INHERITED POTENTIAL

When a man and a woman are mated, each passes onto their children one half of the inherited potential they themselves have received from their parents. Present indications are that the characteristics which each will contribute to the child are carried by genes. For each character that a man or a woman may contribute to his offspring, there are usually two alternatives -- or to put it another way, the potential is in duplicate and at the present moment chance appears to govern which of the two alternative contributions the individual will pass on. For example, a brown-eyed parent may pass on to his children that which will give them blue eyes instead of brown eyes like his own.

There are a very large number of alternatives, as for example the control of hair colour (fair or dark). Modern research into the nature of these controlling genes (and there are thousands of them in each individual) has shown that for one reason or another, these genes get damaged and appear in a condition which is called mutant. Normally a gene once mutated remains mutated, i.e., damaged, as it is passed through each successive generation. The inevitable conclusion of this finding is that the amount of material controlling inheritance becomes increasingly damaged in its nature with each successive generation. In other words, each generation may be expected to be less viable in some way than the preceding one, even though the damage may be so small as to be, to all intents and purposes, of little consequence.

Now, if a parent with a particular damaged gene complex passes onto a son and a daughter this damaged material, these offspring will both share damage at the same point (or locus) in their own gene complexes. Should these two marry, in their mating the particular segments of damaged material are bound to be brought together in a way that enormously reinforces their power to effect the growing embryo detrimentally. On the other hand, if such a son marries a girl from some other family who, although suffering genetic damage like the rest of us, has not inherited damage at the same place in the gene chain, the effect of bringing the two "damages" together is likely to be much less serious, for the areas of damage do not coincide. For this reason, marriages are safer from the physiological point of view when the two parties do not share the same kind of damage in their genetic make-up at the same locus.

At the beginning of this grossly over-simplified statement, I said that the amount of damaged material increases with each generation. It follows logically, therefore, that each previous generation has suffered less genetic damage. We can extrapolate backward in time until we begin to reach a point at which damage to the genetic material would be vastly less than it now is: logically, if we go back far enough, it would not exist at all. It is true that this may not be a straight line function, that the improvement in reverse may follow a curve which slows up in its approach to perfection and never quite reaches it. This is possible. There is no need to make this assumption, however. There is no reason at all why the first human beings may not have had a perfect constitution, in which case brother-sister marriages at the time would be absolutely harmless.

Before we return once more to this aspect of the paper, let us look briefly at some of the present evidence for the detrimental effect of close-relationship marriages. The underlying causes for the deleterious effects of incestuous matings are pretty well understood and have been variously expressed. For those who have some knowledge of and interest in the more basic principles of human genetics, the following miscellany of quotations will perhaps be of value and, taken as a whole, state the case clearly enough. For example, Bentley Glass, in a paper which gives some consideration to the possibility of "improving" the human stock by inbreeding in the way this is done with plants, made the following observation: ⁽⁸⁾

Within the past three centuries human populations have increased enormously in size, and an approach to panmixia has become characteristic of the major races of the world population. The result of this has been to render man a highly heterozygous animal. Beneath the facade of dominant traits expressed in the phenotype of each individual, there lies concealed a great number of unmanifested recessive genes, kept in a heterozygous condition within the population. From studies of mutation in man, mouse, and Drosophila it is apparent that the manifestation of the majority of these recessives would be deleterious in most, if not all, environments. In fact, one quarter to one third of them are lethal when homozygous.

New lethal and deleterious mutations arise in each generation at an average frequency that is estimated to be of the order of 1 in 100,000 per locus per gamete, or higher. The number of different genes (i.e., loci) in man may be taken as 10,000 or perhaps even 40,000. It follows that at least one gamete in ten will bear a new mutant, nearly always of a lethal or detrimental sort. The effect of these is not normally evident, since they are kept heterozygous. Any return of the human population to closer inbreeding may be expected to bring these recessive traits to the surface. . . .

Human pure lines selected for (say) intelligence would most probably be weak in vigour, low in fertility, and beset by numerous hereditary defects.

From a mathematical point of view, the situation may be put in this way: matings among first cousins (as in Darwin's case, for example, or his sister Caroline's case) result in the offspring having identical genes in a ratio of 1 to 7. ⁽⁹⁾ Many of these genes will be recessive mutants and therefore detrimental to the possessor when inherited homozygously. Mating of uncle to niece, or nephew to aunt, raises this ratio to 1 to 3. Matings among brothers and sisters raises this ratio, often disastrously, to 1 to 1.

Willard F. Hollander, in an article significantly title, "Lethal Heredity", commented on this situation as follows: ⁽¹⁰⁾

Sometimes a mutation is so radical that nothing can be done to prolong the animal's life to maturity. This is what is known as a lethal mutation. Often it kills the animal while it is still an embryo. Most lethal mutations are recessive, however, and are carried unsuspected by normal appearing animals. . . .

The quickest way to expose lethal traits is by intense and continued inbreeding. In man such matings are generally illegal or tabu; the experience of the race indicates bad results . . . the outcome is generally detrimental. When inbreeding begins, the heredity seems to be breaking down. All sorts of defects and weaknesses appear. The average life span decreases. After a few generations the family often becomes extinct.

We shall have occasion to return to this latter aspect of the problem, but we may just note here Hollander's conclusion: ⁽¹¹⁾ "The abundance of hidden lethals and hereditary defects exposed by inbreeding must be seen to be believed. It seems safe to say that very few individuals of an ordinary mixed population fail to harbor one or more. Whence came this multitude of skulking malefactors?" To this last point we must likewise return subsequently, for the perceptive reader may already have noticed that animals are afflicted with these imperfections as well as man and they cannot therefore be attributed in a direct way (at least insofar as animals are concerned) to a fallen nature. The fall of man may be the originating cause, but this cause cannot be applied directly to animals unless animals are included among sinners -- though Scripture has intimations even for this. . . . ⁽¹²⁾

Under normal circumstances inbreeding, therefore, leads to a decline in overall vigour for a number of generations. In many cases the detriment is so severe that the line becomes extinct. However with very careful management such inbred lines, if they can be preserved through ten or twelve generations, tend to settle down in a modified form, i.e., with a somewhat different character. This different character may turn out to be a desirable one from the breeder's point of view, having lost certain of its former strengths and accumulating many new weaknesses, but having also acquired some new quality which the breeder had particularly in mind. This is true of corn, for example. ⁽¹³⁾ If the inbreeding can be arranged from widely separated lines, the hybrids generally turn out to be more vigorous. This sounds like a contradiction. What is actually meant is that -- by inbreeding one line in one geographic locality until it is highly degenerate and perhaps barely surviving, and at the same time inbreeding another line in another geographic location until it too is degenerate -- if the two inbred degenerate lines are now crossed, the resulting breed may be more vigorous than it would have been if the originals had merely been crossed without first producing the degenerate types. It is not necessary to go into the causes of this somewhat odd but most useful discovery, it is necessary only to include it in this discussion because one commonly hears the statement made that inbreeding produces superior stocks. This is true of plants and of some animals, and it is conceivable that it might be true of human beings. But in the process, the lines degenerate seriously or may die out completely.

On the basis of this theoretical understanding of what is happening, it might be supposed -- and the supposition is borne out by experience -- that in a small population which is multiplying there may appear at first an extraordinary diversity of types. Not all mutations expressed homozygously are lethal, but they are all likely to be more or less effective in substantially modifying the bearer's physical type. As Lebzelter pointed out, a small group of people will share a basically homogeneous culture but show great physical diversity, whereas a larger community of people (because mutant genes are less likely to appear homozygously) will show greater uniformity of physical type but allow a larger measure of cultural variability. ⁽¹⁴⁾ This may very well account for the fact that early man seems to have proliferated types (forerunners of races) in a remarkably short time while at the same time witnessing an amazing measure of cultural conformity. This heterogeneity of physical type appears even within single families, as for example, in the Upper Cave at Choukoutien. ⁽¹⁵⁾ Early human history may have quickly witnessed the emergence of all the racial types which we now think we can recognize in the modern world. There is no need to postulate tremendous eons of time. I prefer the word emergence: most people would prefer the word evolution, and on the basis of the above reasoning they would say, as Franklin Shull said, ⁽¹⁶⁾ that "if a population is very large . . . evolution must be slow under these circumstances," and on the other hand if the population is too small and inbreeding too frequent, the population is likely to die out, being overwhelmed by its own defects. Several royal families have suffered virtual extinction by this very process, and all because they sought to preserve family lines intact.

In some parts of the world there are isolated communities in out-of-the-way villages, even in otherwise densely populated areas in which inbreeding has proceeded for many years. In such communities there is a high incidence of deaf-mutism. W. L. Ballinger reported in one case that forty-seven marriages between blood relatives produced seventy-two deaf-mutes. ⁽¹⁷⁾ In the same connection E. B. Dench remarked, "Consanguinity of the parents is among the most common causes (of diseases in the ear), and the great frequency of deaf-mutism among the inhabitants of mountain districts is probably to be explained by the fact that intermarriages are much more common among such people." ⁽¹⁸⁾ Similarly in Lajous' Analytical Cyclopedia of Practical Medicine, it is noted that "several statisticians have proved that the closer the degree of relationship between parents, the larger was the number of deaf-mutes born." ⁽¹⁹⁾

In The Lancet, a discussion was reported on the risk taken by parents who decide to adopt a child born of an incestual relationship It was observed that, ⁽²⁰⁾

. . . medical practitioners are sometimes asked about the advisability of the adoption of a child born as the result of incest. Such children will have an increased risk of being affected by recessive conditions. In order to get an estimate of the extent of this risk, in 1958 I invited Children's Officers to let me know prospectively of pregnancies or of new births in which it was known that the pregnancy or birth was the result of incest between first degree relatives.

These children were followed prospectively and anonymously through the Children's Officers. The children were known to me by number and correspondence referred only to the child's number. Thirteen cases of incest (6 father-daughter and 7 brother-sister) were reported to me in 1958 and the latest information on them was in midyear 1965 when the children were all 4 to 6 years old. I summarize here the information on these 13 children.

Three children are dead: one at 15 months of cystic fibrosis of the pancreas, confirmed at necropsy; one at 21 months of progressive cerebral degeneration with blindness; and one at 7 years, 11 months of Fallot's Tetratology (this child had an IQ of 70). One child is severely sub-normal, with much-delayed milestones, and was considered non-testable at age 4 years, 9 months, when she had a vocabulary of only a few words. Four children are educatively subnormal; the known IQ of 3 are 59, 65, and 76. The remaining 5 children are normal.

The risk of parents sharing a recessive gene will be four times greater in cases of incest between first degree relatives than it would be between first cousins.

So much, then, for the evidence. Incest today is clearly detrimental in a very large percentage of cases, the risk of defective offspring being so high that every civilized country legislates against the marriage of brothers and sisters. Yet it is a risk rather than a certainty, an important fact which shows that under certain circumstances it might be quite safe -- though the circumstances under which such a union could be predicted safe are not known at present. Current genetic theory does, however, indicate that the number of recessive and damaged genes increases rather than decreases with each generation. It might be thought that if there is a steady increase, the complement of genes in each individual would be by now all damaged in one way or another. Indeed, if the factors which lead to such damage (certain types of natural and artificial radiation and some poisons, and so forth) have always been with us -- a fact which seems likely enough for a very large part of human history -- and if current theory about the vast antiquity of man are really sound (which I don't believe they are), one would have to suppose that the damaging process must by now have almost completed its task. But evidently, even in comparatively recent times, this is not the case, for as we have already noted, both Hawaiian and Incan chiefs successfully married their sisters, and somewhat before that the Ptolemies did so.

It seems to me, therefore, that the evidence does not on the face of it bear out the concept of man as already having thousands of successive generations behind him. The biblical record actually shows only 77 generations from Adam to Christ, ⁽²¹⁾ and if we add to this the two thousand years since, we have something like 100 to 120 generations covering the whole of human history. Since the accumulation of defective genes is meaningful only in terms of their effect on succeeding generations, it is not altogether unlikely that the first human beings (namely, Adam and Eve) were indeed perfect, and that the damage started to be done following the Fall and has accumulated ever since at what seems to be a reasonable rate during these 120 generations, until we reach the present situation in which there are still some possibilities of successful brother-sister matings, though the odds are against it. At the rate at which these mutations occur in each generation, according to current genetic theory, one would not expect to find any undamaged segments of the individuals inherited stock of genes if the human race had been multiplying for thousands upon thousands of generations. We would all be so badly damaged by now that no brother-sister marriage could possibly succeed any longer.

On the other hand, taking the biblical story as it stands, Adam's sons and daughters (Genesis 5:4), of whom Cain was one and his wife another, need not have been carriers of any more than a mere token of damaged genetic stock. Such a marriage need not have endangered the offspring.

There is, surprisingly enough, direct evidence in Scripture that this interpretation of the events is strictly true. We are first of all presented with a list of immediate descendants for some ten generations from Adam to Noah who enjoyed what must be described as magnificent viability. Consider for a moment what was happening during this period of time. Prior to the Flood, man may well have been shielded against at least one source of danger to the genes, namely, cosmic radiation, by the existence of some kind of barrier in the upper atmosphere. There are many who believe that this barrier disappeared at the time of the Flood and could indeed have been related to that event. The pre-Flood population (both men and animals, be it noted) may therefore have suffered little damage to their genes throughout each succeeding generation while these environmental conditions existed.

Added to this is the fact that the population was multiplying during this time so that, even if some damage was occurring, it would become less and less necessary for any man to marry a near relative, thereby avoiding any reinforcement of such gene damage. For this reason, there is little or no evidence that man, physiologically considered, was becoming an inferior creature -- at least, insofar as his inherited vigour was concerned: and the same may well have applied to the animal world.

But then came the Flood, which reduced the world's population to eight souls, all of whom had now accumulated some damaged genes and were also first-degree relatives, i.e., Noah and his three sons. The sons and daughters of the next generation would therefore be also marrying near relatives, and one could only expect as a consequence that evidence of decreased viability would begin to show up, while the potential hazard from cosmic radiation would greatly increase. This could be the answer to Hollander's final query: inbreeding of a greatly reduced population, and exposure to cosmic radiation at a new level -- both as a consequence of the Flood. This is, of course, precisely what did happen and precisely at a rate commensurate with the discovery of modern genetics resulting from experimental inbreeding. Within ten generations (compare Glass's figures) the life span of post-Flood individuals, insofar as they are represented by those whose ages are given in the Bible, had rapidly declined until it was only about one eighth of the pre-Flood period, thereafter slowly leveling off first to 120 and later to three score and ten. ⁽²²⁾

All this makes perfectly good sense and accords very satisfyingly with modern findings, provided that one accepts the whole biblical record just as it stands.

It has been proposed by some who have due regard to the Word of God that Cain married the offspring of some other human creatures who were not descendants of Adam. ⁽²³⁾ They argue this on the ground that Cain would not have expressed any fear of being killed by people who might find him unless there really were people outside his immediate family in Adam. But this assumption need not be made at all, because Cain would not necessarily have knowledge of whether there were or were not other people in the world; even if he had never seen any, he might very well suppose that there were, the supposition being all that was needed to make him afraid. He was simply a man living in fear of suffering at someone else's hand what he had caused his brother to suffer. He had no way of knowing whether there were or were not other people in the world: his conscience served to people it even if no other people had existed.

At the same time, very serious theological problems would arise if Cain had married outside the family of Adam, since his children and his descendants would no longer be strictly "in Adam." This difficulty has been met by some writers by proposing that the Flood destroyed all except those who belonged to Adam's family. It is possible, of course, that this is so, but this vast population must still presumably come to the judgment with all those whom the Flood destroyed, and how then will they be judged? It does not appear to me that the Bible allows for such a contingency. As I see it, the redemption that is in Christ was as applicable to Adam and Cain and all the rest of the patriarchs as it is to ourselves. Would we not then be faced with a kind of half-applicability to Cain's children, and a quarter-applicability to his grandchildren, and so on as the line was diluted -- until there is no applicability at all? The very statement of the situation itself points up the theological problem that such a circumstance would bring about.

To some extent the above interpretation of the identity of Cain's wife has been held as an accommodation to anthropological theory which postulates sub-humans and near-humans at a period in time far antedating the "traditional" date for the creation of Adam. I do not know the answer to the present conflict between secular and biblical anthropology, although I am sure we shall see the answer in due time: but I believe that the Bible itself has gone out of its way to try to make it clear that Adam really was the only man at the time of his creation and Eve the only woman at the time of her formation. Genesis 2:5 tells us that there was not a man to till the ground. Genesis 2:18 tells us that Adam was quite alone and that this was not good for him. Then in Genesis 2:20 we are told that although God brought creatures to Adam who might have been a potential mate for him, there was not found one that was suitable. Finally, as though the point had still not been made quite clear, we are told in Genesis 3:20 that Eve became (so the Hebrew) the mother of all living.

Almost any one of these statements by itself might be thought by some people sufficient to settle the issue. But surely their cumulative effect is about as conclusive as to the intent of Scripture as any such series of statements could possibly be. I believe, therefore, that the only position one can reasonably take in the matter of Cain's wife is that she was one of Adam and Eve's daughters, i.e., a sister of his for we are told that Adam and Eve had daughters as well as sons. ⁽²⁴⁾ From there on, everything makes good sense if one accepts the record as it stands.

One further point only remains to be underscored. This is the perfectly proper absence (if all that we have said thus far is true) of the slightest indication that Cain was contravening any existing prohibition against a brother-sister marriage. His action in destroying his brother is condemned in no uncertain terms, but there is no reference whatever to the existence of any prohibition against incest as appears several thousands of years later in the Book of Leviticus. This not only suggests that the prohibition did not exist, not at that time being required, but that the writer who recorded the events of Cain's life lived at a time when brother-sister marriages were still not viewed as sinful at all.

This absence of any condemnatory note, in a record which elsewhere judges its "heroes" in no uncertain terms when they contravene the laws of God, can only be reasonably accounted for on the grounds that this record as we have it is a contemporary or near-contemporary one and not something concocted by a self-righteous priestly community living some thousands of years after the event. Had they been members of such a hierarchy and had they been knowledgeable enough to realize that the prohibition was not necessary in Cain's time, one might reasonably expect they would have added in parenthesis at the appropriate place in the record some little note to the effect that "at that time there were no laws against incest." As the record stands, one gets the feeling that the writer was totally unaware of any potential hazard in brother-sister marriage.

8. Glass, Bentley, "A Biologic View of Human History," in Scientific American, Dec., 1951, p.367.
9. Darwin's family: see Donald W. Patten, The Biblical Flood and the Ice Epoch, Pacific Meridian Publishing Co., Seattle, I966 , p.244, fn.16.
10. Hollander., Willard F.; "Lethal Heredity," in Scientific American, July, 1952, pp.59-60.
11. Ibid., p.60.
12. The wording of Genesis 3:14 ("above all cattle . . .") may quite justifiably be taken to imply that other animals for some reason were involved in this judgment, a conclusion which would presuppose at least some moral responsibility on their part. It could be argued that in Jonah 3:8 it is assumed that the animals were partly involved in Nineveh's wickedness, the animals also being dressed in sackcloth. The lamb for the sacrifice on the Day of Atonement was to be a lamb of the first year, which again might suggest something analogous to an "age of accountability." The ox that gored a man was to be stoned to death, not merely slaughtered. It is conceivable that this was merely to punish the owner by rendering the slaughtered animal unfit for food, since it would not be properly bled: and the hide itself would probably be marred. On the other hand, it might be argued that the ox itself was being punished. Such passages as these are certainly not unequivocal, but they provide interesting possibilities for further discussion.
13. Inbreeding of corn: Gordon W. Whaley, "The Gifts of Hybridity," in Scientific Monthly, Jan., 1950, p.12.
14. Lebzelter Viktor, Rassengescichte de Menscherit, Salzburg, 1932, p.27. University of Chicago Press, 1948. p.80.
15. Choukoutien diversity : see Franz Weidenreich, Apes, Giants, and Man, University of Chicago Press 1948, p.86.
16. Shull, Franklin, Evolution, McGraw-Hill, New York, 1936, p.146.
17. Ballinger, W. L., Diseases of the Nose, Throat, and Ear, Lea and Febiger, Philadelphia, 8th edition, p.823.
18. Dench, E. B., Diseases of the Ear, Appleton, New York, 1921, p.694.
19. Lajou, Analytical Cyclopedia of Practical Medicine, p.450: the documentation is unfortunately incomplete.
20. "Risks to Offspring of Incest," in The Lancet, London, Feb. 25, 1967, p.436.
21. See "Genealogies of the Bible," Part V in Hidden Things of God's Revelation, vol.7 of The Doorway Papers Series.
22. 0n this see "Longevity in Antiquity and Its Bearing on Chronology," Part I in The Virgin Birth and the Incarnation, vol.5 of The Doorway Papers Series.
23. See the next chapter, "Was Cain's Wife of the Line of Adam?"
24. One further scriptural reference may be mentioned. In Acts 17:26 we are told that God derived all nations that dwell on the face of the earth "from one." In the usual Authorized version rendering the verse reads, "of one blood," but the best manuscripts do not have the word blood. This could therefore be taken to mean in the most literal sense that all nations have had their ultimate origins, not merely in Adam and Eve, but even more specifically -- since Eve was taken out of Adam -- in one man, Adam. This would leave even less room for any multiple-origins theory. I was interested to find this view reflected in the Jesuit commentator Henricus-Rencken's book, Israel's Concept of the Beginning, Herder and Herder, New York, 1964, p.225.

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