selection". However, it is also clear that the "engines of variation" - that is, the processes the produce phenotypic variation among the members of populations of living organisms - are both extraordinarily creative and extraordinarily fecund. The real problem in biology is therefore not producing new variation, but rather limiting the production of new variation to the point that the "engines of variation" do not cause the inevitable disintegration of living systems.
As just one example of this problem, the genetic elements known as transposons generate a huge amount of new genetic variation, much of which is either phenotypically neutral or deleterious to the organism. There are biochemical mechanisms by which cells can monitor the incidence of transposition in themselves, and limit its consequences (up to and including the active self-destruction of the cell via apoptosis).
At the same time, there is very good evidence in the genomes of many organisms that retrotransposition events mediated by transposons have occasionally produced genetic changes that have resulted in increased survival and reproduction of the organisms in which such events have taken place. There is a large and growing literature on this phenomenon, all of which points to the inference that retrotransposition via transposons both creates new genetic and phenotypic variation, and that in some cases such variation can provide the raw material for evolutionary adaptations, which are preserved via natural selection.
So, if someone really wants to find out where the Intelligent Designer might create new variations, they should follow the lead of Darwin's good friend, Asa Gray, and look for the telltale evidence (if any) for such intervention in the "engines of variation". Of course, they would have to show pretty conclusively (using empirical investigations and statistical analysis) that such "creation events" are not the result of purely natural, unguided processes. If they can do this, they will undoubtedly win a Nobel Prize and a Crafoord Prize (plus a MacArthur or two).
Notice that this will involve looking carefully into the mechanisms by which new variations are produced, rather than pointing to the outcomes of such processes (i.e. natural selection) and simply asserting that "you can't get here from there". Simply asserting (without empirical evidence) that something can't happen isn't "doing science" at all. In fact, it's doing just the opposite...
...it's doing ID the way it's always been done up until now; by press release, rather than by empirical research.
As always, comments, criticisms, and suggestions are warmly welcomed!
--Allen