The Destiny of the Body

Chapter VI

THE BASAL IMMORTALITY:

THE EVOLUTION OF DEATH

These glimmerings point to the secret of our birth

And the hidden miracle of our destiny.

(Sri Aurobindo, Savitri, Book II, Canto II, p. 110)

We can resolutely affirm that, in the actual terrestrial conditions of life,

the immortality of the cell is an indubitable fact. ...

And what characterises most a living organism is its potential

immortality and not its death.

(S. Metalnikov, Immortalité et Rajeunissement dans la

Biologie Moderne, pp. 215-216)

In our search for any biological evolutionary clues in support of the idea and ideal of physical immortality, we are agreeably surprised to find a mass of evidence which suggests that natural death is not to be regarded as an intrinsic necessity — the fate of all life. As a matter of fact, "neither senescence nor natural death is a necessary, inevitable consequence or attribute of life. Natural death is biologically a relatively new thing, which made its appearance only after living organisms had advanced a long way on the path of evolution."¹ The evidence supporting this conclusion is manifold and may be considered under several heads:

(i)Potential immortality of unicellular organisms or protozoa;

(ii)potential immortality of germ cells in sexually differentiated organisms;

(iii)potential immortality exhibited by somatic cells in the phenomenon of agamic, or asexual, mode of reproduction;

(iv)phenomenon of autotomy, regeneration and dedifferentiation pointing to the potential immortality of certain groups of somatic cells;

(v)experiments on tissue culture in vitro showing definitively the essential immortality of all types of somatic cells in a multicellular organism or metazoan.

¹ Raymond Pearl, "Biological Aspects of Death," in Encyclopaedia Britannica, Vol. 7, p. 111.

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In the limited span of our essay it is not possible to do adequate justice to the topics enumerated above, nor is it necessary for our present purpose. What interests us most are the results and conclusions that the biologists have arrived at through painstaking researches brilliantly conceived and meticulously carried out in the special fields of senescence and death. Here are the salient results in their bare outline.

We all know that all living organisms, plant or animal, are built up of cells, of a single cell (unicellular organism or protozoan) or of a group of cells (multicellular organism or metazoan).

Now the doctrine of the immortality of protozoa, first enunciated by Ehrenberg and Weismann, has been proved to be a well-attested biological fact, thanks to a series of brilliant investigations conducted in Germany by Woodruff and his pupils, also in Russia by Metalnikov and Caladjief, during the first and second decades of the present century. The essential conclusion of these and similar experiments is that a protozoan or a unicellular organism knows no process of dissolution that can be compared to the phenomenon that we commonly designate as death. As a matter of fact, protozoa, when placed in normally favourable environments, retain indefinitely, through their successive binary fissions, the vital faculty of self-multiplication ad infinitum, without ever betraying any trace of permanent fatigue or senescent degeneracy; and this is so even when these cells are deprived of any rejuvenating process like 'conjugation' or 'endomixis', conditions previously held by Maupas, Calkins and others as absolutely essential and obligatory.

It is thus seen that unicellular organisms like the amoeba possess a kind of potential immortality and are exempt from the nemesis of natural death. As it has been picturesquely put by Prof. Mariano Fiallos-Gil, the protozoan we are viewing through our microscope today has had no dead ancestors; it is the direct descendant of the original of its kind. Omnis cellula ex cellula.

To avoid a possible misunderstanding it must be pointed out that this does not mean that these protozoa possess a charmed life exempt from all destruction and death. As a matter of fact they are being continuously killed by vicissitudes of all types such as accidents, lack of sufficient nutrition, variability of atmospheric conditions and above all by their natural enemies which devour and destroy them.

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But, at the same time, this too is a biological truth that some of these unicellular organisms are totally exempt from natural death and possess to a fantastic degree the creative energy of self-multiplication, so much so that Woodruff had calculated that a single cell would give in seven years' time 4473 generations comprising 2³³⁴⁰ cells which, in the eventuality of all of them remaining alive, would have a total protoplasmic mass whose volume would exceed that of our planet more than 10,000 times.

Leaving the protozoa behind when we come to consider the sexually differentiated multicellular organisms, we encounter two different types of cells: germ cells, carriers of the continuity of the line of the species, and somatic cells, cells constituting the body and its tissues.

Do these cells lodged in a metazoan body possess the same gift of potential immortality as unicellular organisms living in their privileged isolation do ? The answer is a Yes and a No.

First, the germ cells. It is a fact of biological experience that germ cells are indeed equally immortal. "Reduced to a formula," as Prof. R. Pearl has observed, "the fertilized ovum (united germ cells) produces a soma and more germ cells. The soma eventually dies. But some of the germ cells prior to that event produce so-mata and germ cells, and so on in a continuous cycle which has never yet ended since the appearance of multicellular organisms on the earth."¹

But what about the somatic cells? Generally speaking they degenerate and perish after some time thus bringing about as a sequel the somatic death of the individual organism. Indeed, as has been pointed out by the evolutionary biologists, with the establishment of a body as distinct from the germ, natural death has entered the scene. The cells which jointly constitute what has been termed the vegetative individual eventually perish; only the reproductive individuals otherwise known as germ cells maintain continuity between successive generations. Hence the epigram variously expressed albeit in slightly different terms: "Death is the price paid for a body" (Arthur Thomson), or "the penalty paid for a body is death." (Mariano Fiallos-Gil).

But why this strange disability on the part of the somatic cells, especially when all the higher animals have their bodies built up

¹ Raymond Pearl, op. cit.

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out of cells which individually feed and grow and divide exactly as the unicellular organisms do? Does this mean that in some mysterious way a process of seneseent degeneration and the concomitant loss of the power of self-fission have come to inhere in the somatic cells, thus forcing them to lose their potential immortality?

Here too, the biological evidences accruing from different fields of research point to a quite contrary conclusion.

First, some of the lowly-organized groups of metazoa such as the sponges, flatworms and coelenterates (polyps, hydras, jelly fish, etc.) have retained the power of auto-fission leading to the production of new individuals and thus managed to escape natural death. This agamic, or asexual process of reproduction has many different forms such as binary fission, multiple fission, fragmentation, budding, etc.

Binary fission involves an equal, or nearly equal, longitudinal or transverse splitting of the body of the parent into two parts, each of which grows to parental size and form. This method of reproduction is sometimes observed as longitudinal section among metazoans like sea anemones and as transverse fission among planarians. Multiple fission, schizogony, or sporulation produces from a single parent not two but several new individuals. This is common among the Sporozoa like the malarial parasite. Fragmentation is a form of fission (occurring in some metazoans, especially the Platyhelminthes or flatworms, the Nemertinea or ribbon worms, and the Annelida or segmented worms) in which the parent worm breaks up into a number of parts, each of which regenerates missing structures to form a whole organism. Certain starfish, like Linckia, offer a striking example of this process, in which single arms of the parent body may pinch off and regenerate an animal complete in all parts. In budding the new individual arises from a relatively small mass of cells that initially forms a growth or bud in the parental body. It is found as external budding among sponges, coelenterates, bryozoans, flatworms and tunicates, and as internal budding among fresh-water sponges.¹

Two significant conclusions emerge from the study of these

¹ This paragraph is based on the very instructive article "Reproduction" contributed by Prof. Albert Tyler to McGraw-Hill Encyclopedia of Science and Technology, Vol. 14, pp. 448-449.

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agamic modes of reproduction. Firstly, there is no place here for natural death for the metazoan concerned (especially in the case of binary fission). For in the passage from one generation to the next no corpse or residue is left behind. Secondly, these asexual reproductive processes demonstrate the truth of the fact that somatic cells, as well as germ cells, at least in these lowly-organized metazoa, possess the capacity for continued growth and self-multiplication, thus persisting in life for an indefinite duration of time.

This fact of the possession of potential immortality by some somatic cells is also borne out by the remarkable capacity of regeneration or restorative reconstitution exhibited by certain groups of animals. In this process an organism very readily replaces its missing parts lost through some accident or even if seriously injured. Experiments conducted by Wilson and Muller on sponges, by Davidof on ribbon worms, by E. Schultz on fresh-water hydra and by other investigators on some other metazoa have brought to light the highly significant phenomenon that many of the hydroids, annelids, echinoderms and arthropods can replace major portions of their body. In certain instances a small fragment or even a few cells can reconstitute a completely new individual with all its parts intact. Many species of the Amphibia can regenerate a complete limb, a tail, portions of the eye, the lower jaw, and a number of other highly organized structures. What is all the more startling is the fact that, "under certain circumstances, the somatic cells forming the detached portion of the body not only reconstitute a whole organism but can even produce germ cells".¹

A comparative study of the different species which manifest this remarkable capacity for regeneration makes it abundantly clear that natural death of the somatic cells, as a distinct physiological phenomenon, has not intervened all on a sudden in the history of biological evolution. As a matter of fact, death too has passed through a process of evolutionary elaboration. With the gradual loss of the aptitude for self-multiplication and restorative reconstruction, the body-cells have become progressively mortal along the scale of organic evolution. The following table shows clearly this intriguing phenomenon of the development of mortality:

¹ S. Metalnikov, op. cit., p. 110.

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The phenomena we have been studying so far, purporting to show the potential immortality even of somatic cells, are observed only among the lowly-organised organisms. What about the somatic cells constituting the body of complexly organised and highly evolved multicellular organisms including man?

Here too the conclusions arising out of recent biological researches are quite revealing. For a series of experiments on the culture in vitro of cells and tissues, starting with those of Haberland and Harrison and culminating in the epoch-making researches of Carrel and Ebeling, has demonstratively shown that senescence and natural death are in no sense necessary concomitants of cellular life. Indeed the consensus of opinion held by the biologists is that all the essential tissue elements of the metazoan body, including the most highly differentiated and specialized in function, such as nerve cells, muscle cells, heart muscle cells, spleen cells, connective tissue cells, epithelial cells from various locations of the body, kidney cells and others, are potentially immortal and can be made to grow indefinitely when placed and cultured outside the body of the organism in some nutrient medium from where the deleterious products of cell metabolism are regularly removed.

A momentous question arises here in connection with the problem of immortality: How is it that a multicellular body falls a prey to natural somatic death although constituent cells are potentially immortal? Considered from an external point of view the answer lies, according to recent biological findings, in the

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process of differentiation and specialisation of function of these cells and tissues in the body as a whole so much so that any individual part does not find the conditions necessary for its continued existence. As Prof. Raymond Pearl has remarked, in the metazoan body any part is dependent for the necessaries of its existence upon the organization of the body as a whole. "It is the differentiation and specialisation of function of the mutually dependent aggregates of cells and tissues which constitute the metazoan body, that brings about death and not any inherent or inevitable mortal process in the individual cells themselves. When cells show characteristic senescent changes it is perhaps because they are reflecting, in their morphology and physiology, a consequence of their mutually dependent association in the body as a whole, and not any necessary regressive process inherent in themselves."¹ In other words, in the light of present knowledge, we can assert that individual cells never grow old; they are eternally young and potentially immortal, and "the natural death suffered by the somatic cells is by no means an intrinsic necessity but rather a fortuitous circumstance.... As a matter of fact what most characterizes a living organism is its immortality and not its death."²

Thus we come back to the assertion made in the beginning of our essay that the persistent urge of the human race not to accept death as the ineluctable end of man's life and its repeated attempts to conquer it are not such irrational and vain propositions as they might at first sight appear to an uninformed critic. These are rather based upon the subconscious awareness, by the race, of some fundamental truth of embodied life.

¹ Raymond Pearl, op. cit., p. 112.

² S. Metalnikov, op. cit., p. 111. (Italics ours)

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