page_title: Natural selection
section_title: Pre-Darwinian theories
hierarchical_section_title: Natural selection / Historical development / Pre-Darwinian theories
caption_attribution_description: English: Bust of Aristotle. Marble, Roman copy after a Greek bronze original by Lysippos from 330 BC; the alabaster mantle is a modern addition. বাংলা: এরিস্টটলের আবক্ষ মূর্তি, লিসিপস কর্তৃক ৩৩০ খ্রিস্টপূর্বাব্দে নির্মিত গ্রিক ব্রোঞ্জ ভাষ্কের্যর মার্বেল সংস্করণ। Español: Busto de Aristóteles, que se halla en el Palacio Altemps, Roma. en mármol, copia romana de un original griego de Lisipo ( ca. 330 aC ); el manto de alabastro es una adición moderna. De la colección Ludovisi. Français&#160;: Buste d'Aristote. Marbre, copie romaine d'un original grec en bronze de Lysippse (vers 330 av. J.-C.). Ancienne collection Ludovisi.Deutsch: Büste von Aristoteles. Marmor. Römische Kopie nach dem griechischen Bronze-Original von Lysippos, um 330 vor Chr. Der Alabaster-Mantel ist eine Ergänzung in der Moderne. Italiano: Ritratto di Aristotele, conservato a Palazzo Altaemps, Roma. Marmo, copia romana di un originale greco di Lisippo (330 a.C. ca.); il mantello in alabastro è un'aggiunta moderna. Dalla collezione Ludovisi. Português: Busto de Aristóteles. Mámore, cópia romana de um original grego em bronze por Lísipo cerca 330 AEC; o manto em alabastro é uma adição moderna.
context_page_description: Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charles Darwin popularised the term "natural selection", contrasting it with artificial selection, which in his view is intentional, whereas natural selection is not.
  Variation exists within all populations of organisms. This occurs partly because random mutations arise in the genome of an individual organism, and their offspring can inherit such mutations. Throughout the lives of the individuals, their genomes interact with their environments to cause variations in traits. The environment of a genome includes the molecular biology in the cell, other cells, other individuals, populations, species, as well as the abiotic environment. Because individuals with certain variants of the trait tend to survive and reproduce more than individuals with other less successful variants, the population evolves. Other factors affecting reproductive success include sexual selection and fecundity selection.
context_section_description: Several philosophers of the classical era, including Empedocles and his intellectual successor, the Roman poet Lucretius, expressed the idea that nature produces a huge variety of creatures, randomly, and that only those creatures that manage to provide for themselves and reproduce successfully persist. Empedocles' idea that organisms arose entirely by the incidental workings of causes such as heat and cold was criticised by Aristotle in Book II of Physics. He posited natural teleology in its place, and believed that form was achieved for a purpose, citing the regularity of heredity in species as proof. Nevertheless, he accepted in his biology that new types of animals, monstrosities (τερας), can occur in very rare instances (Generation of Animals, Book IV). As quoted in Darwin's 1872 edition of The Origin of Species, Aristotle considered whether different forms (e.g., of teeth) might have appeared accidentally, but only the useful forms survived:
  So what hinders the different parts [of the body] from having this merely accidental relation in nature? as the teeth, for example, grow by necessity, the front ones sharp, adapted for dividing, and the grinders flat, and serviceable for masticating the food; since they were not made for the sake of this, but it was the result of accident. And in like manner as to the other parts in which there appears to exist an adaptation to an end. Wheresoever, therefore, all things together (that is all the parts of one whole) happened like as if they were made for the sake of something, these were preserved, having been appropriately constituted by an internal spontaneity, and whatsoever things were not thus constituted, perished, and still perish.
  — Aristotle, Physics, Book II, Chapter 8
  But Aristotle rejected this possibility in the next paragraph, making clear that he is talking about  the development of animals as embryos with the phrase "either invariably or normally come about", not the origin of species:
  ... Yet it is impossible that this should be the true view. For teeth and all other natural things either invariably or normally come about in a given way; but of not one of the results of chance or spontaneity is this true. We do not ascribe to chance or mere coincidence the frequency of rain in winter, but frequent rain in summer we do; nor heat in the dog-days, but only if we have it in winter. If then, it is agreed that things are either the result of coincidence or for an end, and these cannot be the result of coincidence or spontaneity, it follows that they must be for an end; and that such things are all due to nature even the champions of the theory which is before us would agree. Therefore action for an end is present in things which come to be and are by nature.
  — Aristotle, Physics, Book II, Chapter 8
  The struggle for existence was later described by the Islamic writer Al-Jahiz in the 9th century.
  The classical arguments were reintroduced in the 18th century by Pierre Louis Maupertuis and others, including Darwin's grandfather, Erasmus Darwin.
  Until the early 19th century, the prevailing view in Western societies was that differences between individuals of a species were uninteresting departures from their Platonic ideals (or typus) of created kinds. However, the theory of uniformitarianism in geology promoted the idea that simple, weak forces could act continuously over long periods of time to produce radical changes in the Earth's landscape. The success of this theory raised awareness of the vast scale of geological time and made plausible the idea that tiny, virtually imperceptible changes in successive generations could produce consequences on the scale of differences between species.
  The early 19th-century zoologist Jean-Baptiste Lamarck suggested the inheritance of acquired characteristics as a mechanism for evolutionary change; adaptive traits acquired by an organism during its lifetime could be inherited by that organism's progeny, eventually causing transmutation of species. This theory, Lamarckism, was an influence on the Soviet biologist Trofim Lysenko's antag
caption: Aristotle considered whether different forms could have appeared, only the useful ones surviving.
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