Important Laws of Heredity

Parent and Child, Volume III
by Mosiah Hall

(Page 3 of 10)

A Wise Application of the Laws of Inheritance Is the Most Certain Means of Developing a Superior Race

In the preface of Dr. Guyer's remarkable book, "Being Well Born," we read the following: "It is no exaggeration to say that during the last fifteen years, we have made more progress in measuring the extent of inheritance and in determining its elemental factors than in all previous time." If this is true, it would seem to be almost criminal for teachers and parents to neglect to acquaint themselves with the fundamental laws of heredity. This author says further: "Since what a child becomes is determined so largely by its inborn capacities, it is of the utmost importance that teachers and parents realize something of the nature of such aptitudes before they begin to awaken them. For education consists in large measure in supplying the stimuli necessary to set going these potentialities and of affording opportunity for their expression."

Mendel's law is probably the most important known principle of inheritance. Through its application practically all of the improvements in plants and animals have been brought about. This law may be explained as follows: A certain kind of pure bred fowl is found which is either pure white or black. If either color is mated with its own color the resulting progeny will be true to the color of the parents, but if a white and a black are crossed the result will be blue fowls possessing one-half the characteristics of each parent, but strange to say, if two blue fowls are mated the progeny will not be all blue, one-fourth will be white like one grandparent, another one-fourth black like the other grandparent, and one-half will be blue like the parents. If this experiment is repeated with plants and animals having opposite characteristics, the same ratios as above always result. This indicates that truly heritable traits or characters are separate units and are inherited independently. The breeder is thus enabled through selecting the traits or characters that are wanted and crossing them with a well-known stock, to produce almost any trait or quality that he desires. This law makes it possible to estimate the results of cross breeding with almost mathematical exactness. Improved varieties of fruits, grains and vegetables have been produced in this manner, and with animals marvelous results have been achieved.

Luther Burbank, in his little book, "The Training of the Human Plant," says: "There is not a single desirable attribute which, lacking in a plant, may not be bred into it. Choose what improvement you wish in a flower, a fruit, or a tree, and by crossing, selection, cultivation and persistence, you can fix this desirable trait irrevocably." And further: "If then we could have twelve families under ideal conditions where these principles could be carried out unswervingly, we could accomplish more for the race in ten generations than can now be accomplished in a hundred thousand years. Ten generations of human life should be ample to fix any desired attribute. This is absolutely clear, there is neither theory nor speculation."

Acquirements of parents during their lifetime, according to the best authorities, are not transmitted to any noticeable extent to their children. This appears to be due to the fact that the cells concerned in reproduction are set aside during embryonic life and from then on are practically unmodified by the succeeding development and experiences of the parent. In fact, during the lifetime of the individual, the germ cells are so completely isolated from the growing organism that nothing but nourishment in the shape of blood can possibly reach them, hence they can be affected only by a vitiated or poisonous blood supply. It seems to be true, therefore, that only the old, deeply-impressed traits, capacities, or racial characters can be inherited. This is, no doubt, the chief secret of the power of heredity to breed true.

It has been a popular belief that if parents acquired skill in music, mathematics, or special ability in any other particular that such ability could be imparted to their children, but in the light of the above facts, this appears to be impossible. Of course, if such ability is a slumbering, inborn trait of either parent, or of some immediate ancestor, the ability might be transmitted.

It is reasonable to suppose, however, that any acquired trait or ability of the parent, if practised and continued steadily by his children and their descendants for many generations, will come to be an inborn trait or character capable of being transmitted. Otherwise, it is extremely difficult to understand how the human family can progress and become permanently improved.

Galton's law is believed to be approximately correct. It may be stated as follows: Children inherit on the average one-half their characteristics from parents, one-fourth from grandparents, one-eighth from great-grandparents, and so on in ever diminishing ratio to remote ancestors. But owing to the fact that some inheritable traits or characters are likely to be dominant and others recessive, Galton's law must be modified, so that only under the most favorable conditions can it be regarded as reliable.

Owing to the fact that the primary elements or traits of character contributed by each parent may combine in many ways in the embryo, considerable variation in the children of the same parents is inevitable - one child may resemble the father, another the mother, and yet another some near ancestor. Variability is, therefore, the rule among offspring in the same family, and in some instances it is decidedly pronounced, but in all cases, the variation must be confined to the possible combinations of characters transmitted from parents and ancestors.

The law of regression represents the tendency of the extreme elements of the race constantly to seek the middle or mediocre level. For example, the children of superior parents are not likely to be so brilliant as their parents, and the offspring of inferior people are somewhat better than their parents. This "drag of the race" or "pull of ancestors" is no doubt due to the fact that selection has never been practiced, hence the two-thousand nearby ancestors were most likely an average lot of people, and the "pull" is from the higher towards the lower level. The "pull" is a help to the children of inferior parents but is a handicap to the superior.

If long-continued selection of parents were practiced, the regression would disappear and the "pull" would be upward. Selection of parents possessing superior elements of character and the prevention of the unfit and the criminal from propagating their kind, seem the surest hope we have of producing a permanently higher type.

It is well known that the extremes of the race are less fertile than the means; and since fertility is the chief factor in fixing the type, in the absence of selection and repression, the race appears doomed to remain at the dead level of mediocrity. The tremendous significance of this fact is that the welfare of the race - the gradual substitution of a superior for the present mediocre type - rests absolutely upon the willingness and ability of the superior class to do their full share in propagating the race.

Lesson II

Questions for Discussion

1. What is the principle of heredity as discovered by Mendel? Explain by illustrating how it works out in plants and animals.

2. What practical application is made of this law in producing better seed and better breeds?

3. Illustrate Galton's law.

4. What significance has these laws in the improvement of the human race?

5. Account for the variability of children in the same family.

6. Why are some children inferior, some superior to their parents?

7. Illustrate the "pull of ancestors."

8. How might this "pull" be made upward instead of downwards, as it now seems to be?

9. What sacred responsibility rests upon superior people to propagate the race?

10. What are the gospel teachings regarding mixed marriages and the rearing of families?

11. What practical steps can and should be taken to prevent feeble-minded and vicious people from propagating their kind?

Reference: The Jukes-Edwards family by Dr. A.E. Winship. If this book be available, have some member of the class make a report on it. "Training the Human Plant," and "Being Well Born," will also be found helpful here.

Child Study and Training
1916