wave said:
How do you define an "accidental genetic variation"? Furthermore, how can you distinguish between, for example, an "accidental" insertion versus a non-accidental insertion? You keep using that phrase but I have no idea what it means...
Well, if that's what is confusing everyone, then I apologize for getting frustrated. Maybe it is my fault for not communicating it better, but I honestly thought the idea was obvious.
Let's start with what convinced Darwin. In his Journal of Researches Darwin commented that, "in the thirteen species of ground-finches, a nearly perfect gradation may be traced from a beak extraordinarily thick to one so fine that it may be compared with that of a warbler. I very much suspect that certain members of the series are confined to different islands."
In this example of genetic variation, it is obvious that within a given species of finch it is natural for bird beak size to vary. That is, a single species may have slightly bigger beaks than average, and single species may contain slightly smaller beaks than average. That variation which causes different size bird beaks within a single species I am saying is "accidental." We know such variation in animals results in different colors and sizes of existing structure. In bacteria we know simple variations to its chemistry allow it to adapt.
One interesting fact is that mutations to complex processing organs such as the liver, heart, eye or brain almost always are harmful or useless. Other examples are how genetic variation in a particular carbon transfer pathway is believed to lead to choline deficiency in humans; genetic variation in copper transporters can lead to Wilson's disease; gene variants have been linked to elevated risks for disorders from Alzheimer's disease to breast cancer.
So in terms of the genetic variation we can observe occurring today in living organisms, there is no indication that mutations will lead to organ development. Yet that is exactly what scientists attribute to mutation!
As Ernst Mayr points out, "Mutation is the ultimate source of all genetic variation found in natural populations and the only new material available for natural selection to work on."
Knowing mutation is what is believed to produce new organs, many scientists have seen a problem with it.
David Metzgar and Christopher Wills pointed out in
Cell, "Adaptive evolution has long been regarded as the result of postmutational sorting by the process of natural selection. Mutations have been postulated to occur at random, producing genetically different individuals that then compete for resources, the result being selection of better adapted genotypes. Molecular biology has demonstrated, however, that the rate and spectrum of mutations is in large part under the control of genetic factors. Because genetic factors are themselves the subject of adaptive evolution, this discovery has brought into question the random nature of mutagenesis. It would be highly adaptive for organisms inhabiting variable environments to modulate mutational dynamics in ways likely to produce necessary adaptive mutations in a timely fashion while limiting the generation of other, probably deleterious, mutations."
Similarly, "The faithful duplication and repair exhibited by the double-stranded DNA structure would seem to be incompatible with the process of evolution. Thus, evolution has been explained by the occurrence of "errors" during DNA replication and repair." Shibata, T., Nishinaka, T., Mikawa, T., Aihara, H., Kurumizaka, H., Yokoyama, S. & Ito, Y. Proc. Natl. Acad. Sci. U.S.A. 98(15) 8425-8432 (2001)
In general genetic mutations result in a net loss of genetic information. There is no naturalistic source for genetic information (nor is there a naturalistic explanation for the existence of information). Genetic mutation simply causes existing genetic information to become corrupted - genetic mutations follow a downward trend. For example, it is universally agreed that wolves, coyotes, dingoes, jackals, foxes, and the hundreds of different domestic dog breeds probably all came from an original pair of "dogs". This is "Variation within a Kind," NOT upward evolution from simplicity into complexity as supposed by Darwin's theory of evolution. The variations are always in a downward trend constrained by the genetic code (the dogs do not grow wings and learn to fly). No new genetic information is added, genetic information is always lost: the original pair of "dogs" had all of the potential characteristics of all their various progeny, while the descendants themselves have lost that same potential.
As the great philosopher Karl Popper pointed out, "The real difficulty of Darwinism is the well-known problem of explaining an evolution which prima facie may look goal-directed, such as that of our eyes, by an incredibly large number of very small steps; for according to Darwinism, each of these steps is the result of a purely accidental mutation. That all these independent accidental mutations should have had survival value is difficult to explain."
Famed geneticist H. Graham Cannon said, "A fact that has been obvious for many years is that Mendelian mutations deal only with changes in existing characters . . . No experiment has produced progeny that show entirely new functioning organs. And yet it is the appearance of new characters in organisms which marks the boundaries of the major steps in the evolutionary scale."
Nobel laureate for penicillin research Ernst Chain said, "To postulate that the development and survival of the fittest is entirely a consequence of chance mutations seems to me a hypothesis based on no evidence and irreconcilable with the facts. These classical evolutionary theories are a gross oversimplification of an immensely complex and intricate mass of facts, and it amazes me that they are swallowed so uncritically and readily, and for such a long time, by so many scientists without a murmur of protest.
Nobel laureate John C. Kendrew for his discovery of the structure of the protein myoglobin said, "Just as in a book misprints are more likely to produce nonsense than better sense, so mutations will almost always be deleterious, almost always, in fact, they will kill the organism or the cell, often at so early a stage in its existence that we do not even realize it ever came into being at all."
Do you see my objection yet? We can strongly support that all life descended from single living source, but we cannot demonstrate that accidental genetic variation produced all the organs/organisms the find present. You can stick your favorite theory where there are evidence gaps, but just because you believe in evolution as presented doesn't give that theory any more credibility than suggesting some sort of universal intelligence has guided genetic variation (when it comes to organ development).