Silent nucleotide substitutions and the molecular evolutionary clock

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Science  28 Nov 1980:
Vol. 210, Issue 4473, pp. 973-978
DOI: 10.1126/science.7434017


Half of the nucleotide substitutions during the evolutionary divergence of genes in animals, bacteria, and viruses are silent changes. These result from an inherent biochemical property of DNA and are fixed by genetic drift. Evolution may be viewed as a device for protecting DNA molecules from extinction.