The possibility of the inheritance of acquired characteristics is as yet a matter of doubt. The term ”inheritance” has been sadly misused in this connection, for many of the qualities popularly called inherited are merely acquired during gestation. For example, the habitual use of morphine by the pregnant woman is followed by the birth of a baby morphine fiend. The habit is not inherited, it was acquired by the child during gestation. The child became addicted to the use of the drug just as the mother did, by being supplied with it daily. The effects of nutritive conditions before birth are not to be attributed to heredity, any more than are nutritive conditions after birth.
The inheritance of acquired mutilations is apparently impossible, though deformities may be inherited, just as normal structure is. Peculiarities or deformities which render the individual less apt to marry, or less productive, are not perpetuated for many generations, unless there is very persistent inbreeding. The “Hapsburg Lip,” for example, has been for sixteen generations persistent among the descendants of the Hapsburg House. It is shown very clearly in the pictures of the present King of Spain. This unattractive feature was not perpetuated deliberately, as a desirable trait, but it was an incidental factor in an inheritance which was perpetuated by the inbreeding consequent upon political marriages. It is a matter of common knowledge that races and species are modified by changing environal conditions, but it is not easy to determine whether the facts as observed are due to the inheritance of acquired traits, or whether they are due to the persistence of those individuals in whom the traits which facilitate adaptation to the new environment are most prominent. Without attempting to settle the vexed question, some factors concerned in it may be mentioned in connection with the discussion of the effects of therapeutic procedures upon racial development. The fact of the unmodifiability of the structural hereditary substance is shown by the following facts:
The Jews have practiced circumcision since Abraham’s time, at least thirty-eight centuries ago. The necessity for the operation is as apparent among the Jews today as it is among the Gentiles.
The practice of binding the feet of the high-born girls of China is of unknown antiquity. By this custom the feet are made a source of the most intense suffering for weeks and months, and then rendered useless for life. The binding is done in early childhood, before maternity is possible, yet after all these centuries of mutilation, the girl babies of China are born with normal feet.
Among savage races, birth marks are almost unknown, though tattooing is very prevalent. Among different races, there are various habits of tattooing, sometimes of one sex alone, sometimes of both sexes, sometimes in childhood, sometimes in youth. The lack of birth marks is universal.
Galton’s Law of Inheritance seems constant. According to this, if the hereditary substance of each individual be called one, the parents of that individual have given one-half, that is, each parent gives one-fourth; the grand-parents give one-fourth, that is, each grandparent gives one-sixteenth; the great-grandparents give one-eighth, that is, each grandparent gives one-sixtyfourth part of the hereditary substance. The generation preceding the great-grandparents give, all together, one-sixteenth part of the hereditary substance, and so on. One-half plus one-fourth plus one-eighth plus one-sixteenth plus -- through all the past generations, equals one, or the amount of hereditary substance of the individual. This law seems constant, so far as structures are concerned. This includes the inheritance of mutations, variations, and deformities, but not acquired structural changes. It takes no account of acquired traits. Since function exerts so great an influence upon structure, it would appear that the possibility of the inheritance of acquired function would necessitate the inheritance of acquired structural changes. That this is not invariably true is shown by the persistence of non-functional organs,--the pineal gland, for example, the ciliated epithelium of the acqueduct of Sylvius, etc.
Many of the different organs of the body are known to form certain ferment-like substances during their activity which facilitate the metabolism of like tissues all over the body. That is, the active muscle forms a ferment which facilitates muscle metabolism. The active gland forms a ferment which facilitates the metabolism of similar glands, and so on. These ferments are poured into the blood stream, and thus are brought in contact with all other tissues of the body. While these ferments are especially adapted to the function of increasing the metabolism of tissues similar to those which produced them, they have also a certain effect upon all tissues which are engaged in metabolism. Cells of organs or tissues which are stimulated to exhaustion do not form these ferments, or if they do form them, use them for their own metabolism. At any rate, the ferments are not thrown into the blood stream by exhausted tissues. The germ cells are formed before birth. They lie dormant, but not dead, through intra-uterine life and childhood. At about the time of puberty, they begin to undergo more rapid metabolism, and the process of maturation begins. During all the reproductive life of an individual, some of the germ cells are undergoing the changes incident to maturation. The metabolism of the germ cells undergoing maturation is very intense. The foregoing statements are the facts of the case, recognized by biologists. The theory is, in brief, as follows:
Since the germ cells are alive, even though dormant, during early life, it would seem that they might be affected, in some degree, by changes in their environment, that is, by changes in the character of the blood and lymph. Since metabolism is more intense during the period of maturation than in early life, the changes in the blood and lymph would exert the more profound effects at that time. The ferments poured into the blood stream by the tissues functionally most active may be supposed to affect the metabolism of the germ cells, as they are known to affect the metabolism of other cells of the same body. The ferment produced by any given tissue in its activity would induce a corresponding change in the metabolism of the germ cells in such a manner as to cause an increased efficiency of these parts of the hereditary substance which control muscular development. Or, the increased activity of nerve cells would produce ferments which would cause increased efficiency of those parts of the hereditary substance which control the development of the nervous system. The individual resulting from the development of a germ cell from a parent whose muscular development was unusually fine would thus have certain possibilities of muscular development, greater than those possessed by the ordinary individual. The individual resulting from a parent whose nerve cells were unusually well developed would have certain possibilities of nerve development greater than those possessed by the ordinary individual. If any parent uses any organ or cell group to absolute exhaustion, the ferments normally produced by the normal activity of that organ or cell group are lacking in the blood stream, and therefore in the effects upon the germ cells. Inasmuch as metabolism is more intense during maturation, the effects of changing habits exerts most pronounced effects upon those germ cells which happen to be undergoing the process of maturation at that time. These items account, in part, for the fact that children born of the same parents display such different characteristics, and that children often seem to lack those qualities in which their parents most excel. (Note A.) Since the germ cells are affected by the nutritional conditions of the body in which they live, it is very probable that they are affected by the presence in the blood stream of abnormal substances which had been administered as a therapeutic procedure. It is not needful to accept the theory of the inheritance of acquired characteristics in order to recognize the effects of therapeutics upon racial development.
Aside from hygienic teachings, such as the laws given by Moses governing matters pertaining to health, there was very little in the way of rational therapeutics until comparatively recent times. There have been rational teachers, “doctors,” through all the ages, but their teachings have not met with wide acceptance unless they were associated with religious ceremonies. The condition of affairs was somewhat peculiar. The hygienic measures not associated with religious ceremonies were disregarded, and those which were associated with religious ceremonies were soon over laid with irrational formalism, and hedged about by restrictions which rendered the whole procedure absurdly inefficient from the hygienic standpoint. So long as they were obeyed, these hygienic teachings affected the development of the race only favorably, since those measures which make for the best development of the individual make also for the best development of the race.
The witchcraft idea has held control of therapeutics from ancient times even until the present. Under the influence of this superstition, the laws governing the development of other organisms were permitted to modify the development of the human race. Perhaps it might be said that intellectual development was hindered by the perpetuation of the witch idea in medicine, but this influence must have been of very little influence upon the whole. The acceptance of a wrong idea precludes any investigation into its truth, certainly, but it is probably true that the race accepted witchcraft because people were ignorant, rather than that they were ignorant because they used the witch idea in medicine. Under such conditions, the progress of the race was not affected either for good or for ill by therapeutic procedures. The strongest in body and the most aggressive in mind lived longest and with most pleasure, and left the greatest number of the most vigorous children. The weakly and feeble died early and left no children, or at most, only a few feeble offspring who soon perished. The early races fought their way to physical perfection through the same paths that are followed by plants and animals. They found no royal road to racial progress,--there is no royal road to racial progress.
The first use of drugs was based upon the idea that Mother Nature had, hidden away somewhere, a certain specific for all the ills of human existence. She was supposed to have given hints as to their use, as children do in their play, by making the form or the color of the plant indicative of its function. For example, people with bad livers are yellow; there is a plant with a yellow blossom and a flat, liver-shaped leaf; therefore, this plant is good for bad livers, and is called liverwort. Another plant has a heart-shaped leaf; it is therefore good for cardiac disorders. The mandrake has a root shaped like the human body. The childless woman sought carefully the root which most exactly resembled the child she desired, and was made fertile. Bitter and nauseating doses were given in the hope of “driving out” the disease, as if there were a real thing in the body which should be treated. A favorite method of dealing with hysteria rests upon a misconception of the nature of disease. The globus hystericus was supposed to be the womb which had traveled into the throat. So, they put musk, or other substance with a pleasant odor upon the lower part of the body, and assafoetida upon the chest and throat. The evil odor was supposed to drive the womb away from its abnormal position, and the pleasant odors were to attract it to its proper place.
After the days of the simples, and developing from these came the time of the really effective drugs, -- drugs that influenced the functions of the body in strange and diverse manners. These increased, decreased, and modified cell metabolism in a degree that now seems incompatible with life, to say nothing of health. By means of this urgent dosing, one of two effects was secured, -- either the patient died, and the natural forces looking to the extirpation of the unfit were accelerated, or they survived, and thus perpetuated their immunity to the drug employed. Those who were unusually susceptible to drugs died early in life. Those who were able to endure the strongest drugs in the largest doses survived longest, and left descendants who were even more adapted to the use of drugs than themselves. The drugs employed most frequently were of two classes, -- purgatives and stimulants. To this acquired adaptation to purgatives we owe, in part, the tendency toward constipation which is so annoying a factor in the lives of so many people nowadays, and to the acquired adaptation to the use of stimulants we owe, in part, the tendency of the present generation to the use of alcohol, tobacco, etc. The toleration of our own race for stimulants far in excess of the toleration of any animal for them, and far in excess of the toleration of any of the savage races for them, is proof that our past habits of drugging have not been altogether fruitless. The craving for stimulants seems almost universal. If the habit of using alcohol is not present, its place is very often supplied by other abnormal stimulants, or, it sometimes happens that exciting contests, the “speed madness” affords the stimulant required. The present nerve racking speed of life, this turmoil of ceaseless competitive endeavor, this artificial and hysterical stress over unimportant matters, is not the product of the habits of this generation alone, it is the natural inheritance we have from the therapeutic procedures of our ancestors. “The children’s teeth are set on edge.”
The tendency toward toleration in the use of poisons was not so effective as it might have been for several reasons. The use of poisons was always abhorrent to the more normally minded among the people, and these, partly because of the strength which enabled them to resist the popular prejudice in favor of dosing, partly because of the lack of the drugs themselves, were rendered the more fit to persist in inheritance. This factor was the stronger in that the immediate effects of the drugs as given in olden times were very unpleasant. The drugs were often very costly, and the doctors guarded the secrets of their preparation with great care, so drugs and doctors were not freely employed in trivial disorders. More potent, perhaps, than any of these factors is the habit of normal living, fixed in the cells of our bodies for generations not to be counted. The law is absolute, that those things which make for the highest and ultimate good of the race persist; but those things which affect racial characteristics adversely perish, and with them perish the structures displaying these traits.
The effects of surgery upon racial development are probably not very profound. The facts already mentioned seem to prove beyond question the impossibility of the inheritance of acquired mutilations. It is true that by means of surgery the lives of the unfit may be rendered longer and more fertile, and that weakness may thus be perpetuated in a certain degree. It is also true that unwarranted surgical interference often shortens lives which may or may not be worthy of perpetuation. No doubt much gynecological surgery eliminates the possibility of conception unnecessarily. Many of these persons probably would have been barren, anyway, and those who were not barren by virtue of the disease which rendered the operation permissible are often unfit for maternity. Those who die prematurely because of unwise surgery probably include some of those whose descendants would have been of value to the next generation, and some whose descendants would simply carry a little further the weaknesses which rendered the surgery permissible. The survivors of any surgical operation, whether wise or unwise, do not transmit any of the effects of the mutilation to their children. They may, however, be themselves poorly nourished and weak, because of a poor recovery from unwise surgery, and their children may be affected, directly or indirectly, by this malnutrition. Considered in its broadest aspect, rational surgery must be considered a factor of value in the development of the race, while unwise surgery simply assists in the elimination of the unfit.
Anyone who studies the family history of mental defectives and the insane must be profoundly impressed with the very large number of alcoholic, syphilitic and tubercular people among the ancestors of those unfortunates. Whether this is indicative of the inheritance of acquired characteristics, or whether the facts are to be explained by the supposition that the same instability is at the basis of all these conditions, is a question whose discussion is beyond the limits of such a volume as this. There yet awaits much experimentation and observation before the problem can be solved in any satisfactory manner. That a certain instability of the neurons is in the last analysis the cause of every mental, and of nearly, if not quite, every moral obliquity seems to be fairly well supported. The family of the confirmed drunkard is placed at four generations, unless it is saved by frequent inter-marriages with families of unusual physique and right living. Even then, persistent alcoholism will extirpate any family in a very few generations, and its members will pass through various stages of hysteria, epilepsy, insanity and imbecility to extinction. Given a certain instability of the neurons, and we may find, in one child, imbecility, in another, periodical alcoholic excesses, while another may seem even unusually bright until some urgent physical or mental stress initiates a complete break-down, and he becomes insane. Such as these, if they leave children, bequeath to them, not necessarily the disease from which they themselves suffer, but any of the other forms of manifestation of nervous instability. Any long continued disease, or especially unhygienic surroundings, or any severe mental or emotional stress lessens the powers of endurance, the forces of resistance, of the whole body. Since the neurons are normally the most highly specialized, and therefore the most unstable of all the cells of the body, they display in a most conspicuous manner the effects of constitutional weaknesses. Note A.—If this theory be true, the maintenance of a normal life during the youth of the parents is essential to the health of the offspring. Temporary goodness is not enough to provide for a good inheritance. The effects of a life of bad habits are not to be altogether or immediately evaded by sudden reformation. On the other hand, the effects of a good life are not lightly set aside, and the reformation does have its effect for good. If this theory be true, the time for the beginning of the development of a human being should be well chosen. The time for the maturation of the germ cells is fairly well known, and for a somewhat longer period than that required for that process the health and nutrition of the parents should be above reproach. Pregnancy should never be permitted to begin during a time of fatigue, or of ill health from any cause whatever, or of any abnormal mental, or moral, or physical condition of either parent, nor for some weeks after a period of any form of malnutrition. If this theory be true, it becomes possible for an individual to reclaim his own faulty inheritance for the sake of his children. It becomes possible for all who have children to hope to elevate the race in a perceptible degree, so that the next generation may have a better inheritance than our own. On the other hand, it is an indelible tracing that is being written upon the structure of the cells which are to exist for all time to come. Somatic cells die, and their history dies with them, but the germ cells are as immortal as time, and their history affects the endless future. For even if the cells are so abnormal as themselves to die, the future of the race is affected by the absence of those who should have lived. The responsibility for the future of the race is not eliminated by the fact of childlessness. If this theory be true, the attitude of the physician toward matters pertaining to reproduction, nutrition, and morality is a very important one. Such questions as these should be settled by people who have made a careful study of the matter. Doctors and teachers are the people from whom such instruction must come. These must instruct parents, chiefly, and through them, the children.
Theories of Heredity, in E. B. Wilson’s “The Cell in Its Development and Inheritance.” The Maturation of the Ovum, Ibid. Spermatogenesis, Ibid |