- Key People:
- Herbert Spencer
- Alfred Russel Wallace
- Related Topics:
- adaptation
- natural selection
- Darwinian fitness
survival of the fittest
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What does 'survival of the fittest' mean in biology?
In biology, "survival of the fittest" describes how organisms best suited to their environment are the most successful in surviving and reproducing. British naturalist Charles Darwin popularized the term in On the Origin of Species, borrowing it from English sociologist Herbert Spencer. Darwin saw evolution not as survival of the fittest, but of the fitter within specific ecosystems, where success can change with altered circumstances.
Darwin's theory includes variation, reproduction, and heritability. Beneficial physical variations are passed on because individuals with those traits tend to survive. The success of a variation is only known after it has been tested by the survival and reproduction of the organisms that possess it.
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How does 'survival of the fittest' relate to natural selection?
The phrase "survival of the fittest," popularized by Charles Darwin in On the Origin of Species, describes organisms best suited to their environment surviving and reproducing. Darwin borrowed the term from Herbert Spencer, who coined it in 1864.
"Survival of the fittest" is often used as a synonym for natural selection which is a natural process where organisms that are well-adjusted to their environment thrive and reproduce, passing on the genetic qualities that are best suited for that environment. Darwin saw evolution not just as survival of the fittest, but as survival of the fitter, recognizing that the "struggle for existence" is relative, not absolute.
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What makes an organism 'fit' in its environment?
In biology, an organism's "fitness" refers to its capacity to survive and reproduce successfully in its environment. This involves the organism's structure, physiology, genetics, locomotion, means of defense, and reproduction.
Natural selection favors hereditary variants that improve survival and reproduction, leading to adaptation to the environment. Favorable variations are preserved and passed on, while less advantageous ones diminish. The measure of the effects of natural selection is quantified by Darwinian fitness, which is the relative probability that a hereditary characteristic will be reproduced. An organism's fitness can change when environmental conditions change.
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Can you give examples of traits that help organisms survive?
"Survival of the fittest" refers to the organisms best suited to thrive in their environment due to advantageous traits. These traits enhance survival and reproductive success.
Examples of traits that help organisms survive:
* Camouflage: Coloration and patterns that allow an organism to blend in with its surroundings, avoiding predators or ambushing prey.
* Thermoregulation: Physiological and behavioral mechanisms that allow organisms to maintain a stable internal temperature, crucial for survival in extreme climates.
* Mutation: Genetic mutations can lead to new traits, such as resistance to pesticides or antibiotics, that enhance survival in changing environments.4 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How do changing environments affect which traits are 'fittest'?
In biology, the environment plays a crucial role in determining which traits are considered the "fittest" for survival. "Survival of the fittest" refers to the natural process where organisms best suited to their environment are most likely to survive and reproduce, also known as natural selection.
When environmental conditions change, the traits that were once advantageous may become less so, and different traits may become more beneficial. This can lead to directional selection, where the distribution of phenotypes in a population shifts systematically in a particular direction due to the changing environment. Examples include insects developing resistance to pesticides and the industrial melanism observed in moths.
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Why is 'survival of the fittest' important for evolution?
The term "survival of the fittest" suggests that the organisms best suited to their environment are the most likely to survive and reproduce. First used by Herbert Spencer, Charles Darwin later popularized the term in the fifth edition of On the Origin of Species. Darwin saw evolution not as survival of the fittest, but survival of the fitter, because the "struggle for existence" is relative.
Darwin's evolution theory includes variation, reproduction, and heritability. Organisms with beneficial physical traits for survival tend to pass them on because they survive and reproduce. "Survival of the fittest" highlights that traits increasing survival and reproduction become more common in a population over time, driving evolutionary change. Natural selection isn't just about strength; it can favor traits like sneakiness or attractiveness.
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survival of the fittest, term made famous in the fifth edition (published in 1869) of On the Origin of Species by British naturalist Charles Darwin, which suggested that organisms best adjusted to their environment are the most successful in surviving and reproducing. Darwin borrowed the term from English sociologist and philosopher Herbert Spencer, who first used it in his 1864 book Principles of Biology. (Spencer came up with the phrase only after reading Darwinâs work.)
(Read T. H. Huxleyâs 1875 Britannica essay on evolution & biology.)
Use in evolutionary theory
Darwin did not consider the process of evolution as the survival of the fittest; he regarded it as survival of the fitter, because the âstruggle for existenceâ (a term he took from English economist and demographer Thomas Malthus) is relative and thus not absolute. Instead, the winners with respect to species within ecosystems could become losers with a change of circumstances. For example, fossil evidence supports the notion that the mammoth (Mammuthus) was more fit during the most recent ice age (which ended roughly 11,700 years ago), but it became less fit as humans hunted it and the worldâs climate warmed; fossil evidence suggests that the mammoth succumbed to extinction a few thousand years later.
(Read Thomas Malthusâs 1824 Britannica essay on population.)
Darwinâs theory of evolution by natural selection entailed three crucial elements: variation, reproduction, and heritability. Variations in the physical features of organisms that tend to benefit an individual (or a species) in the struggle for existence are preserved and passed on (or selected), because the individuals (or species) that have them tend to survive. The success or failure of a given variation is not known when it emerges; it is known only retrospectively, after organisms that possess it either grow and mature and pass it to their own offspring or fail to mature and reproduce.
Importantly, Darwin was influenced by the thinking of English physicist and mathematician Isaac Newton, whose system emphasized experimentation, mathematics, and logic over subjective sense experience. During Darwinâs time, his evolutionary theory was an attempt to construct a similar system for the living world, a frontier not yet crossed in the biological sciences.
Some philosophers and scientists have suggested that the notion of survival of the fittest is an example of circular reasoningâthat is, a tautology (a statement framed in such a way that it cannot be falsified without inconsistency). In tautologies, any true statements that follow are a matter of definition. Indeed, describing those that survive as the fittest is similar to stating that those that survive survive. British philosopher Karl Popper considered âsurvival of the fittestâ self-evident at first; however, he changed his mind after realizing that Darwin posited variation axiomatically; that is, Darwin noted that all individuals did not start with the same set of characters (or traits). Therefore, the forces affecting survival did not weigh on individuals and species equally; there were always variations, some of which would prove favourable and confer fitness over others.
Application to economics
Darwin was also influenced by Scottish philosopher Adam Smith, whose An Inquiry into the Nature and Causes of the Wealth of Nations was published in 1776. In this work, Smith venerated self-interest: âIt is not from the benevolence of the butcher, the brewer, or the baker that we expect our dinner, but from their regard to their own interest.â Such self-interest was based on a philosophical view of the world that posited that only individuals, and not groups, were the important elements. In so doing, Smith was aligning himself with a nominalist worldview (which held that reality is only made up of concrete and individual items). According to Smith, what he termed the âinvisible handââa metaphor in which beneficial social and economic outcomes arose from the accumulated self-interested actions of individualsâwould settle matters between people, bringing a sense of balance to their performance. Smithâs worldview was associated with the doctrine of laissez-faire economics (the policy of minimum governmental interference in the economic affairs of individuals and society), and it is reflected in Darwinâs own account of evolution by natural selection:
It may be said that natural selection is daily and hourly scrutinizing throughout the world, every variation, even the slightest; rejecting that which is bad, preserving and adding up all that is good; silently and insensibly working, whenever and wherever opportunity offers, at the improvement of each organic being in relation to its organic and inorganic conditions of life.
Eugenics
The logic of survival of the fittest and natural selection was thought to be transferable to humanity. Within the context of the ascendancy of Victorian England (1820â1914), a perspective arose that the more intelligent would rule the less intelligent, or those who were less fit. To realize this perspective, Darwinâs cousin, British scientist Francis Galton, who coined the term eugenics (derived from the Greek for âwell-bornâ), established the Eugenics Education Society of London in 1907. Galton, along with many others among the educated classes, hoped to actively discourage the overbreeding of the less fit and so preserve what was best in Victorian society.
As it related to the concept of survival of the fittest, eugenics was divided into positive and negative forms, with positive eugenics actively encouraging good breeding and negative eugenics preventing bad breeding. A pertinent example of negative eugenics appeared in the work of American psychologist Robert Yerkes. During World War I Yerkes analyzed the intelligence of U.S. Army recruits, and he concluded that heritable traits accounted for differences in intelligence between races, despite his use of culturally biased intelligence tests. U.S. Pres. Calvin Coolidge, who was influenced by Yerkesâs findings, signed the 1924 Immigration Act, a law that prevented people from immigrating to the United States by virtue of their nationality or race. In 1907 Indiana became the first U.S. state to pass laws that allowed for compulsory sterilization of those who had been classified as âunfit.â More than 29 other states would follow, passing their own compulsory sterilization laws; however, the eugenics movement in the U.S. declined in popularity after the 1920s.
The eugenics movement burgeoned in Europe during the 1920s and 1930s. German politician Adolf Hitler wrote, in Mein Kampf (1925), that âpositive steps should be taken to encourage the flourishing of the fitter, because the system itself often worked against them.â In this passage Hitler appears to twist the tenets of Darwinism to support his fascist worldview. Eugenics lost much of its appeal in Europe and elsewhere after World War II, due to its association with Nazi Germany.

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