Frases de John Burdon Sanderson Haldane

John Burdon Sanderson Haldane Foto
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John Burdon Sanderson Haldane

Fecha de nacimiento: 5. Noviembre 1892
Fecha de muerte: 1. Diciembre 1964

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John Burdon Sanderson Haldane fue un genetista y biólogo evolutivo británico. Junto con Ronald Fisher y Sewall Wright, fue uno de los fundadores de la genética de poblaciones.

Su principal contribución fue una serie de artículos compilados en A Mathematical Theory of Natural and Artificial Selection y resumidos en The Causes of Evolution . En ellos Haldane estudiaba dos asuntos fundamentales para la matematización de la teoría evolutiva: la dirección y las tasas de cambio de frecuencias génicas y la interacción de la selección natural con la mutación y la migración. No obstante, Haldane admitía varias causas evolutivas, como la saltación y la ortogénesis, independientemente del protagonismo de la selección natural

El trabajo de Haldane se convirtió en una de las principales contribuciones a la teoría evolutiva sintética o síntesis moderna, que restableciera la selección natural como el mecanismo esencial del cambio evolutivo, explicándolo en términos de las consecuencias matemáticas de la genética mendeliana.

Haldane acuñó también el llamado principio de Haldane, el cual afirma que el tamaño de los seres vivos define la complejidad de sus órganos internos.

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Frases John Burdon Sanderson Haldane

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„If two animals have a common ancestor, their parasites are likely to be descended from those of the ancestor.“

— J. B. S. Haldane
Context: Comparative parasitology supports the evolutionary hypothesis. If two animals have a common ancestor, their parasites are likely to be descended from those of the ancestor. This principle has been applied with considerable effect to the classification of frogs and other groups. Introduction, p. 9.

„Our ancestors were mostly rather rare creatures.“

— J. B. S. Haldane
Context: Wright's theory certainly supports the view taken in this book that the evolution in large random-mating populations, which is recorded by palaeontology, is not representative of evolution in general, and perhaps gives a false impression of the events occurring in less numerous species. It is a striking fact that none of the extinct species, which, from the abundance of their fossil remains, are well known to us, appear to have been in our own ancestral line. Our ancestors were mostly rather rare creatures. " Blessed are the meek : for they shall inherit the earth." Appendix, pp. 213-214.

„If much of the investigation here summarised has only proved the obvious, the obvious is worth proving when this can be done. And if the relative importance of selection and mutation is obvious, it has certainly not always been recognised as such.“

— J. B. S. Haldane
Context: Unaided common sense may indicate an equilibrium, but rarely, if ever, tells us whether it is stable. If much of the investigation here summarised has only proved the obvious, the obvious is worth proving when this can be done. And if the relative importance of selection and mutation is obvious, it has certainly not always been recognised as such. Appendix

„If human evolution is to continue along the same lines as in the past, it will probably involve a still greater prolongation of childhood and retardation of maturity. Some of the characters distinguishing adult man will be lost. It was not an embryologist or palaeontologist who said, "Except ye . . . become as little children, ye shall not enter into the kingdom of heaven."“

— J. B. S. Haldane
Context: If human evolution is to continue along the same lines as in the past, it will probably involve a still greater prolongation of childhood and retardation of maturity. Some of the characters distinguishing adult man will be lost. It was not an embryologist or palaeontologist who said, "Except ye... become as little children, ye shall not enter into the kingdom of heaven." Ch. V What is Fitness?, p. 150.

„Another possible mode of making rapid evolutionary jumps is by hybridisation.“

— J. B. S. Haldane
Context: Where natural selection slackens, new forms may arise which would not survive under more rigid competition, and many ultimately hardy combinations will thus have a chance of arising.... Thus the distinction between the principal mammalian orders seems to have arisen during an orgy of variation in the early Eocene which followed the doom of the great reptiles... Since that date mammalian evolution has been a slower affair, largely a progressive improvement of the types originally laid down in the Eocene. Another possible mode of making rapid evolutionary jumps is by hybridisation.... hybridisation (where the hybrids are fertile) usually causes an epidemic of variation in the second generation which may include new and valuable types which could not have arisen within a species by slower evolution. Ch. IV Natural Selection, pp. 104-106.

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„Where natural selection slackens, new forms may arise which would not survive under more rigid competition“

— J. B. S. Haldane
Context: Where natural selection slackens, new forms may arise which would not survive under more rigid competition, and many ultimately hardy combinations will thus have a chance of arising.... Thus the distinction between the principal mammalian orders seems to have arisen during an orgy of variation in the early Eocene which followed the doom of the great reptiles... Since that date mammalian evolution has been a slower affair, largely a progressive improvement of the types originally laid down in the Eocene. Another possible mode of making rapid evolutionary jumps is by hybridisation.... hybridisation (where the hybrids are fertile) usually causes an epidemic of variation in the second generation which may include new and valuable types which could not have arisen within a species by slower evolution. Ch. IV Natural Selection, pp. 104-106.

„We have now to ask whether God made the tapeworm. And it is questionable whether an affirmative answer fits in either with what we know about the process of evolution or what many of us believe about the moral perfection of God.“

— J. B. S. Haldane
Context: I have given my reasons for thinking that we can probably explain evolution in terms of the capacity for variation of individual organisms, and the selection exercised on them by their environment.... The most obvious alternative to this view is to hold that evolution has throughout been guided by divine power. There are two objections to this hypothesis. Most lines of descent end in extinction, and commonly the end is reached by a number of different lines evolving in parallel. This does not suggest the work of an intelligent designer, still less of an all mighty one. But the moral objection is perhaps more serious. A very large number of originally free-living Crustacea, worms, and so on, have evolved into parasites. In doing so they have lost, to a greater or less extent, their legs, eyes, and brains, and have become in many cases the course of considerable and prolonged pain to other animals and to man. If we are going to take an ethical point of view at all (and we must do so when discussing theological questions), we are, I think, bound to place this loss of faculties coupled with increased infliction of suffering in the same class as moral breakdown in a human being, which can often be traced to genetical causes. To put the matter in a more concrete way, Blake expressed some doubt as to whether God had made the tiger. But the tiger is in many ways an admirable animal. We have now to ask whether God made the tapeworm. And it is questionable whether an affirmative answer fits in either with what we know about the process of evolution or what many of us believe about the moral perfection of God. Ch. V What is Fitness?, pp. 158-159.

„Science is as yet in its infancy, and we can foretell little of the future save that the thing that has not been is the thing that shall be; that no beliefs, no values, no institutions are safe.“

— J. B. S. Haldane
Context: Science is as yet in its infancy, and we can foretell little of the future save that the thing that has not been is the thing that shall be; that no beliefs, no values, no institutions are safe. So far from being an isolated phenomenon the late war is only an example of the disruptive result that we may constantly expect from the progress of science. The future will be no primrose path. It will have its own problems. Some will be the secular problems of the past, giant flowers of evil blossoming at last to their own destruction. Others will be wholly new. Whether in the end man will survive his ascensions of power we cannot tell. But the problem is no new one. It is the old paradox of freedom re-enacted with mankind for actor and the earth for stage.

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„I suppose the process of acceptance will pass through the usual four stages:
(i) this is worthless nonsense;
(ii) this is an interesting, but perverse, point of view;
(iii) this is true, but quite unimportant;
(iv) I always said so.“

— J. B. S. Haldane
Journal of Genetics Vol. 58, page 464 (1963). Haldane may have been putting his own twist on a phrase he had heard elsewhere, since similar statements can be found earlier. On p. 113 of The Art of Scientific Investigation http://www.archive.org/stream/artofscientifici00beve#page/112/mode/2up (1955), William Ian Beardmore Beveridge wrote: <blockquote>It has been said that the reception of an original contribution to knowledge may be divided into three phases: during the first it is ridiculed as not true, impossible or useless; during the second, people say that there may be something in it but it would never be of any practical use; and in the third and final phase, when the discovery has received general recognition, there are usually people who say that it is not original and has been anticipated by others.</blockquote>

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