The nearly neutral theory of molecular evolution is a modification of the neutral theory of molecular evolution that accounts for slightly advantageous or deleterious mutations at the molecular level. The nearly neutral theory was proposed by Tomoko Ohta in 1973 (including only deleterious mutations) and expanded in the early 1990s to include both advantageous and deleterious nearly neutral mutations. Unlike in Motoo Kimura's original neutral theory—which dealt only with mutations unaffected by natural selection—the nearly neutral theory predicts a relationship between population size and the rate of molecular evolution: in larger populations, genetic drift, which can bring even slightly deleterious mutations to fixation, is a weaker force, so evolution happens more slowly than in smaller populations.
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Famous quotes containing the words neutral, theory and/or evolution:
“The lonely Earth amid the balls
That hurry through the eternal halls,
A makeweight flying to the void,
Supplemental asteroid,
Or compensatory spark,
Shoots across the neutral Dark.”
—Ralph Waldo Emerson (1803–1882)
“By the “mud-sill” theory it is assumed that labor and education are incompatible; and any practical combination of them impossible. According to that theory, a blind horse upon a tread-mill, is a perfect illustration of what a laborer should be—all the better for being blind, that he could not tread out of place, or kick understandingly.... Free labor insists on universal education.”
—Abraham Lincoln (1809–1865)
“Analyze theory-building how we will, we all must start in the middle. Our conceptual firsts are middle-sized, middle-distanced objects, and our introduction to them and to everything comes midway in the cultural evolution of the race.”
—Willard Van Orman Quine (b. 1908)