Norman Horowitz was an American geneticist at the California Institute of Technology who, in the mid 1940s, used the Oparin-Haldane Theory as the basis for his own theory of biochemical synthesis. In doing so, he helped bring to greater prominence the idea of the chemical evolution of life. However, he was not optimistic about the prospects of finding extraterrestrial life, citing the absence of a theory to explain the origin of nucleic acids and proteins. Later, he was the principal investigator on the Viking pyrolytic release experiment. Believing, after the mission, that Viking had ruled out the possibility of martian life he drew the sweeping conclusion that: "Since Mars offered by far the most promising habitat for extraterrestrial life in the solar system, it is now virtually certain that the earth is the only life-bearing planet in our region of the galaxy."^{1, 2}

 

References

1. Horowitz, N. H., et al. "Planetary Contamination I: The Problem and the Agreements," Science, 155, 1501 (1967).
2. Horowitz, N. H., et al. "Microbiology of the Dry Valleys of Antarctica," Science, 176, 242 (1972).