"Survival of the fittest" is a phrase originating in evolutionary theory, as an alternative description of Natural selection. The phrase is today commonly used in contexts that are incompatible with the original meaning as intended by its first two proponents: British polymath philosopher Herbert Spencer (who coined the term) and Charles Darwin.
Herbert Spencer first used the phrase – after reading Charles Darwin's On the Origin of Species – in his Principles of Biology (1864), in which he drew parallels between his own economic theories and Darwin's biological ones, writing, "This survival of the fittest, which I have here sought to express in mechanical terms, is that which Mr. Darwin has called 'natural selection', or the preservation of favoured races in the struggle for life."[1]
Darwin first used Spencer's new phrase "survival of the fittest" as a synonym for natural selection in the fifth edition of On the Origin of Species, published in 1869.[2][3] Darwin meant it as a metaphor for "better adapted for immediate, local environment", not the common inference of "in the best physical shape".[4] Hence, it is not a scientific description.[5]
The phrase "survival of the fittest" is not generally used by modern biologists as the term does not accurately convey the meaning of natural selection, the term biologists use and prefer. Natural selection refers to differential reproduction as a function of traits that have a genetic basis. "Survival of the fittest" is inaccurate for two important reasons. First, survival is merely a normal prerequisite to reproduction. Second, fitness has specialized meaning in biology different from how the word is used in popular culture. In population genetics, fitness refers to differential reproduction. "Fitness" does not refer to whether an individual is "physically fit" – bigger, faster or stronger – or "better" in any subjective sense. It refers to a difference in reproductive rate from one generation to the next.[6]
An interpretation of the phrase "survival of the fittest" to mean "only the fittest organisms will prevail" (a view sometimes derided as "Social Darwinism") is not consistent with the actual theory of evolution. Any individual organism which succeeds in reproducing itself is "fit" and will contribute to survival of its species, not just the "physically fittest" ones, though some of the population will be better adapted to the circumstances than others. A more accurate characterization of evolution would be "survival of the fit enough".[7]
"Survival of the fit enough" is also emphasized by the fact that while direct competition has been observed between individuals, populations and species, there is little evidence that competition has been the driving force in the evolution of large groups. For example, between amphibians, reptiles and mammals; rather these animals have evolved by expanding into empty ecological niches.[8]
Moreover, to misunderstand or misapply the phrase to simply mean "survival of those who are better equipped for surviving" is rhetorical tautology. What Darwin meant was "better adapted for immediate, local environment" by differential preservation of organisms that are better adapted to live in changing environments. The concept is not tautological as it contains an independent criterion of fitness.[4]
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Herbert Spencer first used the phrase — after reading Charles Darwin's On the Origin of Species — in his Principles of Biology of 1864[9] in which he drew parallels between his economic theories and Darwin's biological, evolutionary ones, writing, “This survival of the fittest, which I have here sought to express in mechanical terms, is that which Mr. Darwin has called 'natural selection', or the preservation of favoured races in the struggle for life."[1]
In the first four editions of On the Origin of Species, Darwin used the phrase "natural selection".[10] Darwin wrote on page 6 of The Variation of Animals and Plants under Domestication published in 1868, "This preservation, during the battle for life, of varieties which possess any advantage in structure, constitution, or instinct, I have called Natural Selection; and Mr. Herbert Spencer has well expressed the same idea by the Survival of the Fittest. The term "natural selection" is in some respects a bad one, as it seems to imply conscious choice; but this will be disregarded after a little familiarity". Darwin agreed with Alfred Russel Wallace that this new phrase — "survival of the fittest" — avoided the troublesome anthropomorphism of "selecting", though it "lost the analogy between nature's selection and the fanciers'". In Chapter 4 of the 5th edition of The Origin published in 1869,[2] Darwin implies again the synonym: "Natural Selection, or the Survival of the Fittest".[3] By the word "fittest" Darwin meant "better adapted for immediate, local environment", not the common modern meaning of "in the best physical shape".[4] In the introduction he gave full credit to Spencer, writing "I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection, in order to mark its relation to man's power of selection. But the expression often used by Mr. Herbert Spencer of the Survival of the Fittest is more accurate, and is sometimes equally convenient."[11]
In The Man Versus The State, Spencer used the phrase in a postscript to justify a plausible explanation for why his theories would not be adopted by "societies of militant type". He uses the term in the context of societies at war, and the form of his reference suggests that he is applying a general principle.[12]
"Thus by survival of the fittest, the militant type of society becomes characterized by profound confidence in the governing power, joined with a loyalty causing submission to it in all matters whatever".[13]
Herbert Spencer is credited with starting the concept of Social Darwinism. The phrase "survival of the fittest" has become widely used in popular literature as a catchphrase for any topic related or analogous to evolution and natural selection. It has thus been applied to principles of unrestrained competition, and it has been used extensively by both proponents and opponents of Social Darwinism. Its shortcomings as a description of Darwinian evolution have also become more apparent (see below).
Evolutionary biologists criticize how the term is used by non-scientists and the connotations that have grown around the term in popular culture. The phrase also does not help in conveying the complex nature of natural selection, so modern biologists prefer and almost exclusively use the term natural selection. Indeed, in modern biology, the term fitness mostly refers to reproductive success, and is not explicit about the specific ways in which organisms can be "fit" as in "having phenotypic characteristics which enhance survival and reproduction" (which was the meaning that Spencer had in mind).
In 2010 Sahney et al. argued that there is little evidence that intrinsic, biological factors such as competition have been the driving force in the evolution of large groups. Instead, they cited extrinsic, abiotic factors such as expansion as the driving factor on a large evolutionary scale. The rise of dominant groups such as amphibians, reptiles, mammals and birds occurred by opportunistic expansion into empty ecological niches and the extinction of groups happened due to large shifts in the abiotic environment.[8]
"Survival of the fittest" is sometimes claimed to be a tautology.[14] The reasoning is that if one takes the term "fit" to mean "endowed with phenotypic characteristics which improve chances of survival and reproduction" (which is roughly how Spencer understood it), then "survival of the fittest" can simply be rewritten as "survival of those who are better equipped for surviving". Furthermore, the expression does become a tautology if one uses the most widely accepted definition of "fitness" in modern biology, namely reproductive success itself (rather than any set of characters conducive to this reproductive success). This reasoning is sometimes used to claim that Darwin's entire theory of evolution by natural selection is fundamentally tautological, and therefore devoid of any explanatory power.
However, the expression "survival of the fittest" (taken on its own and out of context) gives a very incomplete account of the mechanism of natural selection. The reason is that it does not mention a key requirement for natural selection, namely the requirement of heritability. It is true that the phrase "survival of the fittest", in and by itself, is a tautology if fitness is defined by survival and reproduction. Natural selection is the portion of variation in reproductive success that is caused by heritable characters (see the article on natural selection).
If certain heritable characters increase or decrease the chances of survival and reproduction of their bearers, then it follows mechanically (by definition of "heritable") that those characters that improve survival and reproduction will increase in frequency over generations. This is precisely what is called "evolution by natural selection." On the other hand, if the characters which lead to differential reproductive success are not heritable, then no meaningful evolution will occur, "survival of the fittest" or not: if improvement in reproductive success is caused by traits that are not heritable, then there is no reason why these traits should increase in frequency over generations. In other words, natural selection does not simply state that "survivors survive" or "reproducers reproduce"; rather, it states that "survivors survive, reproduce and therefore propagate any heritable characters which have affected their survival and reproductive success". This statement is not tautological: it hinges on the testable hypothesis that such fitness-impacting heritable variations actually exist (a hypothesis that has been amply confirmed.)
Skeptic Society founder and Skeptic magazine publisher Dr. Michael Shermer addresses this argument in his 1997 book, Why People Believe Weird Things, in which he points out that although tautologies are sometimes the beginning of science, they are never the end, and that scientific principles like natural selection are testable and falsifiable by virtue of their predictive power. Shermer points out, as an example, that population genetics accurately demonstrate when natural selection will and will not effect change on a population. Shermer hypothesizes that if hominid fossils were found in the same geological strata as trilobites, it would be evidence against natural selection.[15]
Critics of evolution have argued that "survival of the fittest" provides a justification for behaviour that undermines moral standards by letting the strong set standards of justice to the detriment of the weak.[16] However, any use of evolutionary descriptions to set moral standards would be a naturalistic fallacy (or more specifically the is-ought problem), as prescriptive moral statements cannot be derived from purely descriptive premises. Describing how things are does not imply that things ought to be that way. It is also suggested that "survival of the fittest" implies treating the weak badly, even though in some cases of good social behaviour — cooperating with others and treating them well — might improve evolutionary fitness.[17][18] This however does not resolve the is-ought problem.
It has also been claimed that "the survival of the fittest" theory in biology was interpreted by late 19th century capitalists as "an ethical precept that sanctioned cut-throat economic competition" and led to "social Darwinism" which at times were used to justify laissez-faire economics, war and racism. However these ideas predate and commonly contradict Darwin's ideas, and indeed their proponents rarely invoked Darwin in support, while commonly claiming justification from religion and Horatio Alger mythology. The term "social Darwinism" referring to capitalist ideologies was introduced as a term of abuse by Richard Hofstadter's Social Darwinism in American Thought published in 1944.[18][19]
Russian anarchist Peter Kropotkin viewed the concept of "survival of the fittest" as supporting co-operation rather than competition. In his book Mutual Aid: A Factor of Evolution he set out his analysis leading to the conclusion that the fittest was not necessarily the best at competing individually, but often the community made up of those best at working together. He concluded that
In the animal world we have seen that the vast majority of species live in societies, and that they find in association the best arms for the struggle for life: understood, of course, in its wide Darwinian sense — not as a struggle for the sheer means of existence, but as a struggle against all natural conditions unfavourable to the species. The animal species, in which individual struggle has been reduced to its narrowest limits, and the practice of mutual aid has attained the greatest development, are invariably the most numerous, the most prosperous, and the most open to further progress.
Applying this concept to human society, Kropotkin presented mutual aid as one of the dominant factors of evolution, the other being self assertion, and concluded that
In the practice of mutual aid, which we can retrace to the earliest beginnings of evolution, we thus find the positive and undoubted origin of our ethical conceptions; and we can affirm that in the ethical progress of man, mutual support not mutual struggle – has had the leading part. In its wide extension, even at the present time, we also see the best guarantee of a still loftier evolution of our race.