American Scientist

To the Editors:

“The Origin of Life” article by James Trefil, Harold Morowitz and Eric Smith (May–June 2009) contains the most comprehensive current considerations regarding this compelling topic. The authors effectively counter the Cech and Altman “RNA World” proposal of the 1980s. Their treatments convincingly support the widely held “Metabolism First” theory of life’s origin. I wish to recall a proposed influence on this origin that is missing from today’s literature on the topic. Morowitz et al. suggest that life “can be expected to develop on any planet whose chemistry resembled that of the early Earth.” I have proposed that such a planet must rotate. While engaged in defense research at the California Institute of Technology during World War II, I studied the origin of life as a sideline. I postulated that the daily temperature cycles accompanying Earth’s rotation must have been a prominent factor in the origin and that these cycles tended to favor the formation and maintenance of the most stable association complexes. In a Philosophy of Science article in 1945, I suggested that the importance of the proposed actions could be assessed by laboratory experiments with suitable material aggregates exposed to oscillations of temperature or radiant energy. In 1953, the related Miller-Urey experiment was published. Morowitz et al. tacitly include the existence of temperature cycles by stating “that life will appear on any planet that reproduces the environmental and geological conditions that appeared on the early Earth.” But none of their conclusions, nor those of other researchers, explicitly recognize this proposed role of cycling temperatures.

J. Lee Kavanau
Los Angeles, CA