Cosmic Radiations and Evolution

Abstract

THERE seem to be no sure grounds for believing that the penetrating radiations are uniformly distributed throughout space. If they are not, and if considerable variations in the strength of those reaching the earth have occurred in the past—possibly referable to translatory movements of the solar system—then serious effects upon organic evolution may have taken place. Millikan estimates their present energy as equal to about one-tenth of that reaching the earth from the luminous radiation of the stars. At present, therefore, the penetrating rays are probably without positive effects upon organic life. It does not follow, however, that a recent decline in strength would be without serious effects.