Cause of Evolution?

The most provocative theory in contemporary science—that cosmic rays are the inspirers of biological evolution—was discussed this week by Dr. Gioacchino Failla in the abstruse Journal of Applied Physics. His purpose was to inform physicists about the biological effects of some forms of radiation with which they work—notably gamma rays, X-rays and cosmic rays.

These rays are really bombardments of tiny electrical particles, which easily penetrate matter. There they dislodge electrons from atoms and molecules, making some positive, some negative in charge—i.e., ionized. Ionizing radiations damage living matter: many pioneer workers with radium were maimed and killed.

In 1927 Hermann Joseph Muller, at the University of Texas, using Drosophila (fruit flies), proved that X-rays also have profound genetic effects. Piercing the nucleus of a living cell, they can destroy or rearrange the genes which determine the inherited characteristics of all new life. But, observes Dr. Failla, "All living organisms are subjected to ionizing radiations throughout their life." Chief sources are 1) potassium, a mildly radioactive element found in all cells, 2) cosmic rays, which constantly penetrate each human being.

These natural ionizing rays, Muller theorized, may well cause the small percentage of "spontaneous" mutations (marked inheritable deviations from the ancestral norm) in all forms of life. The success of some mutations in the struggle for existence largely accounts for evolution, which has proceeded through the ages from protozoa to lizard to man seemingly in spurts rather than at a steady pace. The spurts and lags may correspond to varying intensity of cosmic ray showers.

Astronomer Harlan True Stetson of M.I.T. and other scientists think this theory is entirely reasonable. But the combined influence of potassium and cosmic rays does not now appear adequate to explain spontaneous mutations. It is possible, notes Dr. Failla, that relatively "very small amounts of radiation are much more genetically effective than large ones."