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The Animate and the Inanimate William James Sidis |
CHAPTER XI
THEORIES OF THE ORIGIN OF LIFE
According to our hypothesis, life always has existed and always will exist under all conditions in some form, though that form may be quite different from any form of life that comes within our experience. If we trace back the ancestry of present-day life, we will always be able to trace it back to some life, though it may be in such a form that it might be extremely difficult to recognize it as life. Thus, there never was a time when life started on the earth; it merely developed into its present complex form from some simpler form that existed on earth when the earth was in a molten or even in a vaporous condition; still farther back, it can be traced to some extremely simple form of life that existed as far back as the nebula out of which the solar system originated; we shall later attempt to trace it back beyond the nebula.
Our theory of the origin of life is thus that there was no origin, but only a constant development and change in form. This belongs to the class of theories known as the Biogenetic theories, as contrasted to the Abiogenetic theories, which assume that at some previous time life did not exist, and that under certain special circumstances that existed when the earth was in a heated condition the necessary elements came together somehow and assembled themselves into a living body from which all other living bodies are descended. The nature of this automatic assemblage of constituents remains, of course, rather mystical; not to speak of the fact that the assumption of spontaneous generation is rather contrary to observed facts.
Such abiogenetic theories have very frequently been advanced, especially since every now and then there is a recrudescence of the belief that spontaneous generation of life is possible under present circumstances, that life could be produced in the laboratory, in spite of all observed facts to the contrary. Haeckel represents this abiogenetic theory in its most general form; that, when water first liquified on the earth, its reaction on various substances then present produces proteid, which was the original life from which all life has descended.
How this proteid was formed remains a mystery. We have, however, a more detailed explanation in Pflüger's theory, which is to the general effect that the original combination was that between carbon and nitrogen, forming cyanogen, which in its turn united with other substance, especially the hydrogen and oxygen of water, to form more and more complex cyanogen or other similar carbon-nitrogen compounds, such combination forming as a final result proteid, the chemical basis of which would thus be the cyanogen radical, CN. Here we have a very likely explanation. In the first place, even many simple cyanogen compounds have many chemical reactions very similar to those of proteid; in the second place, whereas proteid has, in itself, been found to constitute a very great poison, is it also known that cyanogen is one of the most powerful poisons known, and that its compounds are, in general, extremely poisonous, though in certain combinations found in living bodies (e. g., almonds) such compounds seem to be quite harmless.
One difficulty with this is that this idea of spontaneous generation is somewhat contrary to observed facts; there is no instance observed of such a thing as spontaneous generation of life. But the main difficulty is to explain the formation of cyanogen and especially of its compounds from their elements. It is perfectly true, as alleged, that carbon and nitrogen being together at a high temperature will form a little cyanogen, but, with the large amount of oxygen present, this cyanogen could not last long, since cyanogen is a very endothermic substance, and under the second law of thermodynamics, it will reduce to the combination that has less chemical energy, losing the difference in the form of heat; resulting in carbon dioxide and nitrogen as a product. Accordingly we must suppose some peculiar sort of carbon and nitrogen that will not only unite into cyanogen, but which will form such a peculiar form of cyanogen that, instead of oxidizing on contact with oxygen (as ordinary cyanogen would), it not only holds itself aloof from oxidation but even forms more complex and more endothermic compounds. We must suppose some form of carbon and nitrogen which would reverse the ordinary chemical reactions under those circumstances; or, since those reactions are based ultimately on the second law of thermodynamics, we must suppose that there was at that period of the earth's history some carbon and nitrogen that possessed the ability to reverse the second law of thermodynamics. If we suppose that, our theory of life can easily harmonize with the Pflüger idea as to the origin of organic life from cyanogen compounds. In fact, as we have seen, our theory of life is such that we would theoretically suppose that living organisms would have a chemical construction based on the cyanogen radical, thus falling in exactly with Pflüger's idea that life on the earth originated in cyanogen and its compounds.
So much for the abiogenetic theories. Turning now to the biogenetic theories, we can hardly find them much more satisfactory. We have, for instance, Preyer's theory that the earth itself, in the heated state, was itself an immense living organism, from which all living organisms existing at present are descended; all inorganic matter on the earth being merely the rejected excretions of the former living earth, while the living substance came more and more to resemble protoplasm.
Absurd as this theory may sound, there is nothing impossible about it. However, the astronomy of the proposition is rather poor. There is no reason to believe that the earth, in a heated state, was in any different condition from all other known bodies which we find in a similarly heated state (e. g., the major planets and the sun); and these heavenly bodies are hardly in a condition which could by any stretch of imagination be called living. However, if by living is meant that there is a potentiality of the generation of life, of course the earth in a heated condition must have come under that heading. But since the heated planets have no particular resemblance to life, what is more likely is, that on the earth in a heated state, there was life, and there was such life even in the nebula, almost as different from the life that we know at present as the kind of earth-organism that Preyer supposes, but having some properties in common with present life. This is precisely what our theory of life would lead to.
We come now to the biogenetic theory most commonly advanced, one which numbers among its supporters Helmholtz and Sir William Thompson. This is the so-called theory of cozmozoa, otherwise known as the theory of seed-bearing meteors. This theory is to the effect that two planets, at least one of which had developed life on it, came into collision, so that each of the planets was broken into small pieces which were scattered all over in different directions. Some of the pieces of the life-bearing planet, in the form of meteorites, passed another, always bearing within them the seeds of life. These meteorites finally came into the solar system and entered the earth's atmosphere, then striking the earth and planting these seeds of life on the earth, which afterwards developed into the various forms of life that now exist.
This theory sounds very plausible, but again it is based on very poor astronomy. The common meteors, or shooting-stars, which are the actual bodies that seem to have passed from one system to another in this manner, never actually reach the earth's surface, but are completely burned up before they have penetrated very far into the atmosphere. The larger bodies that actually reach the earth's surfaces are the so-called meteorites which are as much parts of the solar system as the planets, and even move round the sun in the same direction as the planets; which are, in fact, simply stray asteroids. Tracing life to such bodies is not tracing it to any other stellar system, but merely to the solar system, and makes it more impossible than ever to trace back where these supposed seeds of life from, or how they got into the meteorite. There is, of course, nothing to prove that such a meteorite as this hypothesis assumes could not be formed, or that it could not thus transplant life from one planet to another. But, since such meteorites as are large enough to reach the earth's surface and at the same time are not members of the solar system do not seem to be a regular occurrence, there being no known instance of such a body, it would seem that such as occurrence is a very rare one, if indeed it can happen at all that any life in its present form could survive such a collision or such a long trip through space. Should two planets happen to collide as the hypothesis assumes, and should any life on those planets survive the collision, the chances are almost nil that, in the case when it happens, any of the pieces of wreckage would strike another planet at all, much less that it would strike one at the very period when that planet was ready to receive the very form of life carried by the meteorite. Thus not only is the hypothesis improbable per se, it is also contrary to any observed facts, since the actual bodies that could be supposed to come from other stellar systems are, as far as observation goes, so small that they are burned by friction with the atmosphere long before they can reach the surface of the earth.
It might be interested to note that, in the time of Helmholtz and Thompson, the distinction between the meteors or shooting-stars that come from other stellar systems, and the meteorites or aerolites which form part of the solar system, was a distinction which had not yet been clearly drawn.
We thus come to the conclusion that the theory of Cosmozoa is entirely unacceptable in view of present facts, which Preyer's theory of the earth-organism can only be accepted in the extremely modified form that the earth, in its molten and vaporous states, contained life (instead of having been alive, as Preyer himself would have it). Thus we come to the conclusion that life is as eternal as the inanimate, and is to be found as universally, under as varying conditions, as inanimate phenomena. On the other hand, we can also accept the Pflüger idea that life as it exists on this earth originated from the formation of cyanogen and its compounds.
Our theory of the origin of life is really Biogenetic, in that it supposes that all life originated from life for an eternity past; but, on the contrary, inasmuch as the past life from which the present life is derived was in an almost unrecognizably different form from that in which life at present appears, it supplies a basis for the Abiogenetic theories of the origin of life from non-living organisms which are, according to our theory, inorganic life.