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Sir Ronald Aylmer Fisher (17 Feb 1890 - 29 Jul 1962) British statistician, geneticist and evolutionary biologist who contributed to mathematical statistics, but also initiated biometric genetics and investigated dominance, backed up with practical breeding experiments. He published his fundamental theorem of natural selection in 1918. Short biography of Sir Ronald Aylmer Fisher >>

Ronald Aylmer Fisher - “Fundamental Theorem of Natural Selection”

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“We may consequently state the fundamental theorem of Natural Selection in the form: The rate of increase in fitness of any organism at any time is equal to its genetic variance in fitness at that time.”

— Ronald Aylmer Fisher

The Genetical Theory of Natural Selection (1930)

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Context of Fisher quote, “Fundamental Theorem of Natural Selection”

As both a statistician as well as a geneticist, in order to derive this statement, R.A. Fisher actually applied a serious mathematical analysis to the parameters involved in natural selection. He considered two groups of individuals bearing alternative genes, and the variations occurring in each group. Any increase in the prevalence of a certain variation implies the genes involved also increase among the individuals in successive generations. Comparing the groups, their two such rates of increase can only be either equal in both groups, or unequal.

Fisher assigned algebraic variables to represent the difference, a, between these rates and α to represent the average effect upon them by gene substitution. The ratio between the appearance of one gene relative to the alternative gene was expressed as the ratio, p : q. The time rate of change was set up in an equation relating these several parameters. Within five lines of equations, Fisher derived a simple equation showing “the rate of increase in fitness due to all changes in gene ratio is exactly equal to the genetic variation of fitness which the population exhibits.” Thus, he demonstrated that the fitness to survive is mathematically related to the genetic variance, as stated in the quote above.

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Nature bears long with those who wrong her. She is patient under abuse. But when abuse has gone too far, when the time of reckoning finally comes, she is equally slow to be appeased and to turn away her wrath. (1882) -- Nathaniel Egleston, who was writing then about deforestation, but speaks equally well about the danger of climate change today.

Carl Sagan: In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion. (1987) ...(more by Sagan)

Albert Einstein: I used to wonder how it comes about that the electron is negative. Negative-positive—these are perfectly symmetric in physics. There is no reason whatever to prefer one to the other. Then why is the electron negative? I thought about this for a long time and at last all I could think was “It won the fight!” ...(more by Einstein)

Richard Feynman: It is the facts that matter, not the proofs. Physics can progress without the proofs, but we can't go on without the facts ... if the facts are right, then the proofs are a matter of playing around with the algebra correctly. ...(more by Feynman)

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