CONSANGUINEOUS MARRIAGES.
Something relating to the subject of consanguineous marriages, which are
not uncommon in some communities, may properly be added here, as bearing
on this subject, and as in some measure supplemental to the preceding
chapter.
There have been differing opinions among physicians in reference to the
effects upon offspring, both physical and mental, of consanguineous
marriages. Several French physicians have written able articles, the
tendency of which is to indicate that such marriages result in deaf-mutism
and idiocy. It has been claimed that the statistics of asylums for the
deaf and dumb, the blind, and the idiotic, give color to such conclusions.
Among those who have more or less fully and carefully examined the
subject, with results tending to confirm such a theory may be mentioned
Dr. Bemis, of Kentucky; Dr. Chazarain, of Bordeaux; and Mr. Boudin.
On the other hand, there have been adduced numerous statistics which
indicate that no unfavorable results follow such marriages, which can
fairly be considered as arising from consanguinity. Without entering fully
into the details of this discussion, I propose simply to indicate certain
principles and facts which have been pretty definitely settled, and such
inferences as may appear to be entirely legitimate, and also have a
bearing on our subject. For a more exhaustive examination of the question,
I may refer the reader to Ribot, on "Heredity," and Miles, on
"Stock-Breeding."
1. The ancient Egyptians, the Persians, the Syrians, and some other
nations, were accustomed to practise consanguineous marriages. Brothers
married sisters, cousins married cousins in all degrees of relationship,
and sometimes even fathers cohabited with their own daughters. Dr.
McGraw[15] says "there can be no doubt that close and continual
interbreeding has taken place time and again, without evident injurious
consequences, among simple and uncultivated communities. Notable examples
are the Pitcairn Island settlements, formed from the close
in-and-in-breeding of the progeny of four mutineers from the ship
_Bounty_, and nine native women; the small community of fishermen, near
Brighton, England; the numerous small and isolated villages of Iceland;
and the Basque and Bas-Breton settlements among the Pyrenees. We must
admit, from overwhelming evidence, that under such circumstances as the
settlements just mentioned afforded, consanguinity among married people
does not necessarily cause evil results to the progeny. If it be asked how
it would be with men of more civilized habits, we are unfortunately
obliged to confess that there are no statistics whatever on the subject
which can give us any exact and trustworthy information."
2. Experiments in interbreeding of cattle go to prove that in some cases,
at least, this may be continued for many generations with no unfavorable
results. A friend of mine has bred in-and-in a herd of Jersey cattle, as
close as a father to his progeny, for five generations, and with
apparently good results.
I have a flock of India pigeons which have been in-bred for fifteen years
to my own knowledge, and apparently with no deterioration. They are still
strong, vigorous, and prolific.
There is a herd of wild cattle now in the Chillingham Park, England, which
has been confined there for several hundred years, and strictly isolated.
No new strains have been introduced, and the herd still remains hardy and
healthy.
On the other hand, there exists a general impression among physicians,
based upon experience and observation of a general character, that
marriages of consanguinity result, more often than other marriages, in
unfavorable effects upon offspring; and the statistics collected by Dr.
Bemis and others appear, on first examination, to confirm such
conclusions.
The majority of farmers and stock-breeders in this country act upon the
theory that it is important and, indeed, necessary, in order to maintain
herds and flocks in a healthy condition, to frequently introduce other
strains of blood; and the farmer who should fail to do this in reference
to his cattle, his swine, and fowls, would be entitled to little sympathy
in case his animals should degenerate in any measure physically, or become
less prolific.
Now, the well-established principles of heredity appear to confirm, in a
general way, both these views. The qualities of parents whether healthy or
unhealthy are transmitted to offspring; and if all herds of cattle and
swine and flocks of fowls were in a strictly healthy condition, there
would exist no reasons why they might not remain so indefinitely, so far
as interbreeding is concerned.
The conditions of animal life, however, under the influence of
civilization, are certainly more unfavorable to health than when in a
native condition. This is especially true of those classes upon which we
depend for labor. The change from animal life on the broad prairies and
woods of a temperate zone, to life in stables of crowded cities and yards
of farmers, many of which are in any thing but a sanitary condition, and
to the experience of daily exposure and labor, and ofttimes to ill
treatment and improper food, induces disease no less surely among animals
than among the human race.
If either men or animals were in a condition of perfect health, there
would be no unfavorable results from marriages of consanguinity, or other
marriages, as there would exist no imperfections, either physical or
mental, to be transmitted. No such persons, however, are found. All are
tainted with the seeds of disease to a greater or less extent, and health
is a question of degree. If, now, two persons of a phthisical or insane
diathesis contract marriage, the tendency toward such a diathesis will be
greatly increased in the offspring. If this tendency in each parent be
represented by two, then it will be two multiplied by two in the
offspring, except so far as it may be modified through the influence of
atavism. This would be the case without reference to the question of
consanguinity.
But blood-relatives are vastly more likely to inherit a similar
diathesis--indeed, are quite sure to do so, if it be one of unhealthy
character,--and the atavic influences would also be similar; so that any
counteracting effect through this influence would be much less between
blood-relations than with others, and would probably be the greatest when
no such relation exists.
Here, then, becomes apparent the danger arising from consanguineous
marriages, _i. e._, that of perpetuating and intensifying unfavorable
physical and mental traits, which may be alike on both sides. Where no
such relation exists, there is a great probability that other
counteracting qualities of character and hereditary influences may modify
and even remove weaknesses, while, with such a relation existing, there is
every probability that weaknesses or tendencies toward disease, both
physical and mental, whether inherited or acquired, will become greatly
increased.
Therefore, as there exist in many families, undesirable traits of
character, both physical and mental, a removal or diminution of which is
desirable; and as there is a greater probability that this can be more
surely done, of whatever nature they may be, by introducing other and
opposing tendencies from unrelated families, it would appear to be highly
important, as a rule, to discountenance marriages of persons who are
related to each other by ties of blood.