Whence Life?

Give a biologist a pinch of slime mold--primitive but living protoplasm--and he will have no difficulty predicating an evolutionary ascent, from that bit of animate substance, which leads to large, complex and reasoning beings like himself. Yet the prime question remains: How did the first bit of life appear on earth?

To that question there are three possible answers: 1) life was planted on earth by divine power; 2) life emerged from nonliving matter by some pregnant combination of chemical circumstances; 3) life was transported to earth in meteorites or some other carrier, from somewhere else in the universe. Quite satisfactory to many people is the first answer, which renders further inquiry into the problem superfluous. Most biologists, however, prefer to make a choice between the second and the third.

One of those who prefer the second answer is Associate Director A. I. Oparin of the Biochemical Institute of the Soviet Academy of Science. For more than 15 years Dr. Oparin has studied the question in the light of present-day chemical knowledge. Between life and nonlife, in his opinion, there is no sharp boundary. He does not believe that life emerged suddenly and spontaneously from dead matter, but that it developed very gradually after a long preliminary evolution of organic but nonliving substances. In this slow unfolding an observer would have been unable to say just where life began, unless he had concocted an arbitrary and superficial definition. Dr. Oparin has constructed a fairly complete picture of how it all happened, which he published two years ago in Russian. Published last week in the U. S. was The Origin of Life* a translation of Oparin's book made by Dr. Sergius Morgulis, professor of biochemistry at the University of Nebraska.

With the amused impatience of a godless materialist. Soviet Scientist Oparin waves away the various vitalistic theories which hold that life appeared because of some transcendent animating principle which pervades the universe--or that life has always existed. He also refuses to believe that life was carried to earth in meteorites, since existing meteorites show no sign of containing viable organisms. Dr. Oparin also rejects the theory of free spores or other life-bearing particles driven to earth through interstellar space by impacts from radiation. He holds that ultraviolet or cosmic radiation would kill any such life particles beyond the sheltering blanket of the earth's atmosphere.

In his own picture of the evolution of matter, in which the origin and further evolution of life is only a part, Oparin starts with the formation of the planets, pulled out by the tidal action of a passing star. His key element is carbon, which is present in all living matter. Stars are so hot that almost all elements are dissociated into atoms and ions, but carbon compounds have been found spectroscopically in cool stars. In the molten earth, freshly torn from the mother star, carbon would form compounds with heavy metals. These carbides, acted on by superheated steam in the atmosphere, would form hydrocarbons, the simplest of organic compounds as classified by modern chemistry. When the atmosphere became cool enough to condense, torrents of water would rain down to form the hot primordial seas. The action of water on simple hydrocarbons would make more complex ones. For example, acetylene plus water makes acetaldehyde, and two molecules of the latter combine in a new substance, acetaldol. This reaction is the basis for synthetic manufacture of fatty acids.

Living substance is a colloidal aggregate. Colloids are dispersions of one substance in another. The first colloids in the sea were not living substance because they had no shape, no boundary, no individuality. But in some colloids discrete particles are formed called coazervates surrounded by a membrane of water--that is, a definite boundary. These particles attract other organic matter to themselves and thereby grow--a primitive analogue of feeding. An electric current breaks them up in a manner exactly like the disintegration of dead protoplasm. They split in two--a primitive analogue of reproduction. When heated, they form vacuoles (cavities) like those formed in amebas.

From coazervate particles to living cells is only a step, but Dr. Oparin admits it is the most obscure in his chain. He thinks it possible, however, that primitive bacteria may have been intermediate between coazervate particles and well-organized cells. Some bacteria surviving today look like cells in a halfway stage of evolution. Instead of forming a well-defined nucleus the nuclear material is scattered haphazard through the whole body. Dr. Oparin points out other such halfway stages in the important processes of photosynthesis (use of sunlight for metabolism) and fermentation. When these clearly living processes are reached, the rest of organic evolution is a comparatively straightforward story.

Much of the material in The Origin of Life is extremely controversial and it is written in a knotty, semi-technical style that will not make smooth going for lay readers. But it is valuable as the opinion of one man who has made a profound, heavily documented study of one of the most fundamental enigmas which confront mankind.

*Macmillan ($2.75).

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