Science in Christian Perspective



The Origin and Evolution of Life

From: JASA 14 (September 1962):

Most textbooks on biology discuss the characteristics of life and show that non-living "things" do not possess these characteristics in exactly the same way. Thus there is apparently a gulf between the animate and the inanimate. We know that life, whatever it may be, is situated in the material we call protoplasm in the cell. At the recent (1961) A.A.A.S. meetings at Boulder, some biochemists were quoted as saying that the question "What is Life?" is obsolete. They, no doubt, based their belief on the fact that the structure of the selfreplicating DNA molecule in the nucleus of the cell has been almost determined (Watson-Crick model). Reproduction has always been one of the distinguishing characteristics of living things and now that we have reproducing, or self-replicating nucleic acids and proteins, we have solved the riddle of life (so they say). It must be pointed out that this chemical replication goes on only in cells and so it would seem that we are almost back where we started. A classic example quoted is the virus, an organism consisting of a nucleic acid core and a protein sheath. Viruses duplicate themselves prolifically. Harold Blum points out that* "What is to be noted in the present connection is that the virus particle is not a self-replicating machine but depends for its replication upon the metabolism of the host cell-the host cell is always a part of the machine-so, if the term living molecule is used to describe a virus, one runs the risk of having it accepted in a more complete sense than it should be."

Another point of confusion is the equating of the presence of a self-replicating mechanism with its origin. These are really two different aspects of life. The late John von Neumann had no difficulty imagining a self-replicating machine but he could not conceive of a machine that could create itself. Scientists have already created amino acids and are working on the long, hard road to the making of proteins. After they have made complicated proteins, they will not have created life because even the most radical of biochemists do not think of fats, carbohydrates and proteins when divorced from the cell as exhibiting the characteristics of life.

Blum also points out that the origin of life has some relationship to the evolution of life. Natural selection has been constantly evoked as a necessary force in evolution inasmuch as living systems constantly compete and only the fittest survive. Now if we grant that the elemental particles grouped themselves in molecules of a simple sort and eventually into proteins, fats and carbohydrates, it is difficult to imagine this as other than pure chance. In other words, it is hard to place natural selection anywhere in this chemical evolution picture. The elimination of natural selection from some part of the organic cycle does not seem to be a major catastrophy to some of us but the all-or-nothing proponents of Charles Darwin's theory of selection are likely to spend many a sleepless night over it.

*"On the Origin and Evolution of Living Machines "-Amer. Sci. 49:474-501 (1961)