ORIGIN OF LIFE.

New Zealand Herald, Volume LIX, Issue 18025, 25 February 1922, Page 1 (Supplement)

ORIGIN OF LIFE.

THE SCIENTIFIC VIEWPOINT.

BS E. B. MACQREGOR, PH.D., J.8.A.1.

Controversy is rife concerning tho above subject. As usual tho protagonists aro the upholders of the Biblical account of creation on the one hand and tho scientists on the other. This article pretends to survey in brief the evidence aduced bv tho scientist sinco the time of Darwin. It i s an axiom that nothing is known or can be known about the way in which tho first living thing made its appearance on the earth; nevertheless, in spite of this absenco of positive knowledge, it is .quite justifiable for the scientist to speculate or to form hypothesis on the subject. It is well hero to differentiate for the uninitiated a mcro "guess" from an " hypothesis." The former has no facts to support it, is the personal opinion and often biassed statement of an individual; whereas an hypothesis is arrived at as a consequence of numerous facts which point in a certain direction, facts congregated from a numbor of sources and vouched for by independent observers. An hypothesis is formulated only after gathering together all the existing shreds of evidonce for and against the supposition; weighing each against its neighbour in order to arrive at a reasonable conclusion as to the truth or falsity of the explanation of tho problem being discussed.

Astronomers have a working hypothesis that " the moon is an extinct world without heat or light of its own, but reflecting that of the sun." No one has actually confirmed or refuted this opinion, nor would it be possible to do so; yet the hypothesis is accepted as,true, or at any rate as infinitely more probable than the gness of the solitary man who might assert that " the moon was made of green choese." The Biological Bias.

And so it is with the origin of life. There ib a vast consensus of evidence (not opinion) pointing in the direction toward a certain hypothesis which is not contradicted by any evidence of fact that has yet been, brought forward. The biologist knows a very wide range of living things —both plants and animals, large and small, Bimple and complex. Some as big as the kauri tree or elephant, with a very elaborate anatomical structure; others like bacteria, of a size so minute as l-25,000th of an inch in diameter, of an extremely simple structure, consisting of a mere speck of living substance, without organs of any kind. Moreover, there is evidence that even smaller living things exist, too minute to be seen by our most powerful microscopes, andcapable of passing through filters which stop the bacteria; wo know them only by the effects they produce. Every living thing to-day is the product of protoplasm—of a previously living thing. The old idea of spontaneous origin or generation of life from non-life—ingrained in tho mind of man since pre-scientific days—has been proved to be impossible of demonstration, and is believed biologically to be a myth. There has been a gradual progress in variety of organism, and in complexity, of structure, as the earth has grown from infancy to maturity. Logically, therefore, we must suppose, that at a still earlier epoch than is represented by any fossiferous rocks, simplicity' became 'simpler and simpler, and that there must have been a simplest beginning to the long series of life forms which have peopled the earth since it was habitable by organisms.

Before Ihe earth was in a fit condition to support living things it was a molten mass of material, surrounded by,gases, very different from. the present atmosphere. As the earth coolod, and so shrank, rain fell, bringing down wift it some of these chemical, substances, which accumulated in depressions, on the surface, forming seas. At first these seas had a high temperature. The rocks were acted upon by the hot water and the other agencies, and various chemical changes must have been going on whilst the earth cooled down. It was only after this that x./ing things could obtain a footing.

Enter the Chemist.

The chemist now comes into the picture. Protoplasm consists of a mixture of very complex bodies known in general terms as proteids, which are found only in association with living things; and all life is associated with proteids. Life and proteids are different expressions of the 'same thing. Proteids consist of carbon, nitrogen, oxygen, hydrogen and sulphur. No chemist has been hitherto able to build up protein from combining these elements in any way, although less complex organic substances, albuminoids, have been synthesised by Emil Fischer. Proteins can be formed to-day only by living things in their bodies. Tho problem, then, of the origin of life is narrowed down to the origin of proteins; but we have no knowledge as to how these were formed in the first instance.

In the last quarter of the 19th century, a physiological chemist, Piluger, announced that living proteins present certain striking analogies with a very unstable fluid, cyanic acid (HCNO), and he showod the importance of the cyanogen radicle (ON) in the chemical processes going on in protoplasm. He suggested that we must look at cyanogen as the starting point of all proteins, and hence of life itself. It is significant that cyanogen and its compounds can be formed only in tho presence of very high temperatures, "and nothing is clearer, - ' says Pfluger, " than the possibility of the formation of cyanogen compounds when the earth was wholly or partially in a fiery state. Fats, also—an essential element of protoplasmcan only be formed in the laboratory by the aid of heat. At a time when the, earth's surface was still incandescent, tho compounds of cyanogen, with their property of ready decomposition, wero forced into combination with various other carbon compounds, and when water was precipitated on the earth's surface, these compounds in their turn entered into combination with water, and its dissolved gases and inorganic solids derived from the rocks. This mixture of materials to form proteins is supposed to be the basis from which living matter, protoplasm, originatcd. " Living Stuff."

What was tho nature of these earliest living things? They must have been of such a nature as to be able to find food in tho surrounding inhospitable water, to feed on inorganic or mineral substances. Liko modem bacteria it is supposed these living things wero neither plant nor animal —just living stuff. This is but one hypothesis as to the origin of life, one that seems to be in accordance with the evidence available from a variety of sources. There are several others, some of which differ from this in details; others are fundamentally different. Of these, one is termed ' creation"—about this tho scientific man is silent; his concern is with such natural processes of which evidence in the form of facts and phenomena are available. Tradition and hearsay have no favour with him But it seems worth while to note that in any theory of the origin of life, the'first living thing must have been formed in some way from particles of in--1 organic substances. And this is what | H dust '-'• consists oL,