Saturday, April 12, 2014
Who gave the right for Eugenicists to try and play God with GOD's children. These are children created by God and not to have their fate limited in the eyes of men of medical science!
The right understanding of this famous problem is therefore fraught with the most important consequences to eugenics. The huge mass of experimental evidence that has been accumulated during the last quarter of a century has, necessarily, been almost wholly based on work with plants and lower animals.
Even though we can not attempt to present a general review of this evidence, for which the reader must consult one of the standard works on biology or genetics, we shall point out some of the considerations underlying the problem and its solution.
In the first place, it must be definitely understood that we are dealing only with specific, as distinguished from general, transmission.
As the germ-cells derive their nourishment from the body, it is obvious that any cause profoundly affecting the latter might in that way exercise an influence on the germ-cells; that if the parent was starved, the germ-cells might be ill-nourished and the resulting offspring might be weak and puny. There is experimental evidence that this is the case; but that is not the inheritance of an acquired character.
If however, a white man tanned by long exposure to the tropical sun should have children who were brunettes, when the family stock was all blond; or if men whose legs were deformed through falls in childhood should have children whose legs, at birth, appeared deformed in the same manner;
then there would be a distinct case of the transmission of an acquired
characteristic. "The precise question," as Professor Thomson words it, "is this: Can a structural change in the body, induced by some change in use or disuse, or by a change in surrounding influence, affect the germ-cells in such a specific or representative way that the offspring will through its inheritance exhibit, even in a slight degree, the modification which the parent acquired?" He then lists a number of current misunderstandings, which are so widespread that they deserve to be considered here.
(1) It is frequently argued (as Herbert Spencer himself suggested) that unless modifications are inherited, there could be no such thing as evolution. Such pessimism is unwarranted. There is abundant
explanation of evolution, in the abundant supply of germinal variations which every individual presents.
(2) It is common to advance an interpretation of some observation, in support of the Lamarckian doctrine, as if it were a fact. Interpretations are not facts. What is wanted are the facts; each
student has a right to interpret them as he sees fit, but not to represent his interpretation as a fact.
It is easy to find structural features in Nature which may be interpreted as resulting from the inheritance of acquired characters; but this is not the same as to say and to prove that they have resulted from such inheritance.
(3) It is common to beg the question by pointing to the transmission of some character that is not proved to be a modification. Herbert Spencer cited the prevalence of short-sightedness among the "notoriously studious" Germans as a defect due to the inheritance of an acquired
character.
But he offered no evidence that this is an acquirement rather than a germinal character. As a fact, there is reason to believe that
weakness of the eyes is one of the characteristics of that race, and
existed long before the Germans ever became studious--even at a time when most of them could neither read nor write.
(4) The reappearance of a modification may be mistaken for the
transmission of a modification. Thus a blond European family moves to
the tropics, and the parents become tanned. The children who grow up
under the tropical sun are tanned from infancy; and after the
grandchildren or great-grandchildren appear, brown from childhood, some
one points to the case as an instance of permanent modification of skin-color.
But of course the children at the time of birth are as white as their distant cousins in Europe, and if taken back to the North to be brought up, would be no darker than their kinsmen who had never been in the tropics. Such "evidence" has often been brought forward by careless observers, but can deceive no one who inquires carefully into the facts.
(5) In the case of diseases, re-infection is often mistaken for
transmission. The father had pneumonia; the son later developed it; ergo, he must have inherited it. What evidence is there that the son in this case did not get it from an entirely different source? Medical
literature is heavily burdened with such spurious evidence.
(6) Changes in the germ-cells along with changes in the body are not relevant to this discussion. The mother's body, for example, is poisoned with alcohol, which is present in large quantities in the blood and therefore might affect the germ-cells directly. If the children
subsequently born are consistently defective it is not an inheritance of
a body character but the result of a direct modification of the germ-plasm. The inheritance of an acquired modification of the body can only be proved if some particular change made in the parent is inherited as such by the child.
(7) There is often a failure to distinguish between the possible
inheritance of a particular modification, and the possible inheritance of indirect results of that modification, or of changes correlated with it. This is a nice but crucial point on which most popular writers are confused. Let us examine it through a hypothetical case. A woman, not herself strong, bears a child that is weak. The woman then goes in form athletics, in order better to fit herself for motherhood; she
specializes on tennis.
After a few years she bears another child, which is much stronger and better developed than the first. "Look," some one will say, "how the mother has transmitted her acquirement to her offspring." We grant that her improved general health will probably result in a child that is better nourished than the first; but that is a very different thing from heredity.
If, however, the mother had played tennis until her right arm was over-developed, and her spine bent; if these characteristics were nowhere present in the ancestry and not seen
in the first child; but if the second child were born with a bent spine
and a right arm of exaggerated musculature, we would be willing to
consider the case on the basis of the inheritance of an acquired
character. We are not likely to have such a case presented to us.
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