Those who accept the theory of heredity deny the existence of the human soul as an entity separable from the gross physical organism. Consequently they do not discuss the question whether the individual soul existed in the past or will continue to exist after the death of the body. This kind of question does not disturb their minds. They generally maintain that the individual soul is inseparable from the body or the brain or nervous system; consequently what we call soul or the conscious entity or the thinker is produced along with the birth of the organism or brain, lasts as long as the body lasts and dies when the organism is dissolved into its elements.
But those, on the other hand, who accept the theory of Reincarnation admit the existence of soul as a conscious entity which is independent of the physical organism, that it continues to live after death and that it existed before the birth of the body. The theory of heredity has always been supported by the materialistic scientists, atheists and agnostics of all ages and also by those who believe in the special creation of the first man and woman at a certain definite time and that their qualities, character, life and soul have been transmitted to all humanity through successive generations.
The commonly accepted meaning of the theory of heredity is that all the well-marked peculiarities, both physical and mental, in the parents are handed on to the children; or, in other words, heredity is that property of an organism by which its peculiar nature is transmitted to its descendants.
In the whole history of humanity there has never been a time when this question of heredity has been discussed so minutely and in so many different ways as it has been in the present century. Although this theory was known in the East by the ancient Vedanta philosophers, by the Buddhists of the pre-Christian era and by the Greek philosophers in the West, still it has received a new impetus and has grown with new strength since the introduction of the Darwinian theory of the evolution of species.
Along with the latest discoveries in physiology, biology, embryology and other branches of modern science, the popular simple meaning of heredity–that the offspring not only resemble their parents among animals as well as among men, but inherit all the individual peculiarities, life and character of their parents–has taken the shape of the most complicated and difficult problem which it is almost impossible to solve. Our minds are no longer satisfied with Haeckel’s definition that heredity is simply an overgrowth of the individual, a simple continuity of growth; but we want to know the particular method by which hereditary transmission takes place. We ask, how can a single cell reproduce the whole body of the offspring, its mind, character and all the peculiarities of an organism? Out of the myriads of cells of which a body is composed, what kind of cell is that which possesses the power of reproducing the peculiarities, both mental and physical, which are to be found in the form of the new-born babe?
This is the most puzzling of all the problems which the scientific mind has ever encountered. The fundamental question connected with the theory of heredity is: How can a single cell of the body contain within itself all the hereditary tendencies of the hypothesis of the continuity of the germ-plasm gives an identical starting-point to each successive generation, and thus explains how it is that an identical product arises from all of them. In other words, the hypothesis explains heredity as part of the underlying problems of assimilation and of the causes which act directly during ontogeny. (Vol. I, p. 170.)
According to Weismann, all the peculiarities which we find in an organism are not inherited by the organism from that of the parents, but he says: “Nothing can arise in an organism unless the predisposition to it is pre-existent, for every acquired character is simply the reaction of the organism upon a certain stimulus.” (Vol. I, p. 172.) Therefore the germ-cells do not inherit all the peculiarities of the parents, but possess the predisposition or a potentiality of the tendencies which gradually develop into individual characters.
We will be able to understand his theory better from the following quotations, which give his own words. He says: “I have called this substance ‘germ-plasm,’ and have assumed that it possesses a highly complex structure, conferring upon it the power of developing into a complex organism.” (“Heredity,” Vol. I, p. 170.) Again he says: “There is, therefore, continuity of the germ-plasm from one generation to another. One might represent the germ-plasm by the metaphor of a long, creeping rootstock from which plants arise at intervals, these latter representing the individuals of successive generations.
Hence it follows that the transmission of acquired characters is an impossibility, for if the germ-plasm is not formed anew in each individual, but is derived from that which preceded it, its structure, and, above all, its molecular constitution, cannot depend upon the individual in which it happens to occur, but such an individual only forms, as it were, the nutritive soil at the expense of which the germ-plasm grows, while the latter possessed its characteristic structure from the beginning, viz., before the commencement of growth. But the tendencies of heredity, of which the germ-plasm is the bearer, depend upon this very molecular structure, and hence only those characters can be transmitted through successive generations which have been previously inherited, viz., those characters which were potentially contained in the structure of the germ-plasm. It also follows that those other characters which have been acquired by the influence of special external conditions, during the lifetime of the parent, cannot be transmitted at all.” (Vol. I, p. 273.) In conclusion, Weismann writes: “But at all events we have gained this much, that the only facts which appear to directly prove a transmission of acquired characters have been refuted, and that the only firm foundation on which this hypothesis has been hitherto based has been destroyed.”(Vol. I, p. 461.)
Thus we see how far the theory of heredity has been pushed by the great scientific investigators of the present age. We have no longer any right to believe in the old oft-refuted hypothesis which assumes that each individual organism produces germ-cells afresh again and again and transmits all its powers developed and acquired by the parents; but, on the contrary, we have come to know to-day that parents are nothing but mere channels through which these germ-plasms or germ-cells manifest their peculiar tendencies and powers which existed in them from the very beginning. The main point is that the germs are not created by the parents, but that they existed in previous generations.
Now, what are those germs like? Wherefrom do they acquire these tendencies, these peculiarities? That is another very difficult problem. Dr. Weismann and his followers say that these peculiarities are gained or inherited “from the common stock,” but what that common stock is they do not explain. Where is that common stock and why will certain germs acquire certain tendencies and other germs retain other peculiarities? What regulates them? These questions are not solved. So far we have gathered from Dr. Weismann’s explanation that the parents are not the creators of the germs but, on the contrary, that the germs existed before the birth of the body, before the growth of the body, in previous generations, or in the common stock of the universe. The previous generations are dead and gone, so we may say that they existed in the universe. We cannot now believe the old, crude, often-refuted idea that God creates the germ at the time of birth and puts into it all the powers and peculiarities of the parents.
This theory makes God unjust and partial, so it does not appeal to us any more. We need better and more rational explanations. The one-birth theory, which has been preached by Christian ministers and other religionists for so many years, does not remove the difficulties, does not explain the cause of the inequalities and diversities, does not answer the question whether we acquire all the tendencies and peculiarities of the parents or whether acquired characters cannot be transmitted. We have already seen that these questions are left unsolved by the one-birth theory of Christianity and of Judaism. But this theory of “continuity of the germ-plasm” pushes the question of heredity to the door of Reincarnation. If modern science can explain what that common stock is and why and how these germs retain those peculiarities and tendencies, then the answer will be complete and not until then. The Vedanta philosophy, however, has already explained the cause of the potentiality in the germ of life or “germ-plasm” or germ-cell.