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Édouard Manet

Édouard Manet (, ; ; 23 January 1832 – 30 April 1883) was a French modernist painter. He was one of the first 19th-century artists to paint modern life, as well as a pivotal figure in the transition from Realism to Impressionism.

Born into an upper-class household with strong political connections, Manet rejected the naval career originally envisioned for him; he became engrossed in the world of painting. His early masterworks, The Luncheon on the Grass (Le déjeuner sur l'herbe) or Olympia, "premiering" in 1863 and '65, respectively, caused great controversy with both critics and the Academy of Fine Arts, but soon were praised by progressive artists as the breakthrough acts to the new style, Impressionism. Today too, these works, along with others, are considered watershed paintings that mark the start of modern art. The last 20 years of Manet's life saw him form bonds with other great artists of the time; he developed his own simple and direct style that would be heralded as innovative and serve as a major influence for future painters.

Early life
Édouard Manet was born in Paris on 23 January 1832, in the ancestral hôtel particulier (mansion) on the Rue des Petits Augustins (now Rue Bonaparte) to an affluent and well-connected family. His mother, Eugénie-Desirée Fournier, was the daughter of a diplomat and goddaughter of the Swedish crown prince Charles Bernadotte, from whom the Swedish monarchs are descended. His father, Auguste Manet, was a French judge who expected Édouard to pursue a career in law. His uncle, Edmond Fournier, encouraged him to pursue painting and took young Manet to the Louvre. In 1844, he enrolled at secondary school, the Collège Rollin, where he boarded until 1848. He showed little academic talent and was generally unhappy at the school. In 1845, at the advice of his uncle, Manet enrolled in a special course of drawing where he met Antonin Proust, future Minister of Fine Arts and subsequent lifelong friend.

At his father's suggestion, in 1848 he sailed on a training vessel to Rio de Janeiro. After he twice failed the examination to join the Navy, his father relented to his wishes to pursue an art education. From 1850 to 1856, Manet studied under the academic painter Thomas Couture. Couture encouraged his students to paint contemporary life, though he would eventually be horrified by Manet's choice of lower-class and "degenerate" subjects such as The Absinthe Drinker. In his spare time, Manet copied Old Masters such as Diego Velázquez and Titian in the Louvre.

From 1853 to 1856, Manet made brief visits to Germany, Italy, and the Netherlands, during which time he was influenced by the Dutch painter Frans Hals and the Spanish artists Velázquez and Francisco José de Goya.

Career
In 1856, Manet opened a studio. His style in this period was characterized by loose brush strokes, simplification of details, and the suppression of transitional tones. Adopting the current style of realism initiated by Gustave Courbet, he painted The Absinthe Drinker (1858–59) and other contemporary subjects such as beggars, singers, Romani, people in cafés, and bullfights. After his early career, he rarely painted religious, mythological, or historical subjects; religious paintings from 1864 include his Jesus Mocked by the Soldiers and The Dead Christ with Angels.

Manet had two canvases accepted at the Salon in 1861. A portrait of his mother and father (Portrait of Monsieur and Madame Manet), the latter of whom at the time was paralysed by a stroke or advanced syphilis, was ill-received by critics. The other, The Spanish Singer, was admired by Théophile Gautier, and placed in a more conspicuous location as a result of its popularity with Salon-goers. Manet's work, which appeared "slightly slapdash" when compared with the meticulous style of so many other Salon paintings, intrigued some young artists and brought new business to his studio. According to one contemporary source, The Spanish Singer, painted in a "strange new fashion[,] caused many painters' eyes to open and their jaws to drop."

Music in the Tuileries
In 1862, Manet exhibited Music in the Tuileries (probably painted in 1860), one of his first masterpieces. With its portrayal of a crowd of subjects at the Jardin des Tuileries, the painting shows the outdoor leisure of contemporary Paris, which would be a lifelong subject of Manet's. Among the figures in the gardens are the poet Charles Baudelaire, the musician Jacques Offenbach, and others of Manet's family and friends, including a self-portrait of the artist.

Music in the Tuileries received substantial critical and public attention, most of it negative. In the words of one Manet biographer, "it is difficult for us to imagine the kind of fury Music in the Tuileries provoked when it was exhibited". By portraying Manet's social circle instead of classical heroes, historical icons, or gods, the painting could be interpreted as challenging the value of those subjects or as an attempt to elevate his contemporaries to the same level. The public, accustomed to the finely detailed brushwork of historical painters such as Ernest Meissonier, thought Manet's thick brushstrokes looked crude and unfinished. Angered by the subject matter and technique, several visitors even threatened to destroy the painting. One of Manet's idols, Eugène Delacroix, was of the painting's few defenders. Despite the largely negative reaction, the controversy made Manet a well-known name in Paris.

Luncheon on the Grass (Le Déjeuner sur l'herbe)
Another major early work is The Luncheon on the Grass (Le Déjeuner sur l'herbe), originally Le Bain. The Paris Salon rejected it for exhibition in 1863, but Manet agreed to exhibit it at the Salon des Refusés (Salon of the Rejected). This parallel salon was initiated by Emperor Napoleon III as a solution to the public outcry after the official salon's Selection Committee only accepted 2217 paintings out of more than 5000 submissions, and allowed rejected artists to still display their paintings if they chose.

The painting's juxtaposition of fully dressed men and a nude woman was controversial, as was its abbreviated, sketch-like handling, an innovation that distinguished Manet from Courbet. One critic stated that the brushwork appeared to have been done with a "floor mop". However, others such as his friend Antonin Proust celebrated the painting, and novelist Émile Zola was so affected by the experience of viewing it that he later based the title painting in his novel L'Œuvre ("The Work of Art") on Le Déjeuner sur l'herbe.

At the same time, Manet's composition reveals his study of the old masters, as the disposition of the main figures is derived from Marcantonio Raimondi's engraving of the Judgement of Paris (c. 1515) based on a drawing by Raphael. Two additional works cited by scholars as important precedents for Le Déjeuner sur l'herbe are Pastoral Concert (c. 1510) and The Tempest, both of which are attributed variously to Italian Renaissance masters Giorgione or Titian.

Le Déjeuner and James McNeill Whistler's Symphony in White, No. 1: The White Girl were the two most discussed works of the Salon des Refusés, which itself would become one of the most famous art exhibitions of all time. Following the Salon, Manet became yet more notorious and widely discussed. However, Le Déjeuner sur l'herbe and Manet's other paintings still failed to sell, and Manet continued living off of his inheritance from his recently deceased father.

Olympia
As he had in Luncheon on the Grass, Manet again paraphrased a respected work by a Renaissance artist in the painting Olympia (1863), a nude portrayed in a style reminiscent of early studio photographs, but whose pose was based on Titian's Venus of Urbino (1538). The painting is also reminiscent of Francisco Goya's painting The Nude Maja (1800).

Manet embarked on the canvas after being challenged to give the Salon a nude painting to display. His uniquely frank depiction of a self-assured prostitute was accepted by the Paris Salon in 1865, where it created a scandal. According to Antonin Proust, "only the precautions taken by the administration prevented the painting being punctured and torn" by offended viewers. The painting was controversial partly because the nude is wearing some small items of clothing such as an orchid in her hair, a bracelet, a ribbon around her neck, and mule slippers, all of which accentuated her nakedness, sexuality, and comfortable courtesan lifestyle. The orchid, upswept hair, black cat, and bouquet of flowers were all recognized symbols of sexuality at the time. This modern Venus' body is thin, counter to prevailing standards; the painting's lack of idealism rankled viewers. The painting's flatness, inspired by Japanese wood block art, serves to make the nude more human and less voluptuous. A fully dressed black servant is featured, exploiting the then-current theory that black people were hyper-sexed. That she is wearing the clothing of a servant to a courtesan here furthers the sexual tension of the piece.

Olympia's body as well as her gaze is unabashedly confrontational. She defiantly looks out as her servant offers flowers from one of her male suitors. Although her hand rests on her leg, hiding her pubic area, the reference to traditional female virtue is ironic; a notion of modesty is notoriously absent in this work. A contemporary critic denounced Olympia's "shamelessly flexed" left hand, which seemed to him a mockery of the relaxed, shielding hand of Titian's Venus. Likewise, the alert black cat at the foot of the bed strikes a sexually rebellious note in contrast to that of the sleeping dog in Titian's portrayal of the goddess in his Venus of Urbino.

Olympia was the subject of caricatures in the popular press, but was championed by the French avant-garde community, and the painting's significance was appreciated by artists such as Gustave Courbet, Paul Cézanne, Claude Monet, and later Paul Gauguin.

As with Luncheon on the Grass, the painting raised the issue of prostitution within contemporary France and the roles of women within society.

Life and times
After the death of his father in 1862, Manet married Suzanne Leenhoff in 1863 at a Protestant church. Leenhoff was a Dutch-born piano teacher two years Manet's senior with whom he had been romantically involved for approximately ten years. Leenhoff initially had been employed by Manet's father, Auguste, to teach Manet and his younger brother piano. She also may have been Auguste's mistress. In 1852, Leenhoff gave birth, out of wedlock, to a son, Leon Koella Leenhoff.

Manet painted his wife in The Reading, among other paintings. Her son, Leon Leenhoff, whose father may have been either of the Manets, posed often for Manet. Most famously, he is the subject of the Boy Carrying a Sword of 1861 (Metropolitan Museum of Art, New York). He also appears as the boy carrying a tray in the background of The Balcony (1868–69).

Manet became friends with the Impressionists Edgar Degas, Claude Monet, Pierre-Auguste Renoir, Alfred Sisley, Paul Cézanne, and Camille Pissarro through another painter, Berthe Morisot, who was a member of the group and drew him into their activities. They later became widely known as the Batignolles group (Le groupe des Batignolles).

The supposed grand-niece of the painter Jean-Honoré Fragonard, Morisot had her first painting accepted in the Salon de Paris in 1864, and she continued to show in the salon for the next ten years.

Manet became the friend and colleague of Morisot in 1868. She is credited with convincing Manet to attempt plein air painting, which she had been practicing since she was introduced to it by another friend of hers, Camille Corot. They had a reciprocating relationship and Manet incorporated some of her techniques into his paintings. In 1874, she became his sister-in-law when she married his brother, Eugène. It has been speculated that there was a repressed love between Manet and Morisot, exemplified by the numerous portraits he did of her before she married his brother.

Unlike the core Impressionist group, Manet maintained that modern artists should seek to exhibit at the Paris Salon rather than abandon it in favor of independent exhibitions. Nevertheless, when Manet was excluded from the International Exhibition of 1867, he set up his own exhibition. His mother worried that he would waste all his inheritance on this project, which was enormously expensive. While the exhibition earned poor reviews from the major critics, it also provided his first contacts with several future Impressionist painters, including Degas.

Although his own work influenced and anticipated the Impressionist style, Manet resisted involvement in Impressionist exhibitions, partly because he did not wish to be seen as the representative of a group identity, and partly because he preferred to exhibit at the Salon. Eva Gonzalès, a daughter of the novelist Emmanuel Gonzalès, was his only formal student.

He was influenced by the Impressionists, especially Monet and Morisot. Their influence is seen in Manet's use of lighter colors: after the early 1870s he made less use of dark backgrounds but retained his distinctive use of black, uncharacteristic of Impressionist painting. He painted many outdoor (plein air) pieces, but always returned to what he considered the serious work of the studio.

Manet enjoyed a close friendship with composer Emmanuel Chabrier, painting two portraits of him; the musician owned 14 of Manet's paintings and dedicated his Impromptu to Manet's wife.

One of Manet's frequent models at the beginning of the 1880s was the "semimondaine" Méry Laurent, who posed for seven portraits in pastel. Laurent's salons hosted many French (and even American) writers and painters of her time; Manet had connections and influence through such events.

Throughout his life, although resisted by art critics, Manet could number as his champions Émile Zola, who supported him publicly in the press, Stéphane Mallarmé, and Charles Baudelaire, who challenged him to depict life as it was. Manet, in turn, drew or painted each of them.

Café scenes

Manet's paintings of café scenes are observations of social life in 19th-century Paris. People are depicted drinking beer, listening to music, flirting, reading, or waiting. Many of these paintings were based on sketches executed on the spot. Manet often visited the Brasserie Reichshoffen on boulevard de Rochechourt, upon which he based At the Cafe in 1878. Several people are at the bar, and one woman confronts the viewer while others wait to be served. Such depictions represent the painted journal of a flâneur. These are painted in a style which is loose, referencing Hals and Velázquez, yet they capture the mood and feeling of Parisian night life. They are painted snapshots of bohemianism, urban working people, as well as some of the bourgeoisie.

In Corner of a Café-Concert, a man smokes while behind him a waitress serves drinks. In The Beer Drinkers a woman enjoys her beer in the company of a friend. In The Café-Concert, shown at right, a sophisticated gentleman sits at a bar while a waitress stands resolutely in the background, sipping her drink. In The Waitress, a serving woman pauses for a moment behind a seated customer smoking a pipe, while a ballet dancer, with arms extended as she is about to turn, is on stage in the background.

Manet also sat at the restaurant on the Avenue de Clichy called Pere Lathuille's, which had a garden in addition to the dining area. One of the paintings he produced here was Chez le père Lathuille (At Pere Lathuille's), in which a man displays an unrequited interest in a woman dining near him.

In Le Bon Bock (1873), a large, cheerful, bearded man sits with a pipe in one hand and a glass of beer in the other, looking straight at the viewer.

Paintings of social activities

Manet painted the upper class enjoying more formal social activities. In Masked Ball at the Opera, Manet shows a lively crowd of people enjoying a party. Men stand with top hats and long black suits while talking to women with masks and costumes. He included portraits of his friends in this picture.

His 1868 painting The Luncheon was posed in the dining room of the Manet house.

Manet depicted other popular activities in his work. In The Races at Longchamp, an unusual perspective is employed to underscore the furious energy of racehorses as they rush toward the viewer. In Skating, Manet shows a well dressed woman in the foreground, while others skate behind her. Always there is the sense of active urban life continuing behind the subject, extending outside the frame of the canvas.

In View of the International Exhibition, soldiers relax, seated and standing, prosperous couples are talking. There is a gardener, a boy with a dog, a woman on horseback—in short, a sample of the classes and ages of the people of Paris.

War

Manet's response to modern life included works devoted to war, in subjects that may be seen as updated interpretations of the genre of "history painting". The first such work was The Battle of the Kearsarge and the Alabama (1864), a sea skirmish known as the Battle of Cherbourg from the American Civil War which took place off the French coast, and may have been witnessed by the artist.

Of interest next was the French intervention in Mexico; from 1867 to 1869 Manet painted three versions of the Execution of Emperor Maximilian, an event which raised concerns regarding French foreign and domestic policy. The several versions of the Execution are among Manet's largest paintings, which suggests that the theme was one which the painter regarded as most important. Its subject is the execution by Mexican firing squad of a Habsburg emperor who had been installed by Napoleon III. Neither the paintings nor a lithograph of the subject were permitted to be shown in France. As an indictment of formalized slaughter, the paintings look back to Goya, and anticipate Picasso's Guernica. During the Franco-Prussian War, Manet served in the National Guard to help defend the city during the siege of Paris, along with Degas. In January 1871, he traveled to Oloron-Sainte-Marie in the Pyrenees. In his absence his friends added his name to the "Fédération des artistes" (see: Courbet) of the Paris Commune. Manet stayed away from Paris, perhaps, until after the semaine sanglante: in a letter to Berthe Morisot at Cherbourg (10 June 1871) he writes, "We came back to Paris a few days ago..." (the semaine sanglante ended on 28 May).

The prints and drawings collection of the Museum of Fine Arts (Budapest) has a watercolour/gouache by Manet, The Barricade, depicting a summary execution of Communards by Versailles troops based on a lithograph of the execution of Maximilian. A similar piece, The Barricade (oil on plywood), is held by a private collector.

On 18 March 1871, he wrote to his (confederate) friend Félix Bracquemond in Paris about his visit to Bordeaux, the provisional seat of the French National Assembly of the Third French Republic where Émile Zola introduced him to the sites: "I never imagined that France could be represented by such doddering old fools, not excepting that little twit Thiers..." If this could be interpreted as support of the Commune, a following letter to Bracquemond (21 March 1871) expressed his idea more clearly: "Only party hacks and the ambitious, the Henrys of this world following on the heels of the Milliéres, the grotesque imitators of the Commune of 1793". He knew the communard Lucien Henry to have been a former painter's model and Millière, an insurance agent. "What an encouragement all these bloodthirsty caperings are for the arts! But there is at least one consolation in our misfortunes: that we're not politicians and have no desire to be elected as deputies".

The public figure Manet admired most was the republican Léon Gambetta. In the heat of the seize mai coup in 1877, Manet opened up his atelier to a republican electoral meeting chaired by Gambetta's friend Eugène Spuller.

Paris
Manet depicted many scenes of the streets of Paris in his works. The Rue Mosnier Decked with Flags depicts red, white, and blue pennants covering buildings on either side of the street; another painting of the same title features a one-legged man walking with crutches. Again depicting the same street, but this time in a different context, is Rue Mosnier with Pavers, in which men repair the roadway while people and horses move past.

The Railway, widely known as The Gare Saint-Lazare, was painted in 1873. The setting is the urban landscape of Paris in the late 19th century. Using his favorite model in his last painting of her, a fellow painter, Victorine Meurent, also the model for Olympia and the Luncheon on the Grass, sits before an iron fence holding a sleeping puppy and an open book in her lap. Next to her is a little girl with her back to the painter, watching a train pass beneath them.

Instead of choosing the traditional natural view as background for an outdoor scene, Manet opts for the iron grating which "boldly stretches across the canvas". The only evidence of the train is its white cloud of steam. In the distance, modern apartment buildings are seen. This arrangement compresses the foreground into a narrow focus. The traditional convention of deep space is ignored.

Historian Isabelle Dervaux has described the reception this painting received when it was first exhibited at the official Paris Salon of 1874: "Visitors and critics found its subject baffling, its composition incoherent, and its execution sketchy. Caricaturists ridiculed Manet's picture, in which only a few recognized the symbol of modernity that it has become today". The painting is currently in the National Gallery of Art in Washington, D.C.

Manet painted several boating subjects in 1874. Boating, now in the Metropolitan Museum of Art, exemplifies in its conciseness the lessons Manet learned from Japanese prints, and the abrupt cropping by the frame of the boat and sail adds to the immediacy of the image.

In 1875, a book-length French edition of Edgar Allan Poe's The Raven included lithographs by Manet and translation by Mallarmé.

In 1881, with pressure from his friend Antonin Proust, the French government awarded Manet the Légion d'honneur.

Late works
In his mid-forties Manet's health deteriorated, and he developed severe pain and partial paralysis in his legs. In 1879 he began receiving hydrotherapy treatments at a spa near Meudon intended to improve what he believed was a circulatory problem, but in reality he was suffering from locomotor ataxia, a known side-effect of syphilis. In 1880, he painted a portrait there of the opera singer Émilie Ambre as Carmen. Ambre and her lover Gaston de Beauplan had an estate in Meudon and had organized the first exhibition of Manet's The Execution of Emperor Maximilian in New York in December 1879.

In his last years Manet painted many small-scale still lifes of fruits and vegetables, such as A Bunch of Asparagus and The Lemon (both 1880). He completed his last major work, A Bar at the Folies-Bergère (Un Bar aux Folies-Bergère), in 1882, and it hung in the Salon that year. Afterwards, he limited himself to small formats.

Manet's last paintings were of flowers in glass vases. There are 20 such paintings known, with the last one painted in March 1883, barely two months before his death. Quoted in Venice thirteen years later, Manet is credited with stating that an artist can say everything he has to say with "flowers, fruit, and clouds." His last flower paintings are a demonstration of that belief.

In 2023, the Metropolitan Museum of Art in New York City exhibited a two-person exhibition of Manet with Degas.

Death
In April 1883, his left foot was amputated because of gangrene caused by complications from syphilis and rheumatism. He died eleven days later on 30 April in Paris. He is buried in the Passy Cemetery in the city.

Legacy
Manet's public career lasted from 1861, the year of his first participation in the Salon, until his death in 1883. His known extant works, as catalogued in 1975 by Denis Rouart and Daniel Wildenstein, comprise 430 oil paintings, 89 pastels, and more than 400 works on paper.

Although harshly condemned by critics who decried its lack of conventional finish, Manet's work had admirers from the beginning. One was Émile Zola, who wrote in 1867: "We are not accustomed to seeing such simple and direct translations of reality. Then, as I said, there is such a surprisingly elegant awkwardness ... it is a truly charming experience to contemplate this luminous and serious painting which interprets nature with a gentle brutality."

The roughly painted style and photographic lighting in Manet's paintings was seen as specifically modern, and as a challenge to the Renaissance works he copied or used as source material. He rejected the technique he had learned in the studio of Thomas Couture – in which a painting was constructed using successive layers of paint on a dark-toned ground – in favor of a direct, alla prima method using opaque paint on a light ground. Novel at the time, this method made possible the completion of a painting in a single sitting. It was adopted by the Impressionists, and became the prevalent method of painting in oils for generations that followed. Manet's work is considered "early modern", partially because of the opaque flatness of his surfaces, the frequent sketch-like passages, and the black outlining of figures, all of which draw attention to the surface of the picture plane and the material quality of paint.

The art historian Beatrice Farwell says Manet "has been universally regarded as the Father of Modernism. With Courbet he was among the first to take serious risks with the public whose favour he sought, the first to make alla prima painting the standard technique for oil painting and one of the first to take liberties with Renaissance perspective and to offer 'pure painting' as a source of aesthetic pleasure. He was a pioneer, again with Courbet, in the rejection of humanistic and historical subject-matter, and shared with Degas the establishment of modern urban life as acceptable material for high art."

Art market
The late Manet painting, Le Printemps (1881), sold to the J. Paul Getty Museum for $65.1 million, setting a new auction record for Manet, exceeding its pre-sale estimate of $25–35 million at Christie's on 5 November 2014. The previous auction record was held by Self-Portrait With Palette which sold for $33.2 million at Sotheby's on 22 June 2010.

Short introductory works

 * One of the friendships is that of Manet and Edgar Degas, pp. 91-176.
 * One of the friendships is that of Manet and Edgar Degas, pp. 91-176.
 * One of the friendships is that of Manet and Edgar Degas, pp. 91-176.

Longer works

 * and

title: Édouard Manet


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Evolutionarily stable strategy

An evolutionarily stable strategy (ESS) is a strategy (or set of strategies) that is impermeable when adopted by a population in adaptation to a specific environment, that is to say it cannot be displaced by an alternative strategy (or set of strategies) which may be novel or initially rare. Introduced by John Maynard Smith and George R. Price in 1972/3, it is an important concept in behavioural ecology, evolutionary psychology, mathematical game theory and economics, with applications in other fields such as anthropology, philosophy and political science.

In game-theoretical terms, an ESS is an equilibrium refinement of the Nash equilibrium, being a Nash equilibrium that is also "evolutionarily stable." Thus, once fixed in a population, natural selection alone is sufficient to prevent alternative (mutant) strategies from replacing it (although this does not preclude the possibility that a better strategy, or set of strategies, will emerge in response to selective pressures resulting from environmental change).

History
Evolutionarily stable strategies were defined and introduced by John Maynard Smith and George R. Price in a 1973 Nature paper. Such was the time taken in peer-reviewing the paper for Nature that this was preceded by a 1972 essay by Maynard Smith in a book of essays titled On Evolution. The 1972 essay is sometimes cited instead of the 1973 paper, but university libraries are much more likely to have copies of Nature. Papers in Nature are usually short; in 1974, Maynard Smith published a longer paper in the Journal of Theoretical Biology. Maynard Smith explains further in his 1982 book Evolution and the Theory of Games. Sometimes these are cited instead. In fact, the ESS has become so central to game theory that often no citation is given, as the reader is assumed to be familiar with it.

Maynard Smith mathematically formalised a verbal argument made by Price, which he read while peer-reviewing Price's paper. When Maynard Smith realized that the somewhat disorganised Price was not ready to revise his article for publication, he offered to add Price as co-author.

The concept was derived from R. H. MacArthur and W. D. Hamilton's work on sex ratios, derived from Fisher's principle, especially Hamilton's (1967) concept of an unbeatable strategy. Maynard Smith was jointly awarded the 1999 Crafoord Prize for his development of the concept of evolutionarily stable strategies and the application of game theory to the evolution of behaviour.

Uses of ESS:
 * The ESS was a major element used to analyze evolution in Richard Dawkins' bestselling 1976 book The Selfish Gene.
 * The ESS was first used in the social sciences by Robert Axelrod in his 1984 book The Evolution of Cooperation. Since then, it has been widely used in the social sciences, including anthropology, economics, philosophy, and political science.
 * In the social sciences, the primary interest is not in an ESS as the end of biological evolution, but as an end point in cultural evolution or individual learning.
 * In evolutionary psychology, ESS is used primarily as a model for human biological evolution.

Motivation
The Nash equilibrium is the traditional solution concept in game theory. It depends on the cognitive abilities of the players. It is assumed that players are aware of the structure of the game and consciously try to predict the moves of their opponents and to maximize their own payoffs. In addition, it is presumed that all the players know this (see common knowledge). These assumptions are then used to explain why players choose Nash equilibrium strategies.

Evolutionarily stable strategies are motivated entirely differently. Here, it is presumed that the players' strategies are biologically encoded and heritable. Individuals have no control over their strategy and need not be aware of the game. They reproduce and are subject to the forces of natural selection, with the payoffs of the game representing reproductive success (biological fitness). It is imagined that alternative strategies of the game occasionally occur, via a process like mutation. To be an ESS, a strategy must be resistant to these alternatives.

Given the radically different motivating assumptions, it may come as a surprise that ESSes and Nash equilibria often coincide. In fact, every ESS corresponds to a Nash equilibrium, but some Nash equilibria are not ESSes.

Nash equilibrium
An ESS is a refined or modified form of a Nash equilibrium. (See the next section for examples which contrast the two.) In a Nash equilibrium, if all players adopt their respective parts, no player can benefit by switching to any alternative strategy. In a two player game, it is a strategy pair. Let E(S,T) represent the payoff for playing strategy S against strategy T. The strategy pair (S, S) is a Nash equilibrium in a two player game if and only if for both players, for any strategy T:
 * E(S,S) ≥ E(T,S)

In this definition, a strategy T≠S can be a neutral alternative to S (scoring equally well, but not better).

A Nash equilibrium is presumed to be stable even if T scores equally, on the assumption that there is no long-term incentive for players to adopt T instead of S. This fact represents the point of departure of the ESS.

Maynard Smith and Price specify two conditions for a strategy S to be an ESS. For all T≠S, either
 * 1) E(S,S) > E(T,S), or
 * 2) E(S,S) = E(T,S) and E(S,T) > E(T,T)

The first condition is sometimes called a strict Nash equilibrium. The second is sometimes called "Maynard Smith's second condition". The second condition means that although strategy T is neutral with respect to the payoff against strategy S, the population of players who continue to play strategy S has an advantage when playing against T.

There is also an alternative, stronger definition of ESS, due to Thomas. This places a different emphasis on the role of the Nash equilibrium concept in the ESS concept. Following the terminology given in the first definition above, this definition requires that for all T≠S

 * 1) E(S,S) ≥ E(T,S), and
 * 2) E(S,T) > E(T,T)

In this formulation, the first condition specifies that the strategy is a Nash equilibrium, and the second specifies that Maynard Smith's second condition is met. Note that the two definitions are not precisely equivalent: for example, each pure strategy in the coordination game below is an ESS by the first definition but not the second.

In words, this definition looks like this: The payoff of the first player when both players play strategy S is higher than (or equal to) the payoff of the first player when he changes to another strategy T and the second player keeps his strategy S and the payoff of the first player when only his opponent changes his strategy to T is higher than his payoff in case that both of players change their strategies to T.

This formulation more clearly highlights the role of the Nash equilibrium condition in the ESS. It also allows for a natural definition of related concepts such as a weak ESS or an evolutionarily stable set.

Examples of differences between Nash equilibria and ESSes
In most simple games, the ESSes and Nash equilibria coincide perfectly. For instance, in the prisoner's dilemma there is only one Nash equilibrium, and its strategy (Defect) is also an ESS.

Some games may have Nash equilibria that are not ESSes. For example, in harm thy neighbor (whose payoff matrix is shown here) both (A, A) and (B, B) are Nash equilibria, since players cannot do better by switching away from either. However, only B is an ESS (and a strong Nash). A is not an ESS, so B can neutrally invade a population of A strategists and predominate, because B scores higher against B than A does against B. This dynamic is captured by Maynard Smith's second condition, since E(A, A) = E(B, A), but it is not the case that E(A,B) > E(B,B).

Nash equilibria with equally scoring alternatives can be ESSes. For example, in the game Harm everyone, C is an ESS because it satisfies Maynard Smith's second condition. D strategists may temporarily invade a population of C strategists by scoring equally well against C, but they pay a price when they begin to play against each other; C scores better against D than does D. So here although E(C, C) = E(D, C), it is also the case that E(C,D) > E(D,D). As a result, C is an ESS.

Even if a game has pure strategy Nash equilibria, it might be that none of those pure strategies are ESS. Consider the Game of chicken. There are two pure strategy Nash equilibria in this game (Swerve, Stay) and (Stay, Swerve). However, in the absence of an uncorrelated asymmetry, neither Swerve nor Stay are ESSes. There is a third Nash equilibrium, a mixed strategy which is an ESS for this game (see Hawk-dove game and Best response for explanation).

This last example points to an important difference between Nash equilibria and ESS. Nash equilibria are defined on strategy sets (a specification of a strategy for each player), while ESS are defined in terms of strategies themselves. The equilibria defined by ESS must always be symmetric, and thus have fewer equilibrium points.

Vs. evolutionarily stable state
In population biology, the two concepts of an evolutionarily stable strategy (ESS) and an evolutionarily stable state are closely linked but describe different situations.

In an evolutionarily stable strategy, if all the members of a population adopt it, no mutant strategy can invade. Once virtually all members of the population use this strategy, there is no 'rational' alternative. ESS is part of classical game theory.

In an evolutionarily stable state, a population's genetic composition is restored by selection after a disturbance, if the disturbance is not too large. An evolutionarily stable state is a dynamic property of a population that returns to using a strategy, or mix of strategies, if it is perturbed from that initial state. It is part of population genetics, dynamical system, or evolutionary game theory. This is now called convergent stability.

B. Thomas (1984) applies the term ESS to an individual strategy which may be mixed, and evolutionarily stable population state to a population mixture of pure strategies which may be formally equivalent to the mixed ESS.

Whether a population is evolutionarily stable does not relate to its genetic diversity: it can be genetically monomorphic or polymorphic.

Stochastic ESS
In the classic definition of an ESS, no mutant strategy can invade. In finite populations, any mutant could in principle invade, albeit at low probability, implying that no ESS can exist. In an infinite population, an ESS can instead be defined as a strategy which, should it become invaded by a new mutant strategy with probability p, would be able to counterinvade from a single starting individual with probability >p, as illustrated by the evolution of bet-hedging.

Prisoner's dilemma
A common model of altruism and social cooperation is the Prisoner's dilemma. Here a group of players would collectively be better off if they could play Cooperate, but since Defect fares better each individual player has an incentive to play Defect. One solution to this problem is to introduce the possibility of retaliation by having individuals play the game repeatedly against the same player. In the so-called iterated Prisoner's dilemma, the same two individuals play the prisoner's dilemma over and over. While the Prisoner's dilemma has only two strategies (Cooperate and Defect), the iterated Prisoner's dilemma has a huge number of possible strategies. Since an individual can have different contingency plan for each history and the game may be repeated an indefinite number of times, there may in fact be an infinite number of such contingency plans.

Three simple contingency plans which have received substantial attention are Always Defect, Always Cooperate, and Tit for Tat. The first two strategies do the same thing regardless of the other player's actions, while the latter responds on the next round by doing what was done to it on the previous round—it responds to Cooperate with Cooperate and Defect with Defect.

If the entire population plays Tit-for-Tat and a mutant arises who plays Always Defect, Tit-for-Tat will outperform Always Defect. If the population of the mutant becomes too large — the percentage of the mutant will be kept small. Tit for Tat is therefore an ESS, with respect to only these two strategies. On the other hand, an island of Always Defect players will be stable against the invasion of a few Tit-for-Tat players, but not against a large number of them. If we introduce Always Cooperate, a population of Tit-for-Tat is no longer an ESS. Since a population of Tit-for-Tat players always cooperates, the strategy Always Cooperate behaves identically in this population. As a result, a mutant who plays Always Cooperate will not be eliminated. However, even though a population of Always Cooperate and Tit-for-Tat can coexist, if there is a small percentage of the population that is Always Defect, the selective pressure is against Always Cooperate, and in favour of Tit-for-Tat. This is due to the lower payoffs of cooperating than those of defecting in case the opponent defects.

This demonstrates the difficulties in applying the formal definition of an ESS to games with large strategy spaces, and has motivated some to consider alternatives.

Human behavior
The fields of sociobiology and evolutionary psychology attempt to explain animal and human behavior and social structures, largely in terms of evolutionarily stable strategies. Sociopathy (chronic antisocial or criminal behavior) may be a result of a combination of two such strategies.

Evolutionarily stable strategies were originally considered for biological evolution, but they can apply to other contexts. In fact, there are stable states for a large class of adaptive dynamics. As a result, they can be used to explain human behaviours that lack any genetic influences.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Evolutionarily stable strategy


text:
Element

Element or elements may refer to:

Science

 * Chemical element, a pure substance of one type of atom
 * Heating element, a device that generates heat by electrical resistance
 * Orbital elements, parameters required to identify a specific orbit of one body around another
 * DNA element, a functional region of DNA, including genes and cis-regulatory elements.

Mathematics

 * Element (category theory)
 * Element (mathematics), one of the constituents of a set
 * Differential element, an infinitesimally small change of a quantity in an integral
 * Euclid's Elements, a mathematical treatise on geometry and number theory
 * An entry, or element, of a matrix.

Philosophy and religion

 * Classical elements, ancient beliefs about the fundamental types of matter (earth, air, fire, water)
 * The elements, a religious term referring to the bread and wine of the Eucharist
 * Godai (Japanese philosophy), the basis of the universe according to Japanese philosophy
 * Mahābhūta, the four great elements in Buddhism, five in Hinduism
 * Tattva, an elemental basis of the universe according to Hindu Samkhya philosophy
 * Wuxing (Chinese philosophy), sometimes translated as five elements, the basis of the universe according to Chinese Taoin

Technology

 * Element (UML), part of the Unified Modeling Language superstructure
 * Data element, a unit of data
 * Electrical element, an abstract part of a circuit
 * HTML element, a standard part of an HTML document
 * Markup element, a part of a document defined by a markup language
 * Structural element, in construction and engineering
 * Adobe Photoshop Elements, a bitmap graphics program
 * Adobe Premiere Elements, a video editing computer program
 * Honda Element, a car
 * Element (software), a Matrix-based chat application formerly known as Riot

Business

 * Element by Westin, a brand of Starwood Hotels and Resorts Worldwide
 * Element Electronics, an American electronics company
 * Element Skateboards, a skateboard manufacturer
 * Elements (restaurant), in Princeton, New Jersey
 * Elements, Hong Kong, a shopping mall in Hong Kong

Music

 * Element (production team), a Norwegian production and songwriting team
 * Elements (band), a 1980s–1990s American jazz band

Albums

 * Elements (Atheist album) or the title song, 1993
 * Elements (B.o.B album), 2016
 * Elements (Elaine album), 2019
 * Elements (Ludovico Einaudi album) or the title song, 2015
 * Elements (Roger Glover album), 1978
 * Elements (Steve Howe album), 2003
 * Elements 1989–1990, by Carl Craig, 1996
 * Elements Box by Mike Oldfield, four CD edition, 1993
 * Elements – The Best of Mike Oldfield, single CD edition, 1993
 * Elements – The Best of Mike Oldfield (video), 1993
 * Elements, by A Band of Boys, 2002
 * Elements, by Yoso, 2010
 * Elements, by Caliban, 2018
 * Elements, by Sister Hazel, 2020
 * Elements, an EP by Vicetone, 2019
 * The Elements (Joe Henderson album), 1974
 * The Elements (Second Person album), 2007
 * The Elements (TobyMac album) or the title song, 2018

Songs

 * "Element" (song), by Kendrick Lamar, 2017
 * "Element", by Deerhunter from Why Hasn't Everything Already Disappeared?, 2019
 * "Element", by Pop Smoke from Meet the Woo 2, 2020
 * "Element", by Vision of Disorder from Vision of Disorder, 1996
 * "Elements", by Matt Corby from Rainbow Valley, 2018
 * "Elements", by Stratovarius from Elements Pt. 1, 2003
 * "The Elements" (song), by Tom Lehrer, 1959
 * "The Elements" (The Beach Boys song), 1966

Other entertainment

 * Element Animation Ltd, a British Mojang-affiliated animation studio
 * Elements (miniseries), a Cartoon Network miniseries
 * Elements trilogy, three films written and directed by Deepa Mehta
 * Elements (esports), a team in the European League of Legends Championship Series
 * Element (sports)

Other

 * Element (criminal law), a basic set of common law principles regarding criminal liability
 * Elements (journal), a scientific publication about mineralogy, geochemistry, and petrology
 * Element Magazine, Asian men's magazine
 * Éléments, French political magazine
 * Elementy, Russian political magazine (1992–2000)
 * The elements, a term used to refer to natural perils such as erosion, rough terrain, rust, cold, heat, and disastrous weather

title: Element


text:
Extremophile

An extremophile is an organism that is able to live (or in some cases thrive) in extreme environments, i.e., environments with conditions approaching or stretching the limits of what known life can adapt to, such as extreme temperature, pressure, radiation, salinity, or pH level.

Since the definition of an extreme environment is relative to an arbitrarily defined standard, often an anthropocentric one, these organisms can be considered ecologically dominant in the evolutionary history of the planet. Some spores and cocooned bacteria samples have been dormant for more than 40 million years; extremophiles have continued to thrive in the most extreme conditions, making them one of the most abundant lifeforms. The study of extremophiles has expanded human knowledge of the limits of life, and informs speculation about extraterrestrial life. Extremophiles are also of interest because of their potential for bioremediation of environments made hazardous to humans due to pollution or contamination.

Characteristics

In the 1980s and 1990s, biologists found that microbial life has great flexibility for surviving in extreme environments—niches that are acidic, extraordinarily hot, or with irregular air pressure for example—that would be completely inhospitable to complex organisms. Some scientists even concluded that life may have begun on Earth in hydrothermal vents far beneath the ocean's surface.

According to astrophysicist Steinn Sigurdsson, "There are viable bacterial spores that have been found that are 40 million years old on Earth—and we know they're very hardened to radiation." Some bacteria were found living in the cold and dark in a lake buried a half-mile deep under the ice in Antarctica, and in the Marianas Trench, the deepest place in Earth's oceans. Expeditions of the International Ocean Discovery Program found microorganisms in 120 C sediment that is 1.2 km below seafloor in the Nankai Trough subduction zone. Some microorganisms have been found thriving inside rocks up to 1900 ft below the sea floor under 8500 ft of ocean off the coast of the northwestern United States. According to one of the researchers, "You can find microbes everywhere—they're extremely adaptable to conditions, and survive wherever they are." A key to extremophile adaptation is their amino acid composition, affecting their protein folding ability under particular conditions. Studying extreme environments on Earth can help researchers understand the limits of habitability on other worlds.

Tom Gheysens from Ghent University in Belgium and some of his colleagues have presented research findings that show spores from a species of Bacillus bacteria survived and were still viable after being heated to temperatures of 420 C.

Classifications
There are many classes of extremophiles that range all around the globe; each corresponding to the way its environmental niche differs from mesophilic conditions. These classifications are not exclusive. Many extremophiles fall under multiple categories and are classified as polyextremophiles. For example, organisms living inside hot rocks deep under Earth's surface are thermophilic and piezophilic such as Thermococcus barophilus. A polyextremophile living at the summit of a mountain in the Atacama Desert might be a radioresistant xerophile, a psychrophile, and an oligotroph. Polyextremophiles are well known for their ability to tolerate both high and low pH levels.

Terms

 * Acidophile: An organism with optimal growth at pH levels of 3.0 or below.

 * Alkaliphile: An organism with optimal growth at pH levels of 9.0 or above.

 * Capnophile: An organism with optimal growth conditions in high concentrations of carbon dioxide. An example would be Mannheimia succiniciproducens, a bacterium that inhabits a ruminant animal's digestive system.

 * Halophile:An organism with optimal growth at a concentration of dissolved salts of 50 g/L (= 5% m/v) or above.

 * Hyperpiezophile:An organism with optimal growth at hydrostatic pressures above 50 MPa (= 493 atm = 7,252 psi).

 * Hyperthermophile:An organism with optimal growth at temperatures above 80 C.

 * Metallotolerant: Capable of tolerating high levels of dissolved heavy metals in solution, such as copper, cadmium, arsenic, and zinc. Examples include Ferroplasma sp., Cupriavidus metallidurans and GFAJ-1.

 * Oligotroph: An organism with optimal growth in nutritionally limited environments.

 * Osmophile: An organism with optimal growth in environments with a high sugar concentration.

 * Piezophile: An organism with optimal growth in hydrostatic pressures above 10 MPa (= 99 atm = 1,450 psi). Also referred to as barophile.

 * Polyextremophile: A polyextremophile (faux Ancient Latin/Greek for 'affection for many extremes') is an organism that qualifies as an extremophile under more than one category.

 * Psychrophile/Cryophile: An organism with optimal growth at temperatures of 15 C or lower.

 * Radioresistant: Organisms resistant to high levels of ionizing radiation, most commonly ultraviolet radiation. This category also includes organisms capable of resisting nuclear radiation.

 * Sulphophile: An organism with optimal growth conditions in high concentrations of sulfur. An example would be Sulfurovum epsilonproteobacteria, a sulfur-oxidizing bacteria that inhabits deep-water sulfur vents.

 * Thermophile: An organism with optimal growth at temperatures above 45 C.

 * Xerophile: An organism with optimal growth at water activity below 0.8.

In astrobiology
Astrobiology is the multidisciplinary field that investigates the deterministic conditions and contingent events with which life arises, distributes, and evolves in the universe. Astrobiology makes use of physics, chemistry, astronomy, solar physics, biology, molecular biology, ecology, planetary science, geography, and geology to investigate the possibility of life on other worlds and help recognize biospheres that might be different from that on Earth. Astrobiologists are particularly interested in studying extremophiles, as it allows them to map what is known about the limits of life on Earth to potential extraterrestrial environments For example, analogous deserts of Antarctica are exposed to harmful UV radiation, low temperature, high salt concentration and low mineral concentration. These conditions are similar to those on Mars. Therefore, finding viable microbes in the subsurface of Antarctica suggests that there may be microbes surviving in endolithic communities and living under the Martian surface. Research indicates it is unlikely that Martian microbes exist on the surface or at shallow depths, but may be found at subsurface depths of around 100 meters.

Recent research carried out on extremophiles in Japan involved a variety of bacteria including Escherichia coli and Paracoccus denitrificans being subject to conditions of extreme gravity. The bacteria were cultivated while being rotated in an ultracentrifuge at high speeds corresponding to 403,627 g (i.e. 403,627 times the gravity experienced on Earth). P. denitrificans was one of the bacteria which displayed not only survival but also robust cellular growth under these conditions of hyperacceleration which are usually found only in cosmic environments, such as on very massive stars or in the shock waves of supernovas. Analysis showed that the small size of prokaryotic cells is essential for successful growth under hypergravity. The research has implications on the feasibility of panspermia.

On 26 April 2012, scientists reported that lichen survived and showed remarkable results on the adaptation capacity of photosynthetic activity within the simulation time of 34 days under Martian conditions in the Mars Simulation Laboratory (MSL) maintained by the German Aerospace Center (DLR).

On 29 April 2013, scientists at Rensselaer Polytechnic Institute, funded by NASA, reported that, during spaceflight on the International Space Station, microbes seem to adapt to the space environment in ways "not observed on Earth" and in ways that "can lead to increases in growth and virulence".

On 19 May 2014, scientists announced that numerous microbes, like Tersicoccus phoenicis, may be resistant to methods usually used in spacecraft assembly clean rooms. It is not currently known if such resistant microbes could have withstood space travel and are present on the Curiosity rover now on the planet Mars.

On 20 August 2014, scientists confirmed the existence of microorganisms living half a mile below the ice of Antarctica.

In September 2015, scientists from CNR-National Research Council of Italy reported that S. soflataricus was able to survive under Martian radiation at a wavelength that was considered extremely lethal to most bacteria. This discovery is significant because it indicates that not only bacterial spores, but also growing cells can be remarkably resistant to strong UV radiation.

In June 2016, scientists from Brigham Young University conclusively reported that endospores of Bacillus subtilis were able to survive high speed impacts up to 299±28 m/s, extreme shock, and extreme deceleration. They pointed out that this feature might allow endospores to survive and to be transferred between planets by traveling within meteorites or by experiencing atmosphere disruption. Moreover, they suggested that the landing of spacecraft may also result in interplanetary spore transfer, given that spores can survive high-velocity impact while ejected from the spacecraft onto the planet surface. This is the first study which reported that bacteria can survive in such high-velocity impact. However, the lethal impact speed is unknown, and further experiments should be done by introducing higher-velocity impact to bacterial endospores.

In August 2020 scientists reported that bacteria that feed on air discovered 2017 in Antarctica are likely not limited to Antarctica after discovering the two genes previously linked to their "atmospheric chemosynthesis" in soil of two other similar cold desert sites, which provides further information on this carbon sink and further strengthens the extremophile evidence that supports the potential existence of microbial life on alien planets.

The same month, scientists reported that bacteria from Earth, particularly Deinococcus radiodurans, were found to survive for three years in outer space, based on studies on the International Space Station. These findings support the notion of panspermia.

Bioremediation
Extremophiles can also be useful players in the bioremediation of contaminated sites as some species are capable of biodegradation under conditions too extreme for classic bioremediation candidate species. Anthropogenic activity causes the release of pollutants that may potentially settle in extreme environments as is the case with tailings and sediment released from deep-sea mining activity. While most bacteria would be crushed by the pressure in these environments, piezophiles can tolerate these depths and can metabolize pollutants of concern if they possess bioremediation potential.

Hydrocarbons
There are multiple potential destinations for hydrocarbons after an oil spill has settled and currents routinely deposit them in extreme environments. Methane bubbles resulting from the Deepwater Horizon oil spill were found 1.1 kilometers below water surface level and at concentrations as high as 183 μmol per kilogram. The combination of low temperatures and high pressures in this environment result in low microbial activity. However, bacteria that are present including species of Pseudomonas, Aeromonas and Vibrio were found to be capable of bioremediation, albeit at a tenth of the speed they would perform at sea level pressure. Polycyclic aromatic hydrocarbons increase in solubility and bioavailability with increasing temperature. Thermophilic Thermus and Bacillus species have demonstrated higher gene expression for the alkane mono-oxygenase alkB at temperatures exceeding 60 C. The expression of this gene is a crucial precursor to the bioremediation process. Fungi that have been genetically modified with cold-adapted enzymes to tolerate differing pH levels and temperatures have been shown to be effective at remediating hydrocarbon contamination in freezing conditions in the Antarctic.

Metals
Acidithiubacillus ferroxidans has been shown to be effective in remediating mercury in acidic soil due to its merA gene making it mercury resistant. Industrial effluent contain high levels of metals that can be detrimental to both human and ecosystem health. In extreme heat environments the extremophile Geobacillus thermodenitrificans has been shown to effectively manage the concentration of these metals within twelve hours of introduction. Some acidophilic microorganisms are effective at metal remediation in acidic environments due to proteins found in their periplasm, not present in any mesophilic organisms, allowing them to protect themselves from high proton concentrations. Rice paddies are highly oxidative environments that can produce high levels of lead or cadmium. Deinococcus radiodurans are resistant to the harsh conditions of the environment and are therefore candidate species for limiting the extent of contamination of these metals.

Some bacteria are known to also use rare earth elements on their biological processes. For example, Methylacidiphilum fumariolicum, Methylorubrum extorquens, and Methylobacterium radiotolerans are known to be able to use lanthanides as cofactors to increase their methanol dehydrogenase activity.

Acid mine drainage
Acid mine drainage is a major environmental concern associated with many metal mines. This is due to the fact that this highly acidic water can mix with groundwater, streams, and lakes. The drainage turns the pH in these water sources from a more neutral pH to a pH lower than 4. This is close to the acidity levels of battery acid or stomach acid. Exposure to the polluted water can greatly affect the health of plants, humans, and animals. However, a productive method of remediation is to introduce the extremophile, Thiobacillus ferrooxidans. This extremophile is useful for its bioleaching property. It helps to break down minerals in the waste water created by the mine. By breaking down the minerals Thiobacillus ferrooxidans start to help neutralize the acidity of the waste water. This is a way to reduce the environmental impact and help remediate the damage caused by the acid mine drainage leaks.

Oil-based, hazardous pollutants in Arctic regions
Psychrophilic microbes metabolize hydrocarbons which assists in the remediation of hazardous, oil-based pollutants in the Arctic and Antarctic regions. These specific microbes are used in this region due to their ability to perform their functions at extremely cold temperatures.

Radioactive materials
Any bacteria capable of inhabiting radioactive mediums can be classified as an extremophile. Radioresistant organisms are therefore critical in the bioremediation of radionuclides. Uranium is particularly challenging to contain when released into an environment and very harmful to both human and ecosystem health. The NANOBINDERS project is equipping bacteria that can survive in uranium rich environments with gene sequences that enable proteins to bind to uranium in mining effluent, making it more convenient to collect and dispose of. Some examples are Shewanella putrefaciens, Geobacter metallireducens and some strains of Burkholderia fungorum.

Radiotrophic fungi, which use radiation as an energy source, have been found inside and around the Chernobyl Nuclear Power Plant.

Radioresistance has also been observed in certain species of macroscopic lifeforms. The lethal dose required to kill up to 50% of a tortoise population is 40,000 roentgens, compared to only 800 roentgens needed to kill 50% of a human population. In experiments exposing lepidopteran insects to gamma radiation, significant DNA damage was detected only at 20 Gy and higher doses, in contrast with human cells that showed similar damage at only 2 Gy.

Examples and recent findings
New sub-types of extremophiles are identified frequently and the sub-category list for extremophiles is always growing. For example, microbial life lives in the liquid asphalt lake, Pitch Lake. Research indicates that extremophiles inhabit the asphalt lake in populations ranging between 106 and 107 cells/gram. Likewise, until recently, boron tolerance was unknown, but a strong borophile was discovered in bacteria. With the recent isolation of Bacillus boroniphilus, borophiles came into discussion. Studying these borophiles may help illuminate the mechanisms of both boron toxicity and boron deficiency.

In July 2019, a scientific study of Kidd Mine in Canada discovered sulfur-breathing organisms which live 7900 ft below the surface, and which breathe sulfur in order to survive. These organisms are also remarkable due to eating rocks such as pyrite as their regular food source.

Biotechnology
The thermoalkaliphilic catalase, which initiates the breakdown of hydrogen peroxide into oxygen and water, was isolated from an organism, Thermus brockianus, found in Yellowstone National Park by Idaho National Laboratory researchers. The catalase operates over a temperature range from 30 °C to over 94 °C and a pH range from 6–10. This catalase is extremely stable compared to other catalases at high temperatures and pH. In a comparative study, the T. brockianus catalase exhibited a half life of 15 days at 80 °C and pH 10 while a catalase derived from Aspergillus niger had a half life of 15 seconds under the same conditions. The catalase will have applications for removal of hydrogen peroxide in industrial processes such as pulp and paper bleaching, textile bleaching, food pasteurization, and surface decontamination of food packaging.

DNA modifying enzymes such as Taq DNA polymerase and some Bacillus enzymes used in clinical diagnostics and starch liquefaction are produced commercially by several biotechnology companies.

DNA transfer
Over 65 prokaryotic species are known to be naturally competent for genetic transformation, the ability to transfer DNA from one cell to another cell followed by integration of the donor DNA into the recipient cell's chromosome. Several extremophiles are able to carry out species-specific DNA transfer, as described below. However, it is not yet clear how common such a capability is among extremophiles.

The bacterium Deinococcus radiodurans is one of the most radioresistant organisms known. This bacterium can also survive cold, dehydration, vacuum and acid and is thus known as a polyextremophile. D. radiodurans is competent to perform genetic transformation. Recipient cells are able to repair DNA damage in donor transforming DNA that had been UV irradiated as efficiently as they repair cellular DNA when the cells themselves are irradiated. The extreme thermophilic bacterium Thermus thermophilus and other related Thermus species are also capable of genetic transformation.

Halobacterium volcanii, an extreme halophilic (saline tolerant) archaeon, is capable of natural genetic transformation. Cytoplasmic bridges are formed between cells that appear to be used for DNA transfer from one cell to another in either direction.

Sulfolobus solfataricus and Sulfolobus acidocaldarius are hyperthermophilic archaea. Exposure of these organisms to the DNA damaging agents UV irradiation, bleomycin or mitomycin C induces species-specific cellular aggregation. UV-induced cellular aggregation of S. acidocaldarius mediates chromosomal marker exchange with high frequency. Recombination rates exceed those of uninduced cultures by up to three orders of magnitude. Frols et al. and Ajon et al. hypothesized that cellular aggregation enhances species-specific DNA transfer between Sulfolobus cells in order to repair damaged DNA by means of homologous recombination. Van Wolferen et al. noted that this DNA exchange process may be crucial under DNA damaging conditions such as high temperatures. It has also been suggested that DNA transfer in Sulfolobus may be an early form of sexual interaction similar to the more well-studied bacterial transformation systems that involve species-specific DNA transfer leading to homologous recombinational repair of DNA damage (and see Transformation (genetics)).

Extracellular membrane vesicles (MVs) might be involved in DNA transfer between different hyperthermophilic archaeal species. It has been shown that both plasmids and viral genomes can be transferred via MVs. Notably, a horizontal plasmid transfer has been documented between hyperthermophilic Thermococcus and Methanocaldococcus species, respectively belonging to the orders Thermococcales and Methanococcales.

title: Extremophile