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Mutations and Natural Selection
What Can They Accomplish for Evolution?²⁴

The observed occurrence of mutations spontaneously in nature is used as evidence for the theory of evolution. Since 1928 the process of mutation has been investigated through the use of ionizing radiation which greatly increases the rate of appearance of mutations. Dr. H.J. Muller first made the discovery of the possibility through his work with fruit flies. However, the realization that most mutations were harmful to the species made scientists cautious, unwilling for the most part to make great claims for the advantages of mutations as a source of variations in a population, the variations upon which, according to Darwinian theory, natural selections could act to bring about the origination of new varieties by evolution.

It was shown, for example, that a one-percent advantage of a mutant gene over a normal gene in a species population would eventually allow the mutation to dominate the species gene pool. What is not generally publicized is the amount of time required for this dominance to take place.

Analysis of a hypothetical mathematical model of a large population containing 0.01 percent of individuals possessing a particular mutation conferring a one-percent breeding advantage showed that the mutation would increase from 0.01 percent to 0.1 percent frequency in the population only after 900,230 generations.²⁵

Paralleling the fruit fly work is the investigation of the effects of neutron irradiation of roses. Dr. Walter E. Lammerts while Director of Research for the Germain's Horticultural Research Division, carried out extensive studies in this area. He states, "More mutations were obtained by the irradiation of 50 rose 'budding eyes' than one could find in a field of a million rose plants in a whole lifetime of patient searching..."²⁶

Even though some of the mutations were useful from a horticultural standpoint in that they possessed additional petals of a unique color, every single mutation was found to be weaker than the variety originally irradiated. Similar results have been obtained by other researchers in this field. Geneticists agree that mutations are generally harmful:

Mutations and mutation rates have been studied in a wide variety of experimental animals and plants, and in man. there is one general result that clearly emerges: almost all mutations are harmful. The degree of harm ranges from mutant genes that kill their carrier, to those that cause only minor impairment. Even if we did not have a great deal of data on this point, we could still be quite sure on theoretical grounds that mutants would usually be detrimental. For a mutation is a random change in a highly organized, reasonably smoothly functioning living body. A random change in the highly integrated system of chemical processes which constitute life is almost certain to impair it--just as random interchange of connection in a television set is not likely to improve the picture.²⁷

In spite of the shortcomings of mutations as a mechanism for evolutionary change, they remain today the backbone of evolutionary theory, the hypothetical principal source of new genetic information which theory requires for the origination of new biological designs by a naturalistic process of evolution. After over a half century of experimentation with mutations, no one has yet produced a new species by either macromutation or selection of micromutations. Nevertheless, the general public is led to believe that mutations have been demonstrated scientifically to be the basic source of evolutionary change.

The presumed mutation which has been most publicized is the one connected with light and dark colored moths in England.²⁸ In mid-19th century England, before the air pollution caused by the use of coal to power the industrial revolution started to darken the bark of forest trees, the population of the peppered moth(Biston betularia) was mostly the light colored phase. Only a very small proportion of these moths exhibited the dark colored phase. These two color phases are the visible phenotypes corresponding to two forms(alleles) of the invisible gene which controls the color of the moths. This is not unusual, for there are many species of moths and butterflies which have different color phases in the same species. In B. betularia the dark phase is somewhat more vigorous than the light phase, but this is normally not the most important factor in their survival, because they rest on tree trunks in the daytime and birds eat them, selecting first the moths which contrast most with the background. On light trees the birds can see the dark moths better, and on dark trees the birds can see the light moths better.

As the industrial revolution proceeded, the light moths became increasingly conspicuous against the darkening background of dirty bark. The birds could see the light moths better and ate more of them. this gave the dark moths the advantage, so they tended to live longer and reproduce more. Thus the proportion of the dark phase allele increased in the gene pool, and the proportion of the dark phenotype increased in the population. In the mid and latter parts of this century the population of B. betularia has been predominantly the dark phase, but the light phase still persists. In recent decades, however, governments and ordinary citizens have become more "ecology conscious," and industries are more careful in disposing of their wastes. As a result, the trees are becoming cleaner and lighter again. Consequently, the dark moths are becoming increasingly conspicuous, birds eat more of them, and the proportion of light moths has been increasing in England. The balance of the two alleles in the population gene pool is shifting again, this time in the opposite direction. This overall process is called industrial melanism.

There in nothing mysterious about the case of the light and dark moths. If one or the other was originally created, then the variety with the opposite allele originated by mutation. Or, alternatively, the original creation included both alleles. In either case, the changing environment brought about changes in the balance of the two alleles in the gene pool. The phenomenon of industrial melanism is a valid, scientifically demonstrated illustration of natural selection in action. But is it a demonstration of "evolution in action"? British biologist Kettlewell asserted in the published report of his observations of birds eating moths perched on trees in an English forest that, had he lived to see this, he "would have witnessed the fulfillment of his life's work." Does it indeed provide scientific support for the grand Darwinian scenario of evolution from amoeba to man? Absolutely not. This claim, made in many biology textbooks during the past several decades, has just recently been replaced by a correct evaluation, i.e., that it demonstrates natural selection in action.

But now a new error is being promulgated in the textbooks which popularize a new definition of evolution. Evolution is defined as "change over time," and more specifically, as "a shift over time in the composition of a population gene pool." Using these erroneous definitions, overzealous secularists in schools and universities can and do fool many students into believing that evolution from amoeba to man is a fact. What the reproducible data do demonstrate is merely limited genetic change within species limits. The other claim of virtually unlimited change during billions of years from amoeba to man is not a scientific deduction, but a monstrous extrapolation from the data, an extrapolation which is not justified by the facts.

References

24. Boyd, Wm. C., Genetics and the Races of Man (Little, Brown, Boston, 1950), p. 146.

25. Lammerts, Walter E., in Why Not Creation? (Presbyterian and Reformed Publishing Co., Nutley, NJ, 1970), p. 301.

26. Crow, James F., Bulletin of Atomic Scientists, Vol. 14, Jan. 1958, pp. 19-20.

27. Bishop, A.J. and L.M. Cook, Scientific American, Vol. 232, Jan. 1975, pp. 90-99.

28. Davidheiser, Bolton, op. cit. (ref. 19), pp. 14-16.