title: Rain

text: The phrase "acid rain" was first used by Scottish chemist Robert Augus Smith in 1852. The pH of rain varies, especially due to its origin. On America's East Coast, rain that is derived from the Atlantic Ocean typically has a pH of 5.0–5.6; rain that comes across the continental from the west has a pH of 3.8–4.8; and local thunderstorms can have a pH as low as 2.0. Rain becomes acidic primarily due to the presence of two strong acids, sulfuric acid (HSO) and nitric acid (HNO). Sulfuric acid is derived from natural sources such as volcanoes, and wetlands (sulfate reducing bacteria); and anthropogenic sources such as the combustion of fossil fuels, and mining where HS is present. Nitric acid is produced by natural sources such as lightning, soil bacteria, and natural fires; while also produced anthropogenically by the combustion of fossil fuels and from power plants. In the past 20 years the concentrations of nitric and sulfuric acid has decreased in presence of rainwater, which may be due to the significant increase in ammonium (most likely as ammonia from livestock production), which acts as a buffer in acid rain and raises the pH.


title: Rain

text: The Köppen classification depends on average monthly values of temperature and precipitation. The most commonly used form of the Köppen classification has five primary types labeled A through E. Specifically, the primary types are A, tropical; B, dry; C, mild mid-latitude; D, cold mid-latitude; and E, polar. The five primary classifications can be further divided into secondary classifications such as rain forest, monsoon, tropical savanna, humid subtropical, humid continental, oceanic climate, Mediterranean climate, steppe, subarctic climate, tundra, polar ice cap, and desert.


title: Rain

text: Rain forests are characterized by high rainfall, with definitions setting minimum normal annual rainfall between . A tropical savanna is a grassland biome located in semi-arid to semi-humid climate regions of subtropical and tropical latitudes, with rainfall between a year. They are widespread on Africa, and are also found in India, the northern parts of South America, Malaysia, and Australia. The humid subtropical climate zone is where winter rainfall is associated with large storms that the westerlies steer from west to east. Most summer rainfall occurs during thunderstorms and from occasional tropical cyclones. Humid subtropical climates lie on the east side continents, roughly between latitudes 20° and 40° degrees away from the equator.


title: Rain

text: An oceanic (or maritime) climate is typically found along the west coasts at the middle latitudes of all the world's continents, bordering cool oceans, as well as southeastern Australia, and is accompanied by plentiful precipitation year-round. The Mediterranean climate regime resembles the climate of the lands in the Mediterranean Basin, parts of western North America, parts of Western and South Australia, in southwestern South Africa and in parts of central Chile. The climate is characterized by hot, dry summers and cool, wet winters. A steppe is a dry grassland. Subarctic climates are cold with continuous permafrost and little precipitation.


title: Rain

text: Rain is measured in units of length per unit time, typically in millimeters per hour, or in countries where imperial units are more common, inches per hour. The "length", or more accurately, "depth" being measured is the depth of rain water that would accumulate on a flat, horizontal and impermeable surface during a given amount of time, typically an hour. One millimeter of rainfall is the equivalent of one liter of water per square meter.


title: Rain

text: The standard way of measuring rainfall or snowfall is the standard rain gauge, which can be found in 100-mm (4-in) plastic and 200-mm (8-in) metal varieties. The inner cylinder is filled by of rain, with overflow flowing into the outer cylinder. Plastic gauges have markings on the inner cylinder down to resolution, while metal gauges require use of a stick designed with the appropriate markings. After the inner cylinder is filled, the amount inside it is discarded, then filled with the remaining rainfall in the outer cylinder until all the fluid in the outer cylinder is gone, adding to the overall total until the outer cylinder is empty. Other types of gauges include the popular wedge gauge (the cheapest rain gauge and most fragile), the tipping bucket rain gauge, and the weighing rain gauge. For those looking to measure rainfall the most inexpensively, a can that is cylindrical with straight sides will act as a rain gauge if left out in the open, but its accuracy will depend on what ruler is used to measure the rain with. Any of the above rain gauges can be made at home, with enough know-how.


title: Rain

text: When a precipitation measurement is made, various networks exist across the United States and elsewhere where rainfall measurements can be submitted through the Internet, such as CoCoRAHS or GLOBE. If a network is not available in the area where one lives, the nearest local weather or met office will likely be interested in the measurement.


title: Rain

text: One of the main uses of weather radar is to be able to assess the amount of precipitations fallen over large basins for hydrological purposes. For instance, river flood control, sewer management and dam construction are all areas where planners use rainfall accumulation data. Radar-derived rainfall estimates complement surface station data which can be used for calibration. To produce radar accumulations, rain rates over a point are estimated by using the value of reflectivity data at individual grid points. A radar equation is then used, which is


title: Rain

text: where Z represents the radar reflectivity, R represents the rainfall rate, and A and b are constants.


title: Rain

text: Satellite derived rainfall estimates use passive microwave instruments aboard polar orbiting as well as geostationary weather satellites to indirectly measure rainfall rates. If one wants an accumulated rainfall over a time period, one has to add up all the accumulations from each grid box within the images during that time.


title: Rain

text: Rainfall intensity is classified according to the rate of precipitation, which depends on the considered time. The following categories are used to classify rainfall intensity:


title: Rain

text: The intensity can also be expressed by rainfall erosivity "R-factor" or in terms of the rainfall time-structure "n-index".


title: Rain

text: The average time between occurrences of an event with a specified intensity and duration is called the return period. The intensity of a storm can be predicted for any return period and storm duration, from charts based on historic data for the location. The return period is often expressed as an "n"-year event. For instance, a 10-year storm describes a rare rainfall event occurring on average once every 10 years. The rainfall will be greater and the flooding will be worse than the worst storm expected in any single year. A 100-year storm describes an extremely rare rainfall event occurring on average once in a century. The rainfall will be extreme and flooding worse than a 10-year event. The probability of an event in any year is the inverse of the return period (assuming the probability remains the same for each year). For instance a 10-year storm has a probability of occurring of 10 percent in any given year, and a 100-year storm occurs with a 1 percent probability in a year. As with all probability events, it is possible, though improbable, to have multiple 100-year storms in a single year.


title: Rain

text: The Quantitative Precipitation Forecast (abbreviated QPF) is the expected amount of liquid precipitation accumulated over a specified time period over a specified area. A QPF will be specified when a measurable precipitation type reaching a minimum threshold is forecast for any hour during a QPF valid period. Precipitation forecasts tend to be bound by synoptic hours such as 0000, 0600, 1200 and 1800 GMT. Terrain is considered in QPFs by use of topography or based upon climatological precipitation patterns from observations with fine detail. Starting in the mid to late 1990s, QPFs were used within hydrologic forecast models to simulate impact to rivers throughout the United States.


title: Rain

text: Forecast models show significant sensitivity to humidity levels within the planetary boundary layer, or in the lowest levels of the atmosphere, which decreases with height. QPF can be generated on a quantitative, forecasting amounts, or a qualitative, forecasting the probability of a specific amount, basis. Radar imagery forecasting techniques show higher skill than model forecasts within 6 to 7 hours of the time of the radar image. The forecasts can be verified through use of rain gauge measurements, weather radar estimates, or a combination of both. Various skill scores can be determined to measure the value of the rainfall forecast.


title: Rain

text: Precipitation, especially rain, has a dramatic effect on agriculture. All plants need at least some water to survive, therefore rain (being the most effective means of watering) is important to agriculture. While a regular rain pattern is usually vital to healthy plants, too much or too little rainfall can be harmful, even devastating to crops. Drought can kill crops and increase erosion, while overly wet weather can cause harmful fungus growth. Plants need varying amounts of rainfall to survive. For example, certain cacti require small amounts of water, while tropical plants may need up to hundreds of inches of rain per year to survive.


title: Rain

text: In areas with wet and dry seasons, soil nutrients diminish and erosion increases during the wet season. Animals have adaptation and survival strategies for the wetter regime. The previous dry season leads to food shortages into the wet season, as the crops have yet to mature. Developing countries have noted that their populations show seasonal weight fluctuations due to food shortages seen before the first harvest, which occurs late in the wet season. Rain may be harvested through the use of rainwater tanks; treated to potable use or for non-potable use indoors or for irrigation. Excessive rain during short periods of time can cause flash floods.


title: Rain

text: Cultural attitudes towards rain differ across the world. In temperate climates, people tend to be more stressed when the weather is unstable or cloudy, with its impact greater on men than women. Rain can also bring joy, as some consider it to be soothing or enjoy the aesthetic appeal of it. In dry places, such as India, or during periods of drought, rain lifts people's moods. In Botswana, the Setswana word for rain, "pula", is used as the name of the national currency, in recognition of the economic importance of rain in its country, since it has a desert climate. Several cultures have developed means of dealing with rain and have developed numerous protection devices such as umbrellas and raincoats, and diversion devices such as gutters and storm drains that lead rains to sewers. Many people find the scent during and immediately after rain pleasant or distinctive. The source of this scent is petrichor, an oil produced by plants, then absorbed by rocks and soil, and later released into the air during rainfall.


title: Rain

text: Rain holds an important religious significance in many cultures. The ancient Sumerians believed that rain was the semen of the sky-god An, which fell from the heavens to inseminate his consort, the earth-goddess Ki, causing her to give birth to all the plants of the earth. The Akkadians believed that the clouds were the breasts of Anu's consort Antu and that rain was milk from her breasts. According to Jewish tradition, in the first century BC, the Jewish miracle-worker Honi ha-M'agel ended a three-year drought in Judaea by drawing a circle in the sand and praying for rain, refusing to leave the circle until his prayer was granted. In his "Meditations", the Roman emperor Marcus Aurelius preserves a prayer for rain made by the Athenians to the Greek sky-god Zeus. Various Native American tribes are known to have historically conducted rain dances in effort to encourage rainfall. Rainmaking rituals are also important in many African cultures. In the present-day United States, various state governors have held Days of Prayer for rain, including the Days of Prayer for Rain in the State of Texas in 2011.


title: Rain

text: Approximately of water falls as precipitation each year across the globe with of it over the oceans. Given the Earth's surface area, that means the globally averaged annual precipitation is . Deserts are defined as areas with an average annual precipitation of less than per year, or as areas where more water is lost by evapotranspiration than falls as precipitation.


title: Rain

text: The northern half of Africa is dominated by the world's most extensive hot, dry region, the Sahara Desert. Some deserts also occupy much of southern Africa: the Namib and the Kalahari. Across Asia, a large annual rainfall minimum, composed primarily of deserts, stretches from the Gobi Desert in Mongolia west-southwest through western Pakistan (Balochistan) and Iran into the Arabian Desert in Saudi Arabia. Most of Australia is semi-arid or desert, making it the world's driest inhabited continent. In South America, the Andes mountain range blocks Pacific moisture that arrives in that continent, resulting in a desertlike climate just downwind across western Argentina. The drier areas of the United States are regions where the Sonoran Desert overspreads the Desert Southwest, the Great Basin and central Wyoming.


title: Rain

text: Since rain only falls as liquid, it rarely falls when surface temperatures are below freezing, unless there is a layer of warm air aloft, in which case it becomes freezing rain. Due to the entire atmosphere being below freezing most of the time, very cold climates see very little rainfall and are often known as polar deserts. A common biome in this area is the tundra which has a short summer thaw and a long frozen winter. Ice caps see no rain at all, making Antarctica the world's driest continent.


title: Rain

text: Rainforests are areas of the world with very high rainfall. Both tropical and temperate rainforests exist. Tropical rainforests occupy a large band of the planet mostly along the equator. Most temperate rainforests are located on mountainous west coasts between 45 and 55 degrees latitude, but they are often found in other areas.


title: Rain

text: Around 40–75% of all biotic life is found in rainforests. Rainforests are also responsible for 28% of the world's oxygen turnover.


title: Rain

text: The equatorial region near the Intertropical Convergence Zone (ITCZ), or monsoon trough, is the wettest portion of the world's continents. Annually, the rain belt within the tropics marches northward by August, then moves back southward into the Southern Hemisphere by February and March. Within Asia, rainfall is favored across its southern portion from India east and northeast across the Philippines and southern China into Japan due to the monsoon advecting moisture primarily from the Indian Ocean into the region. The monsoon trough can reach as far north as the 40th parallel in East Asia during August before moving southward thereafter. Its poleward progression is accelerated by the onset of the summer monsoon which is characterized by the development of lower air pressure (a thermal low) over the warmest part of Asia. Similar, but weaker, monsoon circulations are present over North America and Australia. During the summer, the Southwest monsoon combined with Gulf of California and Gulf of Mexico moisture moving around the subtropical ridge in the Atlantic Ocean bring the promise of afternoon and evening thunderstorms to the southern tier of the United States as well as the Great Plains. The eastern half of the contiguous United States east of the 98th meridian, the mountains of the Pacific Northwest, and the Sierra Nevada range are the wetter portions of the nation, with average rainfall exceeding per year. Tropical cyclones enhance precipitation across southern sections of the United States, as well as Puerto Rico, the United States Virgin Islands, the Northern Mariana Islands, Guam, and American Samoa.


title: Rain

text: Westerly flow from the mild north Atlantic leads to wetness across western Europe, in particular Ireland and the United Kingdom, where the western coasts can receive between , at sea level and , on the mountains of rain per year. Bergen, Norway is one of the more famous European rain-cities with its yearly precipitation of on average. During the fall, winter, and spring, Pacific storm systems bring most of Hawaii and the western United States much of their precipitation. Over the top of the ridge, the jet stream brings a summer precipitation maximum to the Great Lakes. Large thunderstorm areas known as mesoscale convective complexes move through the Plains, Midwest, and Great Lakes during the warm season, contributing up to 10% of the annual precipitation to the region.


title: Rain

text: The El Niño-Southern Oscillation affects the precipitation distribution, by altering rainfall patterns across the western United States, Midwest, the Southeast, and throughout the tropics. There is also evidence that global warming is leading to increased precipitation to the eastern portions of North America, while droughts are becoming more frequent in the tropics and subtropics.


title: Rain

text: Cherrapunji, situated on the southern slopes of the Eastern Himalaya in Shillong, India is the confirmed wettest place on Earth, with an average annual rainfall of . The highest recorded rainfall in a single year was in 1861. The 38-year average at nearby Mawsynram, Meghalaya, India is . The wettest spot in Australia is Mount Bellenden Ker in the north-east of the country which records an average of per year, with over of rain recorded during 2000. The Big Bog on the island of Maui has the highest average annual rainfall in the Hawaiian Islands, at . Mount Waiʻaleʻale on the island of Kauaʻi achieves similar torrential rains, while slightly lower than that of the Big Bog, at of rain per year over the last 32 years, with a record in 1982. Its summit is considered one of the rainiest spots on earth, with a reported 350 days of rain per year.


title: Rain

text: Lloró, a town situated in Chocó, Colombia, is probably the place with the largest rainfall in the world, averaging per year. The Department of Chocó is extraordinarily humid. Tutunendaó, a small town situated in the same department, is one of the wettest estimated places on Earth, averaging per year; in 1974 the town received , the largest annual rainfall measured in Colombia. Unlike Cherrapunji, which receives most of its rainfall between April and September, Tutunendaó receives rain almost uniformly distributed throughout the year. Quibdó, the capital of Chocó, receives the most rain in the world among cities with over 100,000 inhabitants: per year. Storms in Chocó can drop of rainfall in a day. This amount is more than what falls in many cities in a year's time.


title: Rain

text: Rainfalls of diamonds have been suggested to occur on the gas giant planets, Jupiter and Saturn, as well as on the ice giant planets, Uranus and Neptune. There is likely to be rain of various compositions in the upper atmospheres of the gas giants, as well as precipitation of liquid neon in the deep atmospheres. On Titan, Saturn's largest natural satellite, infrequent methane rain is thought to carve the moon's numerous surface channels. On Venus, sulfuric acid virga evaporates from the surface. Extrasolar planet OGLE-TR-56b in the constellation Sagittarius is hypothesized to have iron rain. Accordingly, research carried out by the European Southern Observatory shows that WASP-76b can produce showers of burning liquid iron droplets once temperature decreases during the planet's night hours. There is evidence from samples of basalt brought back by the Apollo missions that the Moon has been subject to lava rain.


title: Natural selection

text: 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.


title: Natural selection

text: 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 (now often included in natural selection) and fecundity selection.


title: Natural selection

text: Natural selection acts on the phenotype, the characteristics of the organism which actually interact with the environment, but the genetic


title: Natural selection

text: (heritable) basis of any phenotype that gives that phenotype a reproductive advantage may become more common in a population. Over time, this process can result in populations that specialise for particular ecological niches (microevolution) and may eventually result in speciation (the emergence of new species, macroevolution). In other words, natural selection is a key process in the evolution of a population.


title: Natural selection

text: Natural selection is a cornerstone of modern biology. The concept, published by Darwin and Alfred Russel Wallace in a joint presentation of papers in 1858, was elaborated in Darwin's influential 1859 book "On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life". He described natural selection as analogous to artificial selection, a process by which animals and plants with traits considered desirable by human breeders are systematically favoured for reproduction. The concept of natural selection originally developed in the absence of a valid theory of heredity; at the time of Darwin's writing, science had yet to develop modern theories of genetics. The union of traditional Darwinian evolution with subsequent discoveries in classical genetics formed the modern synthesis of the mid-20th century. The addition of molecular genetics has led to evolutionary developmental biology, which explains evolution at the molecular level. While genotypes can slowly change by random genetic drift, natural selection remains the primary explanation for adaptive evolution.


title: Natural selection

text: 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:


title: Natural selection

text: 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:


title: Natural selection

text: The classical arguments were reintroduced in the 18th century by Pierre Louis Maupertuis and others, including Darwin's grandfather, Erasmus Darwin.


title: Natural selection

text: 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.


title: Natural selection

text: 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 antagonism to mainstream genetic theory as late as the mid 20th century.


title: Natural selection

text: Between 1835 and 1837, the zoologist Edward Blyth worked on the area of variation, artificial selection, and how a similar process occurs in nature. Darwin acknowledged Blyth's ideas in the first chapter on variation of "On the Origin of Species".


title: Natural selection

text: In 1859, Charles Darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. He defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved". The concept was simple but powerful: individuals best adapted to their environments are more likely to survive and reproduce. As long as there is some variation between them and that variation is heritable, there will be an inevitable selection of individuals with the most advantageous variations. If the variations are heritable, then differential reproductive success leads to the evolution of particular populations of a species, and populations that evolve to be sufficiently different eventually become different species.


title: Natural selection

text: Darwin's ideas were inspired by the observations that he had made on the second voyage of HMS "Beagle" (1831–1836), and by the work of a political economist, Thomas Robert Malthus, who, in "An Essay on the Principle of Population" (1798), noted that population (if unchecked) increases exponentially, whereas the food supply grows only arithmetically; thus, inevitable limitations of resources would have demographic implications, leading to a "struggle for existence". When Darwin read Malthus in 1838 he was already primed by his work as a naturalist to appreciate the "struggle for existence" in nature. It struck him that as population outgrew resources, "favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The result of this would be the formation of new species." Darwin wrote:


title: Natural selection

text: Once he had his theory, Darwin was meticulous about gathering and refining evidence before making his idea public. He was in the process of writing his "big book" to present his research when the naturalist Alfred Russel Wallace independently conceived of the principle and described it in an essay he sent to Darwin to forward to Charles Lyell. Lyell and Joseph Dalton Hooker decided to present his essay together with unpublished writings that Darwin had sent to fellow naturalists, and "On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection" was read to the Linnean Society of London announcing co-discovery of the principle in July 1858. Darwin published a detailed account of his evidence and conclusions in "On the Origin of Species" in 1859. In the 3rd edition of 1861 Darwin acknowledged that others—like William Charles Wells in 1813, and Patrick Matthew in 1831—had proposed similar ideas, but had neither developed them nor presented them in notable scientific publications.


title: Natural selection

text: Darwin thought of natural selection by analogy to how farmers select crops or livestock for breeding, which he called "artificial selection"; in his early manuscripts he referred to a "Nature" which would do the selection. At the time, other mechanisms of evolution such as evolution by genetic drift were not yet explicitly formulated, and Darwin believed that selection was likely only part of the story: "I am convinced that Natural Selection has been the main but not exclusive means of modification." In a letter to Charles Lyell in September 1860, Darwin regretted the use of the term "Natural Selection", preferring the term "Natural Preservation".


title: Natural selection

text: For Darwin and his contemporaries, natural selection was in essence synonymous with evolution by natural selection. After the publication of "On the Origin of Species", educated people generally accepted that evolution had occurred in some form. However, natural selection remained controversial as a mechanism, partly because it was perceived to be too weak to explain the range of observed characteristics of living organisms, and partly because even supporters of evolution balked at its "unguided" and non-progressive nature, a response that has been characterised as the single most significant impediment to the idea's acceptance. However, some thinkers enthusiastically embraced natural selection; after reading Darwin, Herbert Spencer introduced the phrase "survival of the fittest", which became a popular summary of the theory. The fifth edition of "On the Origin of Species" published in 1869 included Spencer's phrase as an alternative to natural selection, with credit given: "But the expression often used by Mr. Herbert Spencer of the Survival of the Fittest is more accurate, and is sometimes equally convenient." Although the phrase is still often used by non-biologists, modern biologists avoid it because it is tautological if "fittest" is read to mean "functionally superior" and is applied to individuals rather than considered as an averaged quantity over populations.


title: Natural selection

text: Natural selection relies crucially on the idea of heredity, but developed before the basic concepts of genetics. Although the Moravian monk Gregor Mendel, the father of modern genetics, was a contemporary of Darwin's, his work lay in obscurity, only being rediscovered in 1900. With the early 20th century integration of evolution with Mendel's laws of inheritance, the so-called modern synthesis, scientists generally came to accept natural selection. The synthesis grew from advances in different fields. Ronald Fisher developed the required mathematical language and wrote "The Genetical Theory of Natural Selection" (1930). J. B. S. Haldane introduced the concept of the "cost" of natural selection.


title: Natural selection

text: In his book "Genetics and the Origin of Species" (1937), Theodosius Dobzhansky established the idea that mutation, once seen as a rival to selection, actually supplied the raw material for natural selection by creating genetic diversity.


title: Natural selection

text: Ernst Mayr recognised the key importance of reproductive isolation for speciation in his "Systematics and the Origin of Species" (1942).


title: Natural selection

text: W. D. Hamilton conceived of kin selection in 1964. This synthesis cemented natural selection as the foundation of evolutionary theory, where it remains today. A second synthesis was brought about at the end of the 20th century by advances in molecular genetics, creating the field of evolutionary developmental biology ("evo-devo"), which seeks to explain the evolution of form in terms of the genetic regulatory programs which control the development of the embryo at molecular level. Natural selection is here understood to act on embryonic development to change the morphology of the adult body.


title: Natural selection

text: The term "natural selection" is most often defined to operate on heritable traits, because these directly participate in evolution. However, natural selection is "blind" in the sense that changes in phenotype can give a reproductive advantage regardless of whether or not the trait is heritable. Following Darwin's primary usage, the term is used to refer both to the evolutionary consequence of blind selection and to its mechanisms. It is sometimes helpful to explicitly distinguish between selection's mechanisms and its effects; when this distinction is important, scientists define "(phenotypic) natural selection" specifically as "those mechanisms that contribute to the selection of individuals that reproduce", without regard to whether the basis of the selection is heritable. Traits that cause greater reproductive success of an organism are said to be "selected for", while those that reduce success are "selected against".


title: Natural selection

text: Natural variation occurs among the individuals of any population of organisms. Some differences may improve an individual's chances of surviving and reproducing such that its lifetime reproductive rate is increased, which means that it leaves more offspring. If the traits that give these individuals a reproductive advantage are also heritable, that is, passed from parent to offspring, then there will be differential reproduction, that is, a slightly higher proportion of fast rabbits or efficient algae in the next generation. Even if the reproductive advantage is very slight, over many generations any advantageous heritable trait becomes dominant in the population. In this way the natural environment of an organism "selects for" traits that confer a reproductive advantage, causing evolutionary change, as Darwin described. This gives the appearance of purpose, but in natural selection there is no intentional choice. Artificial selection is purposive where natural selection is not, though biologists often use teleological language to describe it.


title: Natural selection

text: The peppered moth exists in both light and dark colours in Great Britain, but during the industrial revolution, many of the trees on which the moths rested became blackened by soot, giving the dark-coloured moths an advantage in hiding from predators. This gave dark-coloured moths a better chance of surviving to produce dark-coloured offspring, and in just fifty years from the first dark moth being caught, nearly all of the moths in industrial Manchester were dark. The balance was reversed by the effect of the Clean Air Act 1956, and the dark moths became rare again, demonstrating the influence of natural selection on peppered moth evolution. A recent study, using image analysis and avian vision models, shows that pale individuals more closely match lichen backgrounds than dark morphs and for the first time quantifies the camouflage of moths to predation risk.


title: Natural selection

text: The concept of fitness is central to natural selection. In broad terms, individuals that are more "fit" have better potential for survival, as in the well-known phrase "survival of the fittest", but the precise meaning of the term is much more subtle. Modern evolutionary theory defines fitness not by how long an organism lives, but by how successful it is at reproducing. If an organism lives half as long as others of its species, but has twice as many offspring surviving to adulthood, its genes become more common in the adult population of the next generation. Though natural selection acts on individuals, the effects of chance mean that fitness can only really be defined "on average" for the individuals within a population. The fitness of a particular genotype corresponds to the average effect on all individuals with that genotype.


title: Natural selection

text: A distinction must be made between the concept of "survival of the fittest" and "improvement in fitness". "Survival of the fittest" does not give an "improvement in fitness", it only represents the removal of the less fit variants from a population. A mathematical example of "survival of the fittest" is given by Haldane in his paper "The Cost of Natural Selection". Haldane called this process "substitution" or more commonly in biology, this is called "fixation". This is correctly described by the differential survival and reproduction of individuals due to differences in phenotype. On the other hand, "improvement in fitness" is not dependent on the differential survival and reproduction of individuals due to differences in phenotype, it is dependent on the absolute survival of the particular variant. The probability of a beneficial mutation occurring on some member of a population depends on the total number of replications of that variant. The mathematics of "improvement in fitness was described by Kleinman. An empirical example of "improvement in fitness" is given by the Kishony Mega-plate experiment. In this experiment, "improvement in fitness" depends on the number of replications of the particular variant for a new variant to appear that is capable of growing in the next higher drug concentration region. Fixation or substitution is not required for this "improvement in fitness". On the other hand, "improvement in fitness" can occur in an environment where "survival of the fittest" is also acting. Richard Lenski's classic "E. coli" long-term evolution experiment is an example of adaptation in a competitive environment, ("improvement in fitness" during "survival of the fittest"). The probability of a beneficial mutation occurring on some member of the lineage to give improved fitness is slowed by the competition. The variant which is a candidate for a beneficial mutation in this limited carrying capacity environment must first out-compete the "less fit" variants in order to accumulate the requisite number of replications for there to be a reasonable probability of that beneficial mutation occurring.


title: Natural selection

text: In biology, competition is an interaction between organisms in which the fitness of one is lowered by the presence of another. This may be because both rely on a limited supply of a resource such as food, water, or territory. Competition may be within or between species, and may be direct or indirect. Species less suited to compete should in theory either adapt or die out, since competition plays a powerful role in natural selection, but according to the "room to roam" theory it may be less important than expansion among larger clades.


title: Natural selection

text: Competition is modelled by "r/K" selection theory, which is based on Robert MacArthur and E. O. Wilson's work on island biogeography. In this theory, selective pressures drive evolution in one of two stereotyped directions: "r"- or "K"-selection. These terms, "r" and "K", can be illustrated in a of population dynamics:


title: Natural selection

text: where "r" is the growth rate of the population ("N"), and "K" is the carrying capacity of its local environmental setting. Typically, "r"-selected species exploit empty niches, and produce many offspring, each with a relatively low probability of surviving to adulthood. In contrast, "K"-selected species are strong competitors in crowded niches, and invest more heavily in much fewer offspring, each with a relatively high probability of surviving to adulthood.


title: Natural selection

text: Natural selection can act on any heritable phenotypic trait, and selective pressure can be produced by any aspect of the environment, including sexual selection and competition with members of the same or other species. However, this does not imply that natural selection is always directional and results in adaptive evolution; natural selection often results in the maintenance of the status quo by eliminating less fit variants.


title: Natural selection

text: Selection can be classified in several different ways, such as by its effect on a trait, on genetic diversity, by the life cycle stage where it acts, by the unit of selection, or by the resource being competed for.


title: Natural selection

text: Selection has different effects on traits. Stabilizing selection acts to hold a trait at a stable optimum, and in the simplest case all deviations from this optimum are selectively disadvantageous. Directional selection favours extreme values of a trait. The uncommon disruptive selection also acts during transition periods when the current mode is sub-optimal, but alters the trait in more than one direction. In particular, if the trait is quantitative and univariate then both higher and lower trait levels are favoured. Disruptive selection can be a precursor to speciation.


title: Natural selection

text: Alternatively, selection can be divided according to its effect on genetic diversity. Purifying or negative selection acts to remove genetic variation from the population (and is opposed by "de novo" mutation, which introduces new variation. In contrast, balancing selection acts to maintain genetic variation in a population, even in the absence of "de novo" mutation, by negative frequency-dependent selection. One mechanism for this is heterozygote advantage, where individuals with two different alleles have a selective advantage over individuals with just one allele. The polymorphism at the human ABO blood group locus has been explained in this way.


title: Natural selection

text: Another option is to classify selection by the life cycle stage at which it acts. Some biologists recognise just two types: viability (or survival) selection, which acts to increase an organism's probability of survival, and fecundity (or fertility or reproductive) selection, which acts to increase the rate of reproduction, given survival. Others split the life cycle into further components of selection. Thus viability and survival selection may be defined separately and respectively as acting to improve the probability of survival before and after reproductive age is reached, while fecundity selection may be split into additional sub-components including sexual selection, gametic selection, acting on gamete survival, and compatibility selection, acting on zygote formation.


title: Natural selection

text: Selection can also be classified by the level or unit of selection. Individual selection acts on the individual, in the sense that adaptations are "for" the benefit of the individual, and result from selection among individuals. Gene selection acts directly at the level of the gene. In kin selection and intragenomic conflict, gene-level selection provides a more apt explanation of the underlying process. Group selection, if it occurs, acts on groups of organisms, on the assumption that groups replicate and mutate in an analogous way to genes and individuals. There is an ongoing debate over the degree to which group selection occurs in nature.


title: Natural selection

text: Finally, selection can be classified according to the resource being competed for. Sexual selection results from competition for mates. Sexual selection typically proceeds via fecundity selection, sometimes at the expense of viability. Ecological selection is natural selection via any means other than sexual selection, such as kin selection, competition, and infanticide. Following Darwin, natural selection is sometimes defined as ecological selection, in which case sexual selection is considered a separate mechanism.


title: Natural selection

text: Sexual selection as first articulated by Darwin (using the example of the peacock's tail) refers specifically to competition for mates, which can be "intrasexual", between individuals of the same sex, that is male–male competition, or "intersexual", where one gender chooses mates, most often with males displaying and females choosing. However, in some species, mate choice is primarily by males, as in some fishes of the family Syngnathidae.


title: Natural selection

text: Phenotypic traits can be displayed in one sex and desired in the other sex, causing a positive feedback loop called a Fisherian runaway, for example, the extravagant plumage of some male birds such as the peacock. An alternate theory proposed by the same Ronald Fisher in 1930 is the sexy son hypothesis, that mothers want promiscuous sons to give them large numbers of grandchildren and so choose promiscuous fathers for their children. Aggression between members of the same sex is sometimes associated with very distinctive features, such as the antlers of stags, which are used in combat with other stags. More generally, intrasexual selection is often associated with sexual dimorphism, including differences in body size between males and females of a species.


title: Natural selection

text: Natural selection is seen in action in the development of antibiotic resistance in microorganisms. Since the discovery of penicillin in 1928, antibiotics have been used to fight bacterial diseases. The widespread misuse of antibiotics has selected for microbial resistance to antibiotics in clinical use, to the point that the methicillin-resistant "Staphylococcus aureus" (MRSA) has been described as a "superbug" because of the threat it poses to health and its relative invulnerability to existing drugs. Response strategies typically include the use of different, stronger antibiotics; however, new strains of MRSA have recently emerged that are resistant even to these drugs. This is an evolutionary arms race, in which bacteria develop strains less susceptible to antibiotics, while medical researchers attempt to develop new antibiotics that can kill them. A similar situation occurs with pesticide resistance in plants and insects. Arms races are not necessarily induced by man; a well-documented example involves the spread of a gene in the butterfly "Hypolimnas bolina" suppressing male-killing activity by "Wolbachia" bacteria parasites on the island of Samoa, where the spread of the gene is known to have occurred over a period of just five years


title: Natural selection

text: A prerequisite for natural selection to result in adaptive evolution, novel traits and speciation is the presence of heritable genetic variation that results in fitness differences. Genetic variation is the result of mutations, genetic recombinations and alterations in the karyotype (the number, shape, size and internal arrangement of the chromosomes). Any of these changes might have an effect that is highly advantageous or highly disadvantageous, but large effects are rare. In the past, most changes in the genetic material were considered neutral or close to neutral because they occurred in noncoding DNA or resulted in a synonymous substitution. However, many mutations in non-coding DNA have deleterious effects. Although both mutation rates and average fitness effects of mutations are dependent on the organism, a majority of mutations in humans are slightly deleterious.


title: Natural selection

text: Some mutations occur in "toolkit" or regulatory genes. Changes in these often have large effects on the phenotype of the individual because they regulate the function of many other genes. Most, but not all, mutations in regulatory genes result in non-viable embryos. Some nonlethal regulatory mutations occur in HOX genes in humans, which can result in a cervical rib or polydactyly, an increase in the number of fingers or toes. When such mutations result in a higher fitness, natural selection favours these phenotypes and the novel trait spreads in the population.


title: Natural selection

text: Established traits are not immutable; traits that have high fitness in one environmental context may be much less fit if environmental conditions change. In the absence of natural selection to preserve such a trait, it becomes more variable and deteriorate over time, possibly resulting in a vestigial manifestation of the trait, also called evolutionary baggage. In many circumstances, the apparently vestigial structure may retain a limited functionality, or may be co-opted for other advantageous traits in a phenomenon known as preadaptation. A famous example of a vestigial structure, the eye of the blind mole-rat, is believed to retain function in photoperiod perception.


title: Natural selection

text: Speciation requires a degree of reproductive isolation—that is, a reduction in gene flow. However, it is intrinsic to the concept of a species that hybrids are selected against, opposing the evolution of reproductive isolation, a problem that was recognised by Darwin. The problem does not occur in allopatric speciation with geographically separated populations, which can diverge with different sets of mutations. E. B. Poulton realized in 1903 that reproductive isolation could evolve through divergence, if each lineage acquired a different, incompatible allele of the same gene. Selection against the heterozygote would then directly create reproductive isolation, leading to the Bateson–Dobzhansky–Muller model, further elaborated by H. Allen Orr and Sergey Gavrilets. With reinforcement, however, natural selection can favor an increase in pre-zygotic isolation, influencing the process of speciation directly.


title: Natural selection

text: Natural selection acts on an organism's phenotype, or physical characteristics. Phenotype is determined by an organism's genetic make-up (genotype) and the environment in which the organism lives. When different organisms in a population possess different versions of a gene for a certain trait, each of these versions is known as an allele. It is this genetic variation that underlies differences in phenotype. An example is the ABO blood type antigens in humans, where three alleles govern the phenotype.


title: Natural selection

text: Some traits are governed by only a single gene, but most traits are influenced by the interactions of many genes. A variation in one of the many genes that contributes to a trait may have only a small effect on the phenotype; together, these genes can produce a continuum of possible phenotypic values.


title: Natural selection

text: When some component of a trait is heritable, selection alters the frequencies of the different alleles, or variants of the gene that produces the variants of the trait. Selection can be divided into three classes, on the basis of its effect on allele frequencies: directional, stabilizing, and disruptive selection. Directional selection occurs when an allele has a greater fitness than others, so that it increases in frequency, gaining an increasing share in the population. This process can continue until the allele is fixed and the entire population shares the fitter phenotype. Far more common is stabilizing selection, which lowers the frequency of alleles that have a deleterious effect on the phenotype—that is, produce organisms of lower fitness. This process can continue until the allele is eliminated from the population. Stabilizing selection conserves functional genetic features, such as protein-coding genes or regulatory sequences, over time by selective pressure against deleterious variants. Disruptive (or diversifying) selection is selection favoring extreme trait values over intermediate trait values. Disruptive selection may cause sympatric speciation through niche partitioning.


title: Natural selection

text: Some forms of balancing selection do not result in fixation, but maintain an allele at intermediate frequencies in a population. This can occur in diploid species (with pairs of chromosomes) when heterozygous individuals (with just one copy of the allele) have a higher fitness than homozygous individuals (with two copies). This is called heterozygote advantage or over-dominance, of which the best-known example is the resistance to malaria in humans heterozygous for sickle-cell anaemia. Maintenance of allelic variation can also occur through disruptive or diversifying selection, which favours genotypes that depart from the average in either direction (that is, the opposite of over-dominance), and can result in a bimodal distribution of trait values. Finally, balancing selection can occur through frequency-dependent selection, where the fitness of one particular phenotype depends on the distribution of other phenotypes in the population. The principles of game theory have been applied to understand the fitness distributions in these situations, particularly in the study of kin selection and the evolution of reciprocal altruism.


title: Natural selection

text: A portion of all genetic variation is functionally neutral, producing no phenotypic effect or significant difference in fitness. Motoo Kimura's neutral theory of molecular evolution by genetic drift proposes that this variation accounts for a large fraction of observed genetic diversity. Neutral events can radically reduce genetic variation through population bottlenecks. which among other things can cause the founder effect in initially small new populations. When genetic variation does not result in differences in fitness, selection cannot directly affect the frequency of such variation. As a result, the genetic variation at those sites is higher than at sites where variation does influence fitness. However, after a period with no new mutations, the genetic variation at these sites is eliminated due to genetic drift. Natural selection reduces genetic variation by eliminating maladapted individuals, and consequently the mutations that caused the maladaptation. At the same time, new mutations occur, resulting in a mutation–selection balance. The exact outcome of the two processes depends both on the rate at which new mutations occur and on the strength of the natural selection, which is a function of how unfavourable the mutation proves to be.


title: Natural selection

text: Genetic linkage occurs when the loci of two alleles are close on a chromosome. During the formation of gametes, recombination reshuffles the alleles. The chance that such a reshuffle occurs between two alleles is inversely related to the distance between them. Selective sweeps occur when an allele becomes more common in a population as a result of positive selection. As the prevalence of one allele increases, closely linked alleles can also become more common by "genetic hitchhiking", whether they are neutral or even slightly deleterious. A strong selective sweep results in a region of the genome where the positively selected haplotype (the allele and its neighbours) are in essence the only ones that exist in the population. Selective sweeps can be detected by measuring linkage disequilibrium, or whether a given haplotype is overrepresented in the population. Since a selective sweep also results in selection of neighbouring alleles, the presence of a block of strong linkage disequilibrium might indicate a 'recent' selective sweep near the centre of the block.


title: Natural selection

text: Background selection is the opposite of a selective sweep. If a specific site experiences strong and persistent purifying selection, linked variation tends to be weeded out along with it, producing a region in the genome of low overall variability. Because background selection is a result of deleterious new mutations, which can occur randomly in any haplotype, it does not produce clear blocks of linkage disequilibrium, although with low recombination it can still lead to slightly negative linkage disequilibrium overall.


title: Natural selection

text: Darwin's ideas, along with those of Adam Smith and Karl Marx, had a profound influence on 19th century thought, including his radical claim that "elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner" evolved from the simplest forms of life by a few simple principles. This inspired some of Darwin's most ardent supporters—and provoked the strongest opposition. Natural selection had the power, according to Stephen Jay Gould, to "dethrone some of the deepest and most traditional comforts of Western thought", such as the belief that humans have a special place in the world.


title: Natural selection

text: In the words of the philosopher Daniel Dennett, "Darwin's dangerous idea" of evolution by natural selection is a "universal acid," which cannot be kept restricted to any vessel or container, as it soon leaks out, working its way into ever-wider surroundings. Thus, in the last decades, the concept of natural selection has spread from evolutionary biology to other disciplines, including evolutionary computation, quantum Darwinism, evolutionary economics, evolutionary epistemology, evolutionary psychology, and cosmological natural selection. This unlimited applicability has been called universal Darwinism.


title: Natural selection

text: How life originated from inorganic matter remains an unresolved problem in biology. One prominent hypothesis is that life first appeared in the form of short self-replicating RNA polymers. On this view, life may have come into existence when RNA chains first experienced the basic conditions, as conceived by Charles Darwin, for natural selection to operate. These conditions are: heritability, variation of type, and competition for limited resources. The fitness of an early RNA replicator would likely have been a function of adaptive capacities that were intrinsic (i.e., determined by the nucleotide sequence) and the availability of resources. The three primary adaptive capacities could logically have been: (1) the capacity to replicate with moderate fidelity (giving rise to both heritability and variation of type), (2) the capacity to avoid decay, and (3) the capacity to acquire and process resources. These capacities would have been determined initially by the folded configurations (including those configurations with ribozyme activity) of the RNA replicators that, in turn, would have been encoded in their individual nucleotide sequences.


title: Natural selection

text: In 1881, the embryologist Wilhelm Roux published "Der Kampf der Theile im Organismus" ("The Struggle of Parts in the Organism") in which he suggested that the development of an organism results from a Darwinian competition between the parts of the embryo, occurring at all levels, from molecules to organs. In recent years, a modern version of this theory has been proposed by . According to this cellular Darwinism, random variation at the molecular level generates diversity in cell types whereas cell interactions impose a characteristic order on the developing embryo.


title: Natural selection

text: The social implications of the theory of evolution by natural selection also became the source of continuing controversy. Friedrich Engels, a German political philosopher and co-originator of the ideology of communism, wrote in 1872 that "Darwin did not know what a bitter satire he wrote on mankind, and especially on his countrymen, when he showed that free competition, the struggle for existence, which the economists celebrate as the highest historical achievement, is the normal state of the "animal kingdom"." Herbert Spencer and the eugenics advocate Francis Galton's interpretation of natural selection as necessarily progressive, leading to supposed advances in intelligence and civilisation, became a justification for colonialism, eugenics, and social Darwinism. For example, in 1940, Konrad Lorenz, in writings that he subsequently disowned, used the theory as a justification for policies of the Nazi state. He wrote "... selection for toughness, heroism, and social utility ... must be accomplished by some human institution, if mankind, in default of selective factors, is not to be ruined by domestication-induced degeneracy. The racial idea as the basis of our state has already accomplished much in this respect." Others have developed ideas that human societies and culture evolve by mechanisms analogous to those that apply to evolution of species.


title: Natural selection

text: More recently, work among anthropologists and psychologists has led to the development of sociobiology and later of evolutionary psychology, a field that attempts to explain features of human psychology in terms of adaptation to the ancestral environment. The most prominent example of evolutionary psychology, notably advanced in the early work of Noam Chomsky and later by Steven Pinker, is the hypothesis that the human brain has adapted to acquire the grammatical rules of natural language. Other aspects of human behaviour and social structures, from specific cultural norms such as incest avoidance to broader patterns such as gender roles, have been hypothesised to have similar origins as adaptations to the early environment in which modern humans evolved. By analogy to the action of natural selection on genes, the concept of memes—"units of cultural transmission," or culture's equivalents of genes undergoing selection and recombination—has arisen, first described in this form by Richard Dawkins in 1976 and subsequently expanded upon by philosophers such as Daniel Dennett as explanations for complex cultural activities, including human consciousness.


title: Natural selection

text: In 1922, Alfred J. Lotka proposed that natural selection might be understood as a physical principle that could be described in terms of the use of energy by a system, a concept later developed by Howard T. Odum as the maximum power principle in thermodynamics, whereby evolutionary systems with selective advantage maximise the rate of useful energy transformation.


title: Natural selection

text: The principles of natural selection have inspired a variety of computational techniques, such as "soft" artificial life, that simulate selective processes and can be highly efficient in 'adapting' entities to an environment defined by a specified fitness function. For example, a class of heuristic optimisation algorithms known as genetic algorithms, pioneered by John Henry Holland in the 1970s and expanded upon by David E. Goldberg, identify optimal solutions by simulated reproduction and mutation of a population of solutions defined by an initial probability distribution. Such algorithms are particularly useful when applied to problems whose energy landscape is very rough or has many local minima.


title: Natural selection

text: Darwinian evolution by natural selection is pervasive in literature, whether taken optimistically in terms of how humanity may evolve towards perfection, or pessimistically in terms of the dire consequences of the interaction of human nature and the struggle for survival. Among major responses is Samuel Butler's 1872 pessimistic "Erewhon" ("nowhere", written mostly backwards). In 1893 H. G. Wells imagined "The Man of the Year Million", transformed by natural selection into a being with a huge head and eyes, and shrunken body.


title: Courtney Stodden

text: Courtney Alexis Stodden (born August 29, 1994) is an American media personality, model, and singer. After competing in beauty pageants in their home state of Washington and releasing original music, then-16-year-old Stodden came to international attention after being wed to 51-year-old actor Doug Hutchison in 2011. The controversy and media attention surrounding the marriage led Stodden to appear in the reality television shows "Couples Therapy" (2012) and "Celebrity Big Brother" (2013), and later appearances on "Reality Ex-Wives" (2015), "The Mother/Daughter Experiment" (2016), "Celebs Go Dating" (2017), and "Courtney" (2020).


title: Courtney Stodden

text: Courtney Alexis Stodden was born on August 29, 1994, in Tacoma, Washington, to Alex John Stodden and Krista Kay Keller.


title: Courtney Stodden

text: They have two sisters, Ashley and Brittany, 9 and 11 years older than Stodden. Stodden describes their childhood as "beautiful and fun", stating that they were "extremely spoiled, in a good way." From a very young age, Stodden has stated that their passion was singing and writing their own music. They were raised in Ocean Shores, Washington.


title: Courtney Stodden

text: In 2017, Stodden said to "Radar Online" that they were bullied and abused over their mature looks from age 12 when they were in the sixth grade until their mother pulled them out of school at 16. Bullies had reportedly attacked them and fractured their left arm and they felt unsafe. They continued their education by being home schooled through an online private Christian academy.


title: Courtney Stodden

text: Stodden began in the entertainment industry as a youth by modeling. , Stodden's measurements were listed as 36-23-35 and in height. In 2009, Stodden hosted a cable TV show produced by North Beach Community TV in Ocean Shores, "The Courtney Stodden Show", which aired five times. In October 2009, Stodden competed as Miss Ocean Shores Teen USA in the 2010 Miss Washington Teen USA pageant (but did not win the title). In 2010, Stodden released the original songs "Car Candy", "Crazy", "Don't Put It on Me", "Hurting People", and "We Are America". "Star Observer" ranked "Don't Put It on Me" as number eleven on their list of The 11 Best Songs of '11. Stodden said, "'Don't Put It On Me' is a kind of tongue-in-cheek song that I didn't take seriously at all, but it obviously had a good message to it." Stodden's mother, Krista Keller, initially served as Stodden's manager, but Keller quit in the spring of 2015, citing "creative differences". During their marriage, Stodden was managed by Hutchison.


title: Courtney Stodden

text: In July 2012, Stodden and Hutchison were interviewed about their relationship on the Fox talk show "Father Albert", in an episode of ABC's "Good Morning America", and "E! News".


title: Courtney Stodden

text: The couple appeared as cast members in the second season of the VH1 reality television series "Couples Therapy", which premiered in October 2012. The series features publicly known couples receiving therapy for relationship problems. According to Stodden, the couple enrolled in therapy to resolve issues that arose from their big difference marriage in age. Despite criticism leveled at the couple, Dr. Jenn Berman, the marriage, family, and child therapist who worked with the couple during their appearance on the show, opined that she did not believe that Hutchison deliberately sought out young people, saying, "He's not a predator. He's not someone, who if Courtney left him, would be trolling the Internet or high schools for underage girls. That's not his m.o. This is not a guy who was seeking out teenagers. He was teaching a class, she wanted to be an actress, it was an acting class ... And that's how it started."


title: Courtney Stodden

text: Though Berman was eventually surprised by the dynamic between the two, she commented on her initial hesitations about working with the couple, saying, "I believe it was the wrong decision to let a 16-year-old marry a man in his 50s. It's uncomfortable to see... [at first] I said to my producer, 'I think this guy is a pedophile...I don't know if I can work with these people.' I don't condone it, but I do see that this is a married couple that is genuinely married and she has marital issues that needed to be worked on. I came in saying, 'She's a victim, he's a predator.' What I found out was that she has a lot more power in this relationship and he is far more powerless than I expected. His family has completely disowned him... He unfortunately has nothing besides her." Hutchison was also defended by Stodden's mother, Krista Keller, who praised Hutchison for the kindness with which he treats Stodden.


title: Courtney Stodden

text: In August 2013, Stodden became a housemate on the twelfth season of the British version of "Celebrity Big Brother" but was evicted on Day 21, two days before the season finale, after receiving the fewest votes to save against Carol McGiffin, Louie Spence, Mario Falcone and Vicky Entwistle.


title: Courtney Stodden

text: That October, Stodden appeared in a photo-op for PETA, which depicted them wearing a lettuce bikini to promote vegetarianism.


title: Courtney Stodden

text: On March 18, 2014, the video for 50 Cent's "Don't Worry Bout It" was released, featuring a cameo appearance by Stodden. That August, Stodden appeared in an episode of the Reelz reality television series "Hollywood Hillbillies".


title: Courtney Stodden

text: On May 14, 2015, Vivid Entertainment released a solo sex tape created by Stodden. Stodden stated that they would donate what they were paid to charity.


title: Courtney Stodden

text: On August 19, 2015, Rich Kid Mafia (RKM), a Los Angeles-based entertainment company whose primary services include artist management, digital marketing and music production, signed Stodden to an exclusive international management and development deal. Stodden appeared alongside their mother in the 2016 Lifetime series "". The same year, Stodden made their feature film debut in the independent film "Love Addict".


title: Courtney Stodden

text: In 2018, Stodden announced they were recording an extended play (EP) record, which they likened to "Lil Peep meets Lana Del Rey." In March 2018, discussing their separation from husband Hutchison, they admitted to often "playing a caricature" with the media, which they likened to the personas of Anna Nicole Smith and Marilyn Monroe: "I decided, at 23, that 'I'm not gonna play this anymore. I'm just going to be myself.'" They said. "I want to be honest [now], and potentially help people."


title: Courtney Stodden

text: In 2019, Stodden signed a deal with FNL Network to star in a self-titled reality show created by director Rocco Leo Gaglioti.


title: Courtney Stodden

text: In March 2020 Stodden finalized their divorce with Hutchinson. Stodden spent their time during the COVID-19 pandemic working on a memoir, recording a new album, starting a cosmetics line, and running an OnlyFans account.


title: Courtney Stodden

text: In May 2021, Stodden said that in 2011 television personality Chrissy Teigen tweeted and privately messaged them urging them to kill themselves. Teigen subsequently apologized to Stodden, saying she was sad and mortified at her past self, whom she described as "an insecure, attention seeking troll." Stodden accepted her apology but deemed it an attempt to save Teigen's business partnerships. A month later, Teigen released another apology in a lengthy blog post admitting to cyberbullying.


title: Courtney Stodden

text: Stodden is a vegetarian, explaining that they "never felt right eating animals before". Another reason for their vegetarianism was thought to be lactose intolerance, as Stodden explained in a "Couples Therapy" bonus clip. In 2014, it was further clarified that they were not lactose intolerant, and empathy for animals was the sole reason for their vegetarianism. Stodden had attempted to follow a vegan diet, but chose instead to follow a vegetarian diet due to fewer food restrictions. Stodden has promoted the vegetarian lifestyle on PETA's behalf.


title: Courtney Stodden

text: Stodden has said in interviews that they identify as a Christian. They commented: "I am a Christian girl. It may come as a surprise to some people that I support gay marriage. I believe wholeheartedly in 'Do not judge others.' Let people live their lives and be happy. That's what the bible teaches—love one another." Stodden has also said they are bisexual.


title: Courtney Stodden

text: In June 2013, Stodden had breast augmentation surgery to increase their breast size from a size C to a size DD. By March 2022, they had the implants removed, telling "Newsweek" that they did so due to back pain.


title: Courtney Stodden

text: In April 2021, Stodden publicly came out as non-binary and announced the decision to change their gender pronouns to they/them. They later updated their pronouns to she/they in June 2022.


title: Courtney Stodden

text: At age 16, Stodden signed up on the Internet for an acting workshop taught by actor Doug Hutchison, on the recommendation of a friend of their maternal aunt, who worked in Hollywood, and knew Hutchison. Hutchison, who was not aware that Stodden was a minor, began a courtship with them over the Internet that lasted between four and six months, during which they fell in love before having met in person. After Hutchison became aware of Stodden's age, he told their mother, Krista, who had monitored their online exchanges, and was aware of their relationship and their age difference, that he would cease his relationship with Stodden if their parents disapproved. Their parents, citing Stodden's "devout Christianity", allowed them to make their own decision.


title: Courtney Stodden

text: On May 20, 2011, Stodden married Hutchison in Las Vegas, Nevada. Stodden was his third wife. Their relationship drew controversy and criticism, as Stodden was 16 when they married 50-year-old Hutchison, who had been labeled a "pedophile" and "predator". It was also reported that Stodden's father was four years younger than his son-in-law Hutchison. According to Hutchison, as a result of his marriage to Stodden, his agent quit, his family disowned him and he received death threats.


title: Courtney Stodden

text: On November 1, 2013, the media reported that Stodden and Hutchison were ending their marriage of two and a half years. Stodden later told Fox News that their 34-year age gap was a primary contributing factor for their divorce. In August 2014, the couple announced that they had reconciled, with plans to renew their wedding vows later that year.


title: Courtney Stodden

text: It was announced on May 17, 2016, that Stodden and Hutchison were expecting their first child. In July, around three months into their pregnancy, Stodden announced they had suffered a miscarriage. On May 20, 2016, the pair celebrated their fifth anniversary by renewing their wedding vows.


title: Courtney Stodden

text: In January 2017, it was reported that Stodden and Hutchison had separated, but were still living together. In March 2018, Stodden filed for divorce and did not request spousal support. Their divorce was finalized in March 2020 as Stodden announced on their Instagram, with Stodden stating that they felt "absolutely taken advantage of" and "groomed", which they stated began when he reached out to them via email. Stodden made this accusation in a March 2022 interview, along with the statement that Hutchison was emotionally abusive and at times physically abusive, commenting, "I think that's the ultimate power a groomer has over a child. That emotional abuse and control." Hutchison, however, stated in a 2011 interview that Stodden contacted him via email first.


title: Stock exchange

text: A stock exchange, securities exchange, or bourse is an exchange where stockbrokers and traders can buy and sell securities, such as shares of stock, bonds and other financial instruments. Stock exchanges may also provide facilities for the issue and redemption of such securities and instruments and capital events including the payment of income and dividends. Securities traded on a stock exchange include stock issued by listed companies, unit trusts, derivatives, pooled investment products and bonds. Stock exchanges often function as "continuous auction" markets with buyers and sellers consummating transactions via open outcry at a central location such as the floor of the exchange or by using an electronic trading platform.


title: Stock exchange

text: To be able to trade a security on a certain stock exchange, the security must be listed there. Usually, there is a central location for record keeping, but trade is increasingly less linked to a physical place as modern markets use electronic communication networks, which give them advantages of increased speed and reduced cost of transactions. Trade on an exchange is restricted to brokers who are members of the exchange. In recent years, various other trading venues such as electronic communication networks, alternative trading systems and "dark pools" have taken much of the trading activity away from traditional stock exchanges.


title: Stock exchange

text: Initial public offerings of stocks and bonds to investors is done in the primary market and subsequent trading is done in the secondary market. A stock exchange is often the most important component of a stock market. Supply and demand in stock markets are driven by various factors that, as in all free markets, affect the price of stocks (see stock valuation).


title: Stock exchange

text: There is usually no obligation for stock to be issued through the stock exchange itself, nor must stock be subsequently traded on an exchange. Such trading may be "off exchange" or over-the-counter. This is the usual way that derivatives and bonds are traded. Increasingly, stock exchanges are part of a global securities market. Stock exchanges also serve an economic function in providing liquidity to shareholders in providing an efficient means of disposing of shares.


title: Stock exchange

text: In the 1300s, Venetian lenders would carry slates with information on the various issues for sale and meet with clients, much like a broker does today.


title: Stock exchange

text: The Real Merchants of Venice introduced the principle of exchanging debts between moneylenders; a lender looking to unload a high-risk, high-interest loan might exchange it for a different loan with another lender. These lenders also bought government debt issues.


title: Stock exchange

text: As the natural evolution of their business continued, the lenders began to sell debt issues to the first individual investors.2 The Venetians were the leaders in the field and the first to start trading securities from other governments.3


title: Stock exchange

text: There is little consensus among scholars as to when corporate stock was first traded. Some view the key event as the Dutch East India Company's founding in 1602, while others point to much earlier developments (Bruges, Antwerp in 1531 and in Lyon in 1548). The first book in history of securities exchange, the Confusion of Confusions, was written by the Dutch-Jewish trader Joseph de la Vega and the Amsterdam Stock Exchange is often considered the oldest “modern” securities market in the world. On the other hand, economist Ulrike Malmendier of the University of California at Berkeley argues that a share market existed as far back as ancient Rome, that derives from Etruscan "Argentari". In the Roman Republic, which existed for centuries before the Empire was founded, there were "societates publicanorum", organizations of contractors or leaseholders who performed temple-building and other services for the government. One such service was the feeding of geese on the Capitoline Hill as a reward to the birds after their honking warned of a Gallic invasion in 390 B.C. Participants in such organizations had "partes" or shares, a concept mentioned various times by the statesman and orator Cicero. In one speech, Cicero mentions "shares that had a very high price at the time". Such evidence, in Malmendier's view, suggests the instruments were tradable, with fluctuating values based on an organization's success. The "societas" declined into obscurity in the time of the emperors, as most of their services were taken over by direct agents of the state.


title: Stock exchange

text: Tradable bonds as a commonly used type of security were a more recent innovation, spearheaded by the Italian city-states of the late medieval and early Renaissance periods.


title: Stock exchange

text: Joseph de la Vega, also known as Joseph Penso de la Vega and by other variations of his name, was an Amsterdam trader from a Spanish Jewish family and a prolific writer as well as a successful businessman in 17th-century Amsterdam. His 1688 book "Confusion of Confusions" explained the workings of the city's stock market. It was the earliest book about stock trading and inner workings of a stock market, taking the form of a dialogue between a merchant, a shareholder and a philosopher, the book described a market that was sophisticated but also prone to excesses, and de la Vega offered advice to his readers on such topics as the unpredictability of market shifts and the importance of patience in investment.


title: Stock exchange

text: In England, King William III sought to modernize the kingdom's finances to pay for its wars, and thus the first government bonds were issued in 1693 and the Bank of England was set up the following year. Soon thereafter, English joint-stock companies began going public.


title: Stock exchange

text: London's first stockbrokers, however, were barred from the old commercial center known as the Royal Exchange, reportedly because of their rude manners. Instead, the new trade was conducted from coffee houses along Exchange Alley. By 1698, a broker named John Castaing, operating out of Jonathan's Coffee House, was posting regular lists of stock and commodity prices. Those lists mark the beginning of the London Stock Exchange.


title: Stock exchange

text: One of history's greatest financial bubbles occurred around 1720. At the center of it were the South Sea Company, set up in 1711 to conduct English trade with South America, and the Mississippi Company, focused on commerce with France's Louisiana colony and touted by transplanted Scottish financier John Law, who was acting in effect as France's central banker. Investors snapped up shares in both, and whatever else was available. In 1720, at the height of the mania, there was even an offering of "a company for carrying out an undertaking of great advantage, but nobody to know what it is".


title: Stock exchange

text: By the end of that same year, share prices had started collapsing, as it became clear that expectations of imminent wealth from the Americas were overblown. In London, Parliament passed the Bubble Act, which stated that only royally chartered companies could issue public shares. In Paris, Law was stripped of office and fled the country. Stock trading was more limited and subdued in subsequent decades. Yet the market survived, and by the 1790s shares were being traded in the young United States. On May 17, 1792, the New York Stock Exchange opened under a "Platanus occidentalis" (buttonwood tree) in New York City, as 24 stockbrokers signed the Buttonwood Agreement, agreeing to trade five securities under that buttonwood tree.


title: Stock exchange

text: Bombay Stock Exchange was started by Premchand Roychand in 1875. While BSE Limited is now synonymous with Dalal Street, it was not always so. In the 1850s, five stock brokers gathered together under a Banyan tree in front of Mumbai Town Hall, where Horniman Circle is now situated. A decade later, the brokers moved their location to another leafy setting, this time under banyan trees at the junction of Meadows Street and what was then called Esplanade Road, now Mahatma Gandhi Road. With a rapid increase in the number of brokers, they had to shift places repeatedly. At last, in 1874, the brokers found a permanent location, the one that they could call their own. The brokers group became an official organization known as "The Native Share & Stock Brokers Association" in 1875.


title: Stock exchange

text: The Bombay Stock Exchange continued to operate out of a building near the Town Hall until 1928. The present site near Horniman Circle was acquired by the exchange in 1928, and a building was constructed and occupied in 1930. The street on which the site is located came to be called "Dalal Street" in Hindi (meaning "Broker Street") due to the location of the exchange.


title: Stock exchange

text: On 31 August 1957, the BSE became the first stock exchange to be recognized by the Indian Government under the Securities Contracts Regulation Act. Construction of the present building, the Phiroze Jeejeebhoy Towers at Dalal Street, Fort area, began in the late 1970s and was completed and occupied by the BSE in 1980. Initially named the "BSE Towers", the name of the building was changed soon after occupation, in memory of Sir Phiroze Jamshedji Jeejeebhoy, chairman of the BSE since 1966, following his death.


title: Stock exchange

text: In 1986, the BSE developed the S&P BSE SENSEX index, giving the BSE a means to measure the overall performance of the exchange. In 2000, the BSE used this index to open its derivatives market, trading S&P BSE SENSEX futures contracts. The development of S&P BSE SENSEX options along with equity derivatives followed in 2001 and 2002, expanding the BSE's trading platform.


title: Stock exchange

text: Historically an open outcry floor trading exchange, the Bombay Stock Exchange switched to an electronic trading system developed by Cmc ltd. in 1995. It took the exchange only 50 days to make this transition. This automated, screen-based trading platform called BSE On-Line Trading (BOLT) had a capacity of 8 million orders per day. Now BSE has raised capital by issuing shares and as on 3 May 2017 the BSE share which is traded in NSE only closed with ₹999.


title: Stock exchange

text: Besides the borrowing capacity provided to an individual or firm by the banking system, in the form of credit or a loan, a stock exchange provides companies with the facility to raise capital for expansion through selling shares to the investing public.


title: Stock exchange

text: Capital intensive companies, particularly high tech companies, typically need to raise high volumes of capital in their early stages. For this reason, the public market provided by the stock exchanges has been one of the most important funding sources for many capital intensive startups. In the 1990s and early 2000s, hi-tech listed companies experienced a boom and bust in the world's major stock exchanges. Since then, it has been much more demanding for the high-tech entrepreneur to take his/her company public, unless either the company is already generating sales and earnings, or the company has demonstrated credibility and potential from successful outcomes: clinical trials, market research, patent registrations, etc. This is quite different from the situation of the 1990s to early-2000s period, when a number of companies (particularly Internet boom and biotechnology companies) went public in the most prominent stock exchanges around the world in the total absence of sales, earnings, or any type of well-documented promising outcome. Though it's not as common, it still happens that highly speculative and financially unpredictable hi-tech startups are listed for the first time in a major stock exchange. Additionally, there are smaller, specialized entry markets for these kind of companies with stock indexes tracking their performance (examples include the Alternext, CAC Small, SDAX, TecDAX).


title: Stock exchange

text: Companies have also raised significant amounts of capital through R&D limited partnerships. Tax law changes that were enacted in 1987 in the United States changed the tax deductibility of investments in R&D limited partnerships. In order for a partnership to be of interest to investors today, the cash on cash return must be high enough to entice investors.


title: Stock exchange

text: A general source of capital for startup companies has been venture capital. This source remains largely available today, but the maximum statistical amount that the venture company firms in aggregate will invest in any one company is not limitless (it was approximately $15 million in 2001 for a biotechnology company).


title: Stock exchange

text: Another alternative source of cash for a private company is a corporate partner, usually an established multinational company, which provides capital for the smaller company in return for marketing rights, patent rights, or equity. Corporate partnerships have been used successfully in a large number of cases.


title: Stock exchange

text: When people draw their savings and invest in shares (through an initial public offering or the seasoned equity offering of an already listed company), it usually leads to rational allocation of resources because funds, which could have been consumed, or kept in idle deposits with banks, are mobilized and redirected to help companies' management boards finance their organizations. This may promote business activity with benefits for several economic sectors such as agriculture, commerce and industry, resulting in stronger economic growth and higher productivity levels of firms.


title: Stock exchange

text: Companies view acquisitions as an opportunity to expand product lines, increase distribution channels, hedge against volatility, increase their market share, or acquire other necessary business assets. A takeover bid or mergers and acquisitions through the stock market is one of the simplest and most common ways for a company to grow by acquisition or fusion.


title: Stock exchange

text: Both casual and professional stock investors, as large as institutional investors or as small as an ordinary middle-class family, through dividends and stock price increases that may result in capital gains, share in the wealth of profitable businesses. Unprofitable and troubled businesses may result in capital losses for shareholders.


title: Stock exchange

text: By having a wide and varied scope of owners, companies generally tend to improve management standards and efficiency to satisfy the demands of these shareholders and the more stringent rules for public corporations imposed by public stock exchanges and the government. This improvement can be attributed in some cases to the price mechanism exerted through shares of stock, wherein the price of the stock falls when management is considered poor (making the firm vulnerable to a takeover by new management) or rises when management is doing well (making the firm less vulnerable to a takeover). In addition, publicly listed shares are subject to greater transparency so that investors can make informed decisions about a purchase. Consequently, it is alleged that public companies (companies that are owned by shareholders who are members of the general public and trade shares on public exchanges) tend to have better management records than privately held companies (those companies where shares are not publicly traded, often owned by the company founders, their families and heirs, or otherwise by a small group of investors).


title: Stock exchange

text: Despite this claim, some well-documented cases are known where it is alleged that there has been considerable slippage in corporate governance on the part of some public companies, particularly in the cases of accounting scandals. The policies that led to the dot-com bubble in the late 1990s and the subprime mortgage crisis in 2007–08 are also examples of corporate mismanagement. The mismanagement of companies such as Pets.com (2000), Enron (2001), One.Tel (2001), Sunbeam Products (2001), Webvan (2001), Adelphia Communications Corporation (2002), MCI WorldCom (2002), Parmalat (2003), American International Group (2008), Bear Stearns (2008), Lehman Brothers (2008), General Motors (2009) and Satyam Computer Services (2009) all received plenty of media attention.


title: Stock exchange

text: Many banks and companies worldwide utilize securities identification numbers (ISIN) to identify, uniquely, their stocks, bonds and other securities. Adding an ISIN code helps to distinctly identify securities and the ISIN system is used worldwide by funds, companies, and governments.


title: Stock exchange

text: However, when poor financial, ethical or managerial records become public, stock investors tend to lose money as the stock and the company tend to lose value. In the stock exchanges, shareholders of underperforming firms are often penalized by significant share price decline, and they tend as well to dismiss incompetent management teams.


title: Stock exchange

text: As opposed to other businesses that require huge capital outlay, investing in shares is open to both the large and small stock investors as minimum investment amounts are minimal. Therefore, the stock exchange provides the opportunity for small investors to own shares of the same companies as large investors.


title: Stock exchange

text: Governments at various levels may decide to borrow money to finance infrastructure projects such as sewage and water treatment works or housing estates by selling another category of securities known as bonds. These bonds can be raised through the stock exchange whereby members of the public buy them, thus loaning money to the government. The issuance of such bonds can obviate, in the short term, direct taxation of citizens to finance development—though by securing such bonds with the full faith and credit of the government instead of with collateral, the government must eventually tax citizens or otherwise raise additional funds to make any regular coupon payments and refund the principal when the bonds mature.


title: Stock exchange

text: At the stock exchange, share prices rise and decreases depending, largely, on economic forces. Share prices tend to rise or remain stable when companies and the economy in general show signs of stability and growth. A recession, depression, or financial crisis could eventually lead to a stock market crash. Therefore, the movement of share prices and in general of the stock indexes can be an indicator of the general trend in the economy.


title: Stock exchange

text: Each stock exchange imposes its own listing requirements upon companies that want to be listed on that exchange. Such conditions may include minimum number of shares outstanding, minimum market capitalization, and minimum annual income.


title: Stock exchange

text: Stock exchanges originated as mutual organizations, owned by its member stockbrokers. However, the major stock exchanges have "demutualized", where the members sell their shares in an initial public offering. In this way the mutual organization becomes a corporation, with shares that are listed on a stock exchange. Examples are Australian Securities Exchange (1998), Euronext (merged with New York Stock Exchange), NASDAQ (2002), Bursa Malaysia (2004), the New York Stock Exchange (2005), Bolsas y Mercados Españoles, and the São Paulo Stock Exchange (2007).


title: Stock exchange

text: The Shenzhen Stock Exchange and Shanghai Stock Exchange can be characterized as quasi-state institutions insofar as they were created by government bodies in China and their leading personnel are directly appointed by the China Securities Regulatory Commission.


title: Stock exchange

text: Another example is Tashkent Stock Exchange established in 1994, three years after the collapse of the Soviet Union, mainly state-owned but has a form of a public corporation (joint-stock company). Korea Exchange (KRX) owns 25% less one share of the Tashkent Stock Exchange.


title: Stock exchange

text: In 2018, there were 15 licensed stock exchanges in the United States, of which 13 actively traded securities. All of these exchanges were owned by three publicly traded multinational companies, Intercontinental Exchange, Nasdaq, Inc., and Cboe Global Markets, except one, IEX. In 2019, a group of financial corporations announced plans to open a members owned exchange, MEMX, an ownership structure similar to the mutual organizations of earlier exchanges.


title: Stock exchange

text: In the 19th century, exchanges were opened to trade forward contracts on commodities. Exchange traded forward contracts are called futures contracts. These "commodity markets" later started offering future contracts on other products, such as interest rates and shares, as well as options contracts. They are now generally known as futures exchanges.


title: Lipid

text: Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing energy, signaling, and acting as structural components of cell membranes. Lipids have applications in the cosmetic and food industries, and in nanotechnology.


title: Lipid

text: Lipids may be broadly defined as hydrophobic or amphiphilic small molecules; the amphiphilic nature of some lipids allows them to form structures such as vesicles, multilamellar/unilamellar liposomes, or membranes in an aqueous environment. Biological lipids originate entirely or in part from two distinct types of biochemical subunits or "building-blocks": ketoacyl and isoprene groups. Using this approach, lipids may be divided into eight categories: fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, saccharolipids, and polyketides (derived from condensation of ketoacyl subunits); and sterol lipids and prenol lipids (derived from condensation of isoprene subunits).


title: Lipid

text: Although the term "lipid" is sometimes used as a synonym for fats, fats are a subgroup of lipids called triglycerides. Lipids also encompass molecules such as fatty acids and their derivatives (including tri-, di-, monoglycerides, and phospholipids), as well as other sterol-containing metabolites such as cholesterol. Although humans and other mammals use various biosynthetic pathways both to break down and to synthesize lipids, some essential lipids can't be made this way and must be obtained from the diet.


title: Lipid

text: In 1815, Henri Braconnot classified lipids ("graisses") in two categories, "suifs" (solid greases or tallow) and "huiles" (fluid oils). In 1823, Michel Eugène Chevreul developed a more detailed classification, including oils, greases, tallow, waxes, resins, balsams and volatile oils (or essential oils).


title: Lipid

text: The first synthetic triglyceride was reported by Théophile-Jules Pelouze in 1844, when he produced tributyrin by treating butyric acid with glycerin in the presence of concentrated sulfuric acid. Several years later, Marcellin Berthelot, one of Pelouze's students, synthesized tristearin and tripalmitin by reaction of the analogous fatty acids with glycerin in the presence of gaseous hydrogen chloride at high temperature.


title: Lipid

text: In 1827, William Prout recognized fat ("oily" alimentary matters), along with protein ("albuminous") and carbohydrate ("saccharine"), as an important nutrient for humans and animals.