Insanity: Its Causes and Prevention

by Henry Putnam Stearns

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.