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The Genetical Theory of Natural Selection
This is the definitive edition of R.A. Fisher's classic work--probably the best known book in evolutionary biology after Darwin's Origin of Species. The book was the first attempt to assess and explain Darwin's evolutionary theories in terms of genetic evolution. Based on the original 1930 edition, the book incorporates the many changes Fisher made for the second edition as well as unpublished material taken from Fisher's own copy.
310 pages, Paperback
First published January 1, 1930
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Displaying 1 - 6 of 6 reviews
February 27, 2016
This is widely considered to be one of the most important books on evolutionary biology ever written. Those interested in reading it would do well to start by looking at modern professional perspectives provided by Jim Crow here, AWF Edwards here, and Alan Grafen here.
Yet be warned - Fisher's style is difficult – whereas a modern writer would spend several pages explaining an idea giving context and possibly looking at that idea from several different angles, and considering its wider implications, Fisher condenses the same material into one terse sentence; sometimes less. The result is an arrogant challenge to the reader – “I understand this, now you decipher it”.
Fortunately commentary by more modern biologists can be used to develop a background understanding which can be used as a key to unlock the hidden meaning. But it does require work. The final 5 chapters on eugenics are literarily more readable but were highly speculative when written and are likely to offend modern sensibilities.
This then is a book of extremes and difficult to give a rating. The historical importance and prescient biological content demand a five star rating; the writing style and nonsensical/speculative eugenic content require one.
Yet be warned - Fisher's style is difficult – whereas a modern writer would spend several pages explaining an idea giving context and possibly looking at that idea from several different angles, and considering its wider implications, Fisher condenses the same material into one terse sentence; sometimes less. The result is an arrogant challenge to the reader – “I understand this, now you decipher it”.
Fortunately commentary by more modern biologists can be used to develop a background understanding which can be used as a key to unlock the hidden meaning. But it does require work. The final 5 chapters on eugenics are literarily more readable but were highly speculative when written and are likely to offend modern sensibilities.
This then is a book of extremes and difficult to give a rating. The historical importance and prescient biological content demand a five star rating; the writing style and nonsensical/speculative eugenic content require one.
April 15, 2016
The first half of this book gives the mathematics behind the integration of Mendelian Genetics and Darwinian selection theory. Fisher shows that neither make sense without the other, contrary to the opinions of the times which held that Mendel largely superseded Darwin. This is arguably the second most important work on evolutionary biology ever published.
The second half of the book explains and predicts the contemporary Idiocracy. Skip the math, if you must, read this section and have your mind blown.
The second half of the book explains and predicts the contemporary Idiocracy. Skip the math, if you must, read this section and have your mind blown.
April 13, 2024
So Darwin's evolutionary theory had an unsolved problem at the beginning - the laws of inheritance were unknown to Darwin. This led some authors to speculate on the so-called blending theory - in which natural selection couldn't force organisms to evolve. As there wouldn't be an inherited trait but only diluted halved material from parents. Darwin had some arguments that this wouldn't be the case - well male and female horses breed, and they don't seem to have a child with blended sex... Therefore some mechanism that held some traits constant should have been in play, Darwin thought. But it was Mendel that gave way to modern genetics and what Fisher calls particulate theory which is in line with Darwinian evolutionary theory. There will be dominant (p) a recessive gene (q) in the population with a certain frequency in the population (genotype) - p2+2pq+q2= 1. The book then goes about how to express population genetics with evolution by mathematical formulation. And some hundred or so pages are dedicated to eugenics - although as such it slips me why such an intelligent person should believe that morals are inherited. I would skip this part as it is irrelevant, but read it from curiosity alone. It's antiquated at best - dangerous to believe at worst. With all honesty, I read this book, for the most part, to read about Fisherian runaway sexual selection - as such, below are some excerpts for my later usage:
Concerning sexual reproduction and sexual selection:
The contrast between sexual and asexual reproduction
It is tempting to believe that asexual reproduction was the primitive condition of living matter and that the sexual reproduction of the predominant types of organisms is a development of some special value to the organisms that employ it. The development of separate sexes in motile animals and of the many devices to ensure cross-pollination in plants, though not the origin of sexual reproduction itself, seems to be ascribable to the small constant individual advantages due to the favoring of the heterozygote; at least if we include in this phrase the constant tendency of the heterozygote to resemble the more favorable homozygous form.
If the total rate of mutations is so small that the usual condition of the group is one of genetic uniformity, any advantageous mutation may be expected to prevail, provided it survives the chances of accidental death during the initial period in which it is represented by only one or few individuals. But it is not difficult to see that the rate of progress, supposing that the optimum mutability was established, would still be very inferior to that of a sexual organism placed in the same circumstances.
A) The nature of species
The effective identity of the remote ancestry of all existing members of a single sexual species may be seen in a way that, in particular cases should be capable of some quantitative refinement. Of the heritable variance in any character in each generation, a portion is due to the hereditary differences in their parents, while the remainder, including nearly all differences between whole brothers and sisters, is due to genetic segregation. These portions are not very unequal; the correlations observed in human statistics show that segregation must account for a little more than two-fifths, and the hereditary differences of the parents for nearly three-fifths of the whole. As we look farther and farther back, the proportion of the existing variance ascribable to differences of ancestry becomes rapidly smaller and smaller.
B) Fission of species
In many cases without doubt the establishment of complete or almost complete geographical
isolation has at once settled the line of fission; the two separated moieties thereafter evolve as separate species, in almost complete independence, in somewhat different habitats, until the morphological differences between them entitle them to specific rank.
We may consider the case of a species subjected to different conditions of survival and reproduction at opposite ends of its geographical range. A condition of genetic equilibrium is therefore only established if the increase in frequency in the favorable region and the decrease in frequency in the unfavorable region, not only balance each other quantitatively but are each equal to the rate at which genes diffuse by migration and sexual union, from the one region to the other.
So long as a sufficient gradient can be maintained, accompanied by an active diffusion of germinal material, so long the local varieties, although distinct differences between them may be detected, will be connected by all grades of intermediate types of population.
C) Sexual preference
The general conditions upon which discrimination, when possible, can usefully be exercised seem to be:
(i) that the acceptance of one mate precludes the effective acceptance of alternative mates,
(ii) that the rejection of an offer will be followed by other offers, either certainly, or with such high probability, that the risk of their non-occurrence shall be smaller than the probable advantage to be gained by the choice of a mate.
For example, individuals in each region most readily attracted to or excited by mates of the type (special tint) they favored, in contrast to possible mates of the opposite type, will, be better represented in future generations, and both the discrimination and the preference will thereby be enhanced. It appears certainly possible that an evolution of sexual preference due to this cause would establish an effective isolation between two differentiated parts of a species, even when geographical and other factors were least favorable to such separation.
D) Sexual selection
It involves two rather distinct principles. In one group of cases, common among mammals, the males, especially when polygamous, do battle for the possession of the females. For the second class of cases, extraordinary developments in phenotype are due to the cumulative action of sexual preference exerted by the females at the time of mating.
Darwin supposes in effect that there is a positive correlation in the females between the earliness with which they are ready to breed, and the number of offspring they rear, variations in both these variates being associated, as Darwin suggests, with a higher nutritional condition. Whether this is so in fact it is difficult to say.
E) Sex limitation of modifications
The difficulty lay in how far selection acting on only one sex ought to be expected to affect the characters of both sexes, and whether a mutation originally affecting the development of both sexes could be confined to one sex only, by counterselection on the other sex.
Sex ratio: If we consider the aggregate of an entire generation of such offspring it is clear that the total reproductive value of the males in this group is exactly equal to the total value of all the females because each sex must supply half the ancestry of all future generations of the species. From this, it follows that the sex ratio will so adjust itself, under the influence of Natural Selection, that the total parental expenditure incurred in respect of children of each sex, shall be equal (aka 50:50 sex ratio).
Runaway selection: In species so situated that the reproductive success of one sex depends greatly upon winning the favor of the other, as appears evidently to be the case with many polygamous birds, sexual selection will itself act by increasing the intensity of the preference to which it is due, with the consequence that both the feature preferred and the intensity of preference will be augmented together with ever-increasing velocity, causing a great and rapid evolution of certain conspicuous characteristics, until it can be arrested by the direct or indirect effects of Natural Selection.
Concerning sexual reproduction and sexual selection:
The contrast between sexual and asexual reproduction
It is tempting to believe that asexual reproduction was the primitive condition of living matter and that the sexual reproduction of the predominant types of organisms is a development of some special value to the organisms that employ it. The development of separate sexes in motile animals and of the many devices to ensure cross-pollination in plants, though not the origin of sexual reproduction itself, seems to be ascribable to the small constant individual advantages due to the favoring of the heterozygote; at least if we include in this phrase the constant tendency of the heterozygote to resemble the more favorable homozygous form.
If the total rate of mutations is so small that the usual condition of the group is one of genetic uniformity, any advantageous mutation may be expected to prevail, provided it survives the chances of accidental death during the initial period in which it is represented by only one or few individuals. But it is not difficult to see that the rate of progress, supposing that the optimum mutability was established, would still be very inferior to that of a sexual organism placed in the same circumstances.
A) The nature of species
The effective identity of the remote ancestry of all existing members of a single sexual species may be seen in a way that, in particular cases should be capable of some quantitative refinement. Of the heritable variance in any character in each generation, a portion is due to the hereditary differences in their parents, while the remainder, including nearly all differences between whole brothers and sisters, is due to genetic segregation. These portions are not very unequal; the correlations observed in human statistics show that segregation must account for a little more than two-fifths, and the hereditary differences of the parents for nearly three-fifths of the whole. As we look farther and farther back, the proportion of the existing variance ascribable to differences of ancestry becomes rapidly smaller and smaller.
B) Fission of species
In many cases without doubt the establishment of complete or almost complete geographical
isolation has at once settled the line of fission; the two separated moieties thereafter evolve as separate species, in almost complete independence, in somewhat different habitats, until the morphological differences between them entitle them to specific rank.
We may consider the case of a species subjected to different conditions of survival and reproduction at opposite ends of its geographical range. A condition of genetic equilibrium is therefore only established if the increase in frequency in the favorable region and the decrease in frequency in the unfavorable region, not only balance each other quantitatively but are each equal to the rate at which genes diffuse by migration and sexual union, from the one region to the other.
So long as a sufficient gradient can be maintained, accompanied by an active diffusion of germinal material, so long the local varieties, although distinct differences between them may be detected, will be connected by all grades of intermediate types of population.
C) Sexual preference
The general conditions upon which discrimination, when possible, can usefully be exercised seem to be:
(i) that the acceptance of one mate precludes the effective acceptance of alternative mates,
(ii) that the rejection of an offer will be followed by other offers, either certainly, or with such high probability, that the risk of their non-occurrence shall be smaller than the probable advantage to be gained by the choice of a mate.
For example, individuals in each region most readily attracted to or excited by mates of the type (special tint) they favored, in contrast to possible mates of the opposite type, will, be better represented in future generations, and both the discrimination and the preference will thereby be enhanced. It appears certainly possible that an evolution of sexual preference due to this cause would establish an effective isolation between two differentiated parts of a species, even when geographical and other factors were least favorable to such separation.
D) Sexual selection
It involves two rather distinct principles. In one group of cases, common among mammals, the males, especially when polygamous, do battle for the possession of the females. For the second class of cases, extraordinary developments in phenotype are due to the cumulative action of sexual preference exerted by the females at the time of mating.
Darwin supposes in effect that there is a positive correlation in the females between the earliness with which they are ready to breed, and the number of offspring they rear, variations in both these variates being associated, as Darwin suggests, with a higher nutritional condition. Whether this is so in fact it is difficult to say.
E) Sex limitation of modifications
The difficulty lay in how far selection acting on only one sex ought to be expected to affect the characters of both sexes, and whether a mutation originally affecting the development of both sexes could be confined to one sex only, by counterselection on the other sex.
Sex ratio: If we consider the aggregate of an entire generation of such offspring it is clear that the total reproductive value of the males in this group is exactly equal to the total value of all the females because each sex must supply half the ancestry of all future generations of the species. From this, it follows that the sex ratio will so adjust itself, under the influence of Natural Selection, that the total parental expenditure incurred in respect of children of each sex, shall be equal (aka 50:50 sex ratio).
Runaway selection: In species so situated that the reproductive success of one sex depends greatly upon winning the favor of the other, as appears evidently to be the case with many polygamous birds, sexual selection will itself act by increasing the intensity of the preference to which it is due, with the consequence that both the feature preferred and the intensity of preference will be augmented together with ever-increasing velocity, causing a great and rapid evolution of certain conspicuous characteristics, until it can be arrested by the direct or indirect effects of Natural Selection.
September 10, 2017
a fascinating and thought-provoking book though I had trouble following some of the math midway through-- I'm woefully out of date with differentiation and integration, so those parts were a slog.
the more evolutionary psychology focused sections are less objectionable to modern-day sensibilities than one might expect, though the eugenics focused sections, to anyone unfamiliar with the new renaissance in this type of work, might come across as alarmist. The 10000 year explosion by Cochran and Harpending definitely lean heavily on this book, as they acknowledge, but it still amazes me to see how much unexplored but probably fruitful speculation this book contains. more than enough for a couple of grad students to start careers from, honestly...
the more evolutionary psychology focused sections are less objectionable to modern-day sensibilities than one might expect, though the eugenics focused sections, to anyone unfamiliar with the new renaissance in this type of work, might come across as alarmist. The 10000 year explosion by Cochran and Harpending definitely lean heavily on this book, as they acknowledge, but it still amazes me to see how much unexplored but probably fruitful speculation this book contains. more than enough for a couple of grad students to start careers from, honestly...
August 3, 2016
The book that put together quantitative and mendelians
Displaying 1 - 6 of 6 reviews