HEREDITY.
It may be remarked, in a general way, that the subject of heredity is one
of profoundest significance in its relation to society. Through its
influences the peculiarities and characteristics of families and nations
are largely developed and perpetuated. It "is that biological law by which
all beings endowed with life tend to repeat themselves in their
descendants."[9] It depends upon "an internal principle of vitality" which
is so engraven upon every portion of the system before birth, that its
influence remains through life, and within certain limits pertains alike
to both the physiological and psychological nature. Not that this
influence is such, or operates in such a manner, as to repeat itself in
any stereotyped form, but rather in an endless variety of forms; while no
child resembles its parents in all respects, yet there ever occurs a
blending of the characters of both parents, together with a large number
of those characteristics which have, for long generations, been interwoven
in multiform shades and degrees in ancestors.
Passing now from the general to the particular, we find, first, in
reference to physiological characteristics and peculiarities, that these
tend to repeat themselves more or less directly, so that when they have
once appeared, they may, with reason, again be expected. Peculiarities of
the fingers and toes, of the hair, the shape of the head, the conformation
of the face, and even particular portions of the face, remain for long
periods in the same family and nations. The characteristic form of face
and nose peculiar to the Jew, is an example in point, and so invariable as
to lead to recognition, in spite of the changes and vicissitudes incident
to travel and residence during many hundreds of years, under climatic
conditions of large diversity, and ofttimes experiences of great and
protracted severity.
Not only are such peculiarities as may be considered normal transmitted,
but also such as are abnormal,--a supernumerary finger or toe, or a mole
on some portion of the face or part of the body. A supernumerary finger or
toe may be transmitted for at least four generations, though not to every
member of the family, and the experiments of Mr. Darwin, with birds, go to
show that the tendency to perpetuate such a peculiarity, exhausts itself
after a few generations, the type returning to its original character.
_Fecundity_ is also well known as an inherited character. A mother is
referred to by Girou,[10] as having had twenty-four children, five of
whom, in turn, gave birth to forty-six. A granddaughter of this woman gave
birth to sixteen. The females of some families have all or nearly all
daughters, who, in turn, have more daughters than sons for several
generations. A grandmother had nine daughters, several of whom had no sons
in the third generation.
_Longevity_ has long been recognized as one of the most transmissible of
family traits.
_Caeteris paribus_, persons connected with long-lived families have a much
more tenacious hold on life than others: the capacity for resisting the
changes of climate, the morbific conditions of the atmosphere and soil,
the influences of epidemic diseases, and the experiences of privation and
hardships, is greater than with other persons; and, conversely, the
capacity for resisting these influences is much less with persons whose
ancestors have invariably died at an early age.
So also if a person resembles in physical form, complexion, and
constitution, the ancestors of one side of his family who have lived to
old age, while those on the other side have died comparatively young, his
prospects of longevity are generally strengthened in proportion to the
extent of such resemblance. M. Levy says: "To be born of healthy and
strong parents is to have a good chance of longevity; the energy of the
constitution is the best buckler against the assault of destructive
causes. Rush did not know an octogenarian whose family did not offer many
examples of advanced old age. This observation, made by Sinclair, has
acquired the force of an axiom, so common is it to meet with longevity as
a frequent occurrence among many members of the same family. Inheritance
exercises the same influence on the total duration of life of short
period: in the Turgot family scarcely a member passed the fiftieth year;
he, who rendered it illustrious, died at the age of fifty-three, in spite
of the appearance of great vigor of temperament."
So familiar to every one are the facts connected with the transmission of
morbid physiological processes, that I need not refer to this point
further than to remark, that the phthisical, the cancerous, and the
scrofulous diatheses are those well known to be more surely inherited, and
that through these channels of diseased action whole families cease to
exist after two or three generations, unless the tendency is counteracted
by more vigorous and healthy influences from the other parent.
Passing now to the psychological traits and characters, we observe that
the same law pertains. The heredity of mental qualities is quite as
persistent as that of the physical; imagination, memory, will, intellect,
the sentiments and passions, may all be inherited. It is estimated that
not less than forty per cent. of eminent poets have had illustrious
relatives. The families of Darwin, Cuvier, Bacon, Sir Benjamin Brodie,
John Adams, Lord Macaulay, Madame de Stael, present good illustrations of
the inheritance of intellectual ability.
But no less surely are the characteristics of _morbid_ mental activity
transmitted from one generation to another. The records of asylums all
indicate that the tendency to insanity, in some of its forms, is one of
those most likely to be inherited. It is thought that more than one half
of the admissions to English asylums present evidence of an inherited
taint. The same is probably true in reference to admissions to asylums in
the United States, though it is exceedingly difficult to arrive at the
truth in all cases, inasmuch as many persons are inclined to deny that any
such tendency exists in their families, lest such a fact should appear to
its prejudice in some way or other.
It is not the case, however, that definite forms of insanity always repeat
themselves, but, on the contrary, change, so that a case of mania may
appear in the second generation as a case of melancholia, or acute
dementia; and, _vice versa_, melancholia may appear as dementia.
Information concerning the inheritance of general paralysis is not so
definite; indeed, this form of insanity generally manifests itself in
those having no tendency by inheritance, and would seem to be more
frequent among the strong and robust, and also has a tendency to appear in
the very prime of life.
It is not necessary that the tendency toward unstable mental action should
be fully developed in the parent in order that it may so appear in the
child. Parents who have for years been very odd or singular in their
habits of life and manner of speech and mental operations; those who are
subject to periods of depression, and are accustomed to look upon the dark
side of daily experiences; mothers, more often, perhaps, who have all
their lives been "nervous" or irritable and easily excited, impress more
or less profoundly these abnormal conditions upon their offspring. Great
singularity of conduct habitually displayed, periods of depression,
irritableness, and nervousness, when crossed with similar characteristics
in the other parent, or other unusual ones, not infrequently develop into
actual insanity in succeeding generations.
A good example of such a tendency is related in the April No. of the
_Journal of Mental Science_, 1881.[11] It began on the male side, the
father being "eccentric" or "peculiar," so much so as to attract the
attention of the village children. The wife had no peculiarities of
sufficient import to be marked. They had four children, three of whom were
affected mentally, one female and two males. The female was "uncommon" and
"slightly weak-minded." One of the males was said to have been
"weak-minded"; the other was "strange-looking," and odd in general
conduct. He married a woman in good health and free from any special
tendency, either mental or physical. There were born eleven children: of
these, five were imbecile; two were idiots, and the remaining four were
sane. Of these four, two had one child each, one of whom died of phthisis,
and the other is at present an imbecile.
A consumptive parent may have children who are free from this particular
form of diathesis, and yet at some period of life may be affected with
insanity; or parents with an insane diathesis may have offspring who are
tainted with scrofula, or phthisis.
Perhaps there are no habits or acquired tendencies which are more surely
transmitted than that of dipsomania or alcoholism; nor are there any which
are more difficult to eradicate when inherited, or acquired in early life.
This diathesis, however, is not always repeated in form, but frequently
passes into other abnormal conditions. Sometimes it manifests itself in
some of the forms of insanity; and again in uncontrollable passions, or
cruelty, or in idiocy, or again in a failure of moral character, or in
epilepsy.
One of the most marked cases which have come under my own observation,
occurred in a family resident in K----. The grandfather and father both
died prematurely from the effects of alcohol, and one of the children, a
lad of seven years, had such a passion for liquor, that he would swallow
at once half a tumbler of wine or whiskey unmixed with water, and could
never be near alcohol in any of its forms without begging for it. This
child, at that age, could not enunciate clearly enough to be understood by
those not familiar with him, and had been unable to learn letters, though
much care had been expended to effect it.
Gall refers to a similar case, in which both the father and grandfather
had prematurely died as drunkards, and a little grandson, exhibited strong
tendencies for alcohol when aged only five years.[12]
"Charles X----, son of an eccentric and intemperate father, manifested
instincts of great cruelty from infancy. He was sent at an early age to
various schools, but was expelled from them all. Being forced to enlist in
the army, he sold his uniform for drink, and only escaped a sentence of
death on the testimony of physicians, who declared that he was the victim
of an irresistible appetite. He was placed under restraint, and died of
general paralysis.
"A man of an excellent family of laboring people was early addicted to
drink, and died of chronic alcoholism, leaving seven children. The first
two of these died at an early age, of convulsions. The third became insane
at twenty-two, and died an idiot. The fourth, after various attempts at
suicide, fell into the lowest grade of idiocy. The fifth, of passionate
and misanthropic temper, broke off all relations with his family. His
sister suffers from nervous disorder, which chiefly takes the form of
hysteria, with intermittent attacks of insanity. The seventh, a very
intelligent workman, but of nervous temperament, freely gives expression
to the gloomiest forebodings as to his intellectual future."[13]
Dr. Morel, after having an opportunity of studying the subject in a very
large number of cases observed among the "_gamins_" of Paris, came to the
conclusion, that the effects of alcohol were of the most terrible nature,
especially when used in boyhood and early manhood, not alone on those
using it, but on their descendants; and that it became manifest in
"physical, moral, and mental degenerations."
Echeverria,[14] who has collected a large number of statistics on the
subject, gives the following in reference to the histories of sixty-eight
males and forty-seven females who had experienced alcoholism in some of
its forms: The number of children born to these persons was four hundred
and seventy-six: and of this total, twenty-three were still-born; one
hundred and seven died from convulsions in infancy; thirty-seven died from
other maladies; three committed suicide; ninety-six are epileptic;
thirteen are congenital idiots; nineteen, maniacal or hypochondriacal;
seven have general paralysis; five, locomotor ataxy; twenty-six, hysteria;
twenty-three, paralysis; nine, chorea; seven, strabismus; three are deaf;
and nineteen are scrofulous and crippled. Of these children, two hundred
and five (205), or nearly fifty per cent., have exhibited drinking
tendencies.
From the above statistics it appears that of all the nervous diatheses
which may be inherited, there are none which are more invariable in their
effects, or more surely disastrous to their unfortunate victims, than that
of alcoholism.
In short, imperfection and abnormality of nerve function in its relation
to mind, especially of intellect and character, of all shades and degrees,
may be inherited as well as acquired; and this is equally true when the
condition has not attained to that of actual disease, but simply a
tendency toward it. And if such tendency should exist on both sides of the
house, it becomes increased in the offspring in geometrical ratio, except
in so far as it may become modified through the influence of counteracting
qualities of character under the law of atavism.
The question now arises: By what measures, or through what influences, if
any, can such proneness to nervous diatheses be avoided? It may be
replied, that there are two channels through which partial relief may
come; but that any substantial results may follow, it will become
necessary that education concerning the laws of heredity shall become more
general, and the importance of right conduct in relation to them impressed
especially on the minds of young persons.
First.--Through the influence of that law of heredity by means of which
there may occur an elimination of weaknesses and proclivities toward
disease. This influence comes from the healthy side of parentage; for
instance, in the case of parents, one of whom has physical or
psychological tendencies toward disease, if the other has a healthy and
vigorous constitution, and is endowed with mental qualities of an opposite
character, these forces of the system may prove to be quite sufficient to
affect or neutralize those which, on the other side of the house, lead
toward disease, and the offspring may have an inheritance nearly, or
quite, free from such influence.
This is not unfrequently witnessed in the case even of the strongest
hereditary diseases, namely those of phthisis and insanity. The offspring
of mothers with proclivities toward either of these diseases, in case the
father is strong, may escape entirely or nearly so; this is very often
true when the well parent has an unusual power of transmitting
race-characteristics, and belongs to a family which has been noted for
longevity during two or three generations.
In this hereditary influence there lies a power of incalculable value to
the human race, a power conducing toward the elimination of morbid
diatheses, which otherwise would go on increasing in almost geometrical
ratio, until families, or even whole communities, would become diseased.
The tendencies toward health, under favorable circumstances, are greater
than toward disease, and, therefore, there exists a probability that
race-characteristics on the healthy side may prevail over those on the
unhealthy side of the house, though this may not always be found to be
true in actual experience.
Through this line of influence, and this only, can there exist any
probability of diminishing the increase of inherited insanity.
Governments and society encourage, and rightly so, the institution of the
marriage relation; the family is the corner-stone of society, and on it
are reared the fabrics of civilization and civil institutions. Probably
from no other practice or custom does there ensue so large effects in the
way of happiness, prosperity, morality, and well-being to the human race,
as from that of marriage; but the conditions of a large part of the
beneficent results of this institution, depend upon freedom from certain
tendencies to disease. Communities and states are composed of units, and
their strength and stability must depend upon that of the individuals
composing them. Quite in the degree that disease or degenerations,
physical or mental, exist in any community, in that measure prosperity and
happiness are diminished; so that from the stand-point of political
economy, even, it becomes of vast importance that the laws of hereditary
influence should be more fully understood.
The instinct of love, however, is so powerful in the vast majority of the
human race, that it overrides almost all other considerations. Persons do
not stop to consider consequences to themselves, or to those who are to
come after; they are borne on by the considerations of a present fancy or
sentiment, and there is reason to fear that any legal enactments, or
regulations, even, in the present state of knowledge on this subject,
would not be worth the paper on which they might be inscribed.
Probably the only thing which can be done is to instruct the public, and
make known, so far as possible, the influences of hereditary tendencies,
publishing them in the higher text-books of schools, and in periodicals.
It might be more clearly understood in reference to marriage, that a
sentimental fancy or a choice founded on the existence of like
characteristics, either mental or physical, not only often proves to be of
little real value in after-life toward securing happiness, but on the
other hand proves, too often, to be the source of vast misery to parents,
their children, and the community in which they may live; that the highest
consideration for the present and future should lead to careful
examination as to inherited characteristics on both sides, and of a
selection which may tend toward elimination, rather than an increase, of
these. It might be more fully understood that, generally, characteristics
of body and mind of _different qualities_, within certain degrees of
limit, contribute toward securing a well-balanced and healthy system, and
also toward a larger degree of happiness in domestic relations; that
acquired diatheses, as well as those inherited, are transmitted to those
who come after; that violations of the laws of healthy brain activity are
almost sure to be punished in the persons of children, whether they have
consisted in immoderate devotion to business or study, or in any of the
physical indulgences. In this way some advance may be hoped for, in
guiding toward that course in which lies the least danger.
The old adage, however, that "the fathers have eaten sour grapes, and the
children's teeth are set on edge," was a truth well understood some
thousands of years ago,--and yet the fathers go on indulging in sour
grapes, because the great truth fails to have taught its lesson, and the
heedlessness of youth requires line upon line, and precept upon precept,
as well as, ofttimes, the sternest of discipline. The future will
doubtless be, in a large degree, as in the past, but we may hope that when
the laws of inheritance are more commonly known, when the learning of them
becomes a part of the general education of the young, their influence will
be more beneficent than at the present time.
Especially may we have reason to expect that such will prove to be the
result in reference to those diatheses which are formed through the
influence of alcohol and tobacco, or by the indulgence of the lower
passions, but the elimination of insanity by these means can, at the most,
be only partial.
The second measure by means of which the unfavorable influences of
heredity may be modified in their subjects, is that of _education_.
I confidently believe the day will come when the first question which will
be asked concerning a child who is to commence an education, will be as to
his or her inheritance; and after obtaining all possible information
concerning this point, it will be a part of the teacher's duty to study
the physical and mental traits and tendencies of each child in the light
of this information. The time will come when the importance of
_individuality_ in education will be so highly appreciated that it will be
considered as essential in all recognized systems. Already there has been
a beginning in this direction, in reference to certain classes of
children. It is not many years since _feeble-minded children_ were treated
as most others now are, and were left to get any little education they
might be able to, with all others. Gradually the importance of individual
education for these weak-minded ones has dawned on the public mind; so
that by systems now in use, many of these, otherwise almost utterly
useless members of the community, have been trained to a degree of
usefulness and self-support.
What has been done for this class should be done for all classes of
persons whose inheritance has in any measure been of a morbid character.
These pyschic neuroses group themselves into certain forms, often at an
early age, and require special care and training from childhood, lest they
develop into actual disease in later life. Among these may be mentioned
the following:
1. The Precocious, }
2. The Passionate and Cruel,}
3. The Timid, }Child.
4. The Wilful, }
5. The Lonely, }
For each of these classes of children special lines of education and
management should be followed, and they should be of such a character as
may tend to repress and correct tendencies of character which in the
future will be almost certain to become morbid. The professional
observations of most physicians who have large experience with diseases of
the nervous system, will suggest the cases of patients who have become
insane, and in whose inheritances and histories some of the above-named
characters have been specially prominent in childhood.
Whatever, therefore, is to be done with a view to modify proclivities
toward those morbid neuroses which result from hereditary influences, or
have been acquired through the force of habit, must be accomplished mainly
through the influence of education, reaching, in different channels, both
parents and children.