The Biochemical Evolution of Genetic Material 443 



Further information regarding pre- and postgenic evolution can be expected to be obtained 

 from experiments with polymers, DNA, RNA, and various cell organelles, as well as from 

 experiments involving other planets. It is expected that biochemical and biological evolution 

 will also be found elsewhere in the universe. 



REFERENCES 



Abelson, P. H., "Extra-Terrestrial Life," Proc. Nat. Acad. Sci., U.S., 47:575-581, 1961. 



Blum, H. F., "On the Origin and Evolution of Living Machines," Amer. Sci., 49:474-501, 

 1961. 



Calvin, M., "The Origin of Life on Earth and Elsewhere," Ann. Int. Med., 54:954-976, 1961. 



Clark, F., and Synge, R. L. M., (Eds.), The Origin of Life on the Earth, New York, Pergamon 

 Press, 1959. 



Huang, S.-S., "Life Outside the Solar System," Scient. Amer., 202 (No. 4):55-63, 1960. 



Lederberg, J., "Exobiology: Approaches to Life Beyond the Earth," Science, 132:393-400, 

 1960. 



Lederberg, J., and Cowie, D. B., "Moondust," Science, 127:1473-1475, 1958. 



Miller, S. L., and Urey, H. C, "Organic Compound Synthesis on the Primitive Earth," 

 Science, 130:245-251, 1959. 



Oparin, A. L, Tlie Origin of Life on the Earth, 3rd Ed., New York, Academic Press, 1957. 



Penrose, L. S., "Self-Reproducing Machines," Scient. Amer., 200 (No. 6):105-114, 1959. 



Rose, H. H., A Synthesis of Evolutionary Theory, Englewood Cliffs, N.J., Prentice-Hall, 1962. 



Sagan, C, "The Planet Venus," Science, 133:849-858, 1961. 



Sagan, C, "On the Origin and Planetary Distribution of Life," Rad. Res., 15:174-192, 1961. 



Sinton, W. M., "Further Evidence of Vegetation on Mars," Science, 130:1234-1237, 1959. 



Tax, S. (Ed.), The Evolution of Life, Vol. 1 of Evolution after Darwin, Chicago, University 

 of Chicago Press, 1960. 



Van Kammen, A., "Infectious Ribonucleic Acid in the Ribosomes of Tobacco Leaves 

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See Supplement VII. 



QUESTIONS FOR DISCUSSION 



48.1. Which do you think came first in evolution, the gene or what we now consider "gene 

 product"? Explain. 



48.2. Do you consider it a fact that the genetic material on earth has undergone a biochemical 

 evolution? A structural evolution? A functional evolution? Why? 



48.3. Do you believe there are "superhumans" on other planets? Why? 



48.4. Do you suppose, in the future, that we will need to be just as careful to avoid the 

 accidental transplantation of genotypes from other planets to our own, as we now 

 are to avoid the reverse? Why? 



48.5. In what respects would you expect the environment of Venus to be changed by explan- 

 tation of a photosynthesizing microorganism to its atmosphere? 



48.6. What kind of information would you seek to discover from landings on the moon? 

 Mars? Venus? 



48.7. What characteristics would you expect genes from other planets to have? 



