Early life history: A computer analysis

Abstract

Theoretical computer calculations, based in part on measurements of ‘young’ stars obtained with an orbiting telescope, may require a reexamination of some of the basic ideas about the composition of the earth's early atmosphere and the origin of life. According to Joel S. Levine, atmospheric geophysicist at the Langley Research Center, ‘the overwhelming majority of chemical evolution experiments since the first in 1952 may have been conducted with the wrong atmospheric mixture.’Astronomical measurements indicate that considerably more ultraviolet (UV) radiation may have been emitted by the young sun in comparison to that emitted by the present sun. Therefore, high levels of such radiation from the young sun, potentially harmful to life, would have been striking the earth at the very time life was being formed.Recent photochemical calculations by Levine and others at Langley state that at the time complex organic molecules (the precursors of living systems) were first formed from atmospheric gases the earth's atmosphere was not composed primarily of methane, ammonia, and hydrogen, as was previously supposed; instead, it was composed of carbon dioxide, nitrogen, and water vapor, all resulting from volcanic activity. The calculations indicate that both methane and ammonia were extremely short‐lived and that such an atmosphere was photochemically unstable if it existed at all.