"VITAL ARTICLES ON SCIENCE/CREATION"

Apri 1987

No. 166 MUTATION FIXATION:

A DEAD END FOR MACRO-EVOLUTION

E. Calvin Beisner, M.A.

Most arguments against the possibility of mutation as a mechanism for

evolution revolve around two premises: that mutations are almost always

harmful, and that the idea of their improving rather than harming or-

ganisms is contrary to the Second Law of Thermodynamics, which tells

us that matter and energy naturally tend toward greater randomness

rather than greater order and complexity. These are two sides of the

same coin, actually, the latter arguing from principle and the former from

empirical observation.

Rarely, though, do arguments against mutation as the mechanism for

evolution consider at once the many conditions that must be met if

mutation is to bring about macro-evolutionary change (that is, change

from one basic kind of life to another). Yet examining the probabilities of

these conditions all being met together provides excellent evidence

against evolution and in favor of creation.

Fortunately, geneticist R.H. Byles has made the job easy for us by

discussing nine important conditions in an article on the subject.'

1. Neutral Enuironment

Byless first condition is: "Natural selection must be inconsequential

at the locus or loci under investigation." This is because natural selec-

tion tends to work against fixation of mutations-in other words, it tends

to prevent their becoming a permanent part of the gene pool of a popu-

lation. Natural selection keeps things stable rather than helping them to

change. B. Clarke points out that even so-called advantageous mutations

are harmful in that, because of increased competition, they can reduce

population size, making their fixation nearly impossible. He adds that

they will almost certainly lead to extinction of the mutant gene or

organism, and possibly even the entire population.2

The effect of Byles's first condition is that the environment must be

selectively neutral, or else the mutant gene will never be retained in the

population, preventing even slight change. But according to J.T. Giesel,

most locations are almost certainly not selectively neutral.3 Thus, in the

vast majority of cases, Byles's first condition will not be met.

No Structural Change

Byles's second condition is: "There must be no pleiotropic effect

involved math the locus or loci or, if such effect exists, all the phenotypic

structures involved must be selectively neutral." This means that there

either must be no changes in physical structure involved, or they must

be selectively neutral. If none are involved, then of course evolution does

not occur. But if only those occur that are selectively neutral, then they

are of no advantage to the mutant and survival of the fittest does not

affect it or its non-mutant relatives; again, no evolution.

Not only would mutations that met this condition appear to contribute

little or nothing to evolution, but also they would appear never to happen

-or nearly never, anyway. G. Ledyard Stebbins tells us that within the

gene there is no such thing as an inactive site at which a mutation will

not affect the adaptive properties of the gene.' "Every character of an

organism is affected by all genes," writes Ernst Mayr, "and every gene

affects all characters. It is this interaction that accounts for the closely

knit functional integration of the genotype as a whole."5

In other words, there may well be no such thing as a mutation having

no structural change in the organism. Yet Byles says that a requirement

for the fixation of a mutation is that it have none, or that the effect it has

must be selectively neutral. Neither case appears ever to happen, and

even if the latter did, it would not lead to macro-evolution since it would

leave the mutant no more "fit" than any of its relatives. Indeed it would

probably be less "fit" because of the tendency of natural selection to

weed out rather than preserve mutations in a gene pool.

Net Effect Must be Unidirectional

Byles's third condition is: ". . the mutational event must be recurrent

and, forthermore, the rate of back mutation must be so small as to be

irrelevant." Byles himself admits, though, that even recurrent mutations

are almost never retained in the population: ". . non-recurrent mutations

have a very low probability of remaining in the gene pool at all ... the

odds against a recurrent mutation being retained in the gene pool for any

significant number of generations are very high." And even "most re-

current mutations have been observed to retain the potential for back

mutation." It seems that neither part of his third condition MAII be fulfilled;

yet Byles makes it clear in his article that all the conditions must be

fulfilled in order for mutations to be fixed in a population.

High Mutation Rate

Byles's fourth condition is: "The mutation rate at the relevant locus or

loci must be very large." Yet Francisco Ayala says, "It is probably fair to

estimate the frequency of a majority of mutations in higher organisms

between one in ten thousand and one in a million per gene per generation."6

Byles himself comments on Lerner's estimate of one hundred mutations

per one million gametes (one in ten thousand). "Obviously, a mutation

rate this small, even given a complete absence of back mutation (which

appears never to occur), would result in a very small change in a given

gene pool, even given large numbers of generations. This has long been

considered one of the major stumbling blocks to the [Probable Mutation

Effect]. . . In order for the P.M.E. to be effective, very high mutation

rates are clearly necessary."

So it appears that this condition, too, is likely never met in nature.

Large Population

Byless fifth condition is that the population involved must be large.

He stipulates this because small populations can easily be destroyed by

a mutation. And, as population size decreases, the probability that a

mutation will be eliminated increases.

Dobzhansky, Hecht, and Steers, however, postulate that a small

population vath much inbreeding is important: ". . the ideal conditions

for rapid evolution ... are provided by a species which is divided into a

number of small local sub-populations that are nearly but not completely

isolated and small enough so that a moderate degree of inbreeding takes

place. . . The division of a species into two or more subspecies is of

course dependent on complete isolation being achieved in some way."7

It seems that evolutionists themselves have realized a great problem

but are unable to deal with it. In a small population, a mutation will

almost certainly be eliminated. Yet a small population is needed for evo-

lution to occur. Here indeed is an impasse. But the problem gets worse.

Byles adds (in contradiction of Dobzhansky, Hecht, and Steere), "If

the investigator is dealing with a population which is undergoing contact

with genetically dissimilar neighbors, the effect of the mutation is inevi-

tably so minor as to be indetectable. Therefore, to argue that mutation

is the cause of change in the population's genetic structure, one must

also of necessity argue that this population is not undergoing a process

of hybridization." In other words, if the population is large, the effect of

the mutation is almost nil. Even when Byles's condition is met, then, the

effects of the mutations are almost zero on the entire population. And,

furthermore, while Dobzhansky, Hecht, and Steere say some interbreed-

ing between dissimilar populations is necessary, Byles says it is death

to evolutionary change.

Selective Neutrality of Polygenes

Byles's sixth condition is: "Polygenes are not relevant to this argu-

ment, unless the entire anatomical complex is itself selectively neutral."

This means that for organisms of many genes, the mutation cannot be

fixed unless the whole anatomical structure of the organism is selectively

neutral relative to the gene which mutates. That this does not occur was

shown in our discussion of the second condition.

Little Hybridization

Byles's seventh condition is: "There must be little or no hybridizing

admixture." This of course is to avoid making the mutation itself insig-

nificant. But if the effect is actually significant, then this contradicts his

second condition, which was that the mutation must cause no significant

structural change (see under point 2 above). Furthermore, the only way

in which to have no hybridizing admixture is to have a small population

that is isolated from others of the same kind. This contradicts his fifth

condition. If the population is small, the probability of a mutant gene's

being eliminated rises steeply.

This seventh condition, if fulfilled, makes evolution impossible because

the mutation would not be retained due to the necessarily small popu-

lation. But if unfulfilled, it leaves evolution impossible due to the insig-

nificance of the effect of the mutation.

Necessity of High Penetrance

Byless eighth condition is: "The genetic structures involved must

have high 'penetrance.' " Put simply, this means that the genes must be

highly susceptible to mutation. It thus means almost the same as

Condition Four.

Yet it occasions another problem. As soon as the structure becomes

highly susceptible to mutation, it must also become highly susceptible to

back mutation. But his third condition states that the rate of back muta-

tion must be irrelevant, Again there is contradiction: fulfill Condition

Eight and you can't fulfill Condition Three. Fulfill Condition Three and you

can't fulfill Condition Eight. Yet Byles says that all of the conditions must

be fulfilled for mutation fixaton to occur; and without mutation fixation

there is no macro-evolution.

High Heritability

Byles's ninth condition is: "The phenotype must have high heritability."

This condition is almost never met for mutational phenotypes. Byles

himself told us that the probability of retaining even a recurring mutation

is "very low."

It appears that the probability of meeting any one of these conditions

in nature is extremely low, if not non-existent. Recall now that the fifth

and seventh conditions effectively cancel each other out, as do the third

and eighth, and we are forced to the conclusion that it is impossible to

meet all the conditions. Mutation cannot be the mechanism for macro-

evolution.

1. R.H. Byles, "Limiting Conditions for the Operation of the Probable Mutation Effece'Social

Biolo_qy, 19 (March, 1972):29-34. All citations from Byles in this article are from this source.

2. B. Clarke, "Mutation and Population Size," Heredity, 31 (Dec., 1973):367-79.

3. J.T. Giesel, "Maintenance of Genetic Variability in Natural Populations; Alternative Implica-

tions of the Charlesworth-Giesel Hypothesis," American naturalist, 106 (May, 1972):

412-14, p. 412.

4. G. Ledyard Stebbins, "Building Bridges Between Evolutionary Disciplines" Taxon 23(1)

(Feb., 1974):11-20, p. 14.

5. Ernst Mayr, Populations, Species and Evolution (Cambridge, Mass.: Harvard University

Press, 1970), p. 103.

6. Francisco J. Ayala, "Teleological Explanations in Evolutionary Biology," Philosophy of

Science, 37 (March, 1970), p. 3. Cited in Henry M. Morris, ed., Scientific Creationism

(San Diego, Calif.: Creation-Life, 1974), p. 55.

7. Theodosius Dobzhansky, et OI., Euolutionar_v Biolo_qy, Vol. 2 (N.Y.: Appleton-Century-

Croft, 1968), p. 259.