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Inbreeding

Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and other consequences that may arise from expression of deleterious recessive traits resulting from incestuous sexual relationships and consanguinity. Animals avoid inbreeding only rarely.

Inbreeding results in homozygosity, which can increase the chances of offspring being affected by recessive traits. In extreme cases, this usually leads to at least temporarily decreased biological fitness of a population (called inbreeding depression), which is its ability to survive and reproduce. An individual who inherits such deleterious traits is colloquially referred to as inbred. The avoidance of expression of such deleterious recessive alleles caused by inbreeding, via inbreeding avoidance mechanisms, is the main selective reason for outcrossing. Crossbreeding between populations sometimes has positive effects on fitness-related traits, but also sometimes leads to negative effects known as outbreeding depression. However, increased homozygosity increases the probability of fixing beneficial alleles and also slightly decreases the probability of fixing deleterious alleles in a population. Inbreeding can result in purging of deleterious alleles from a population through purifying selection.

Inbreeding is a technique used in selective breeding. For example, in livestock breeding, breeders may use inbreeding when trying to establish a new and desirable trait in the stock and for producing distinct families within a breed, but will need to watch for undesirable characteristics in offspring, which can then be eliminated through further selective breeding or culling. Inbreeding also helps to ascertain the type of gene action affecting a trait. Inbreeding is also used to reveal deleterious recessive alleles, which can then be eliminated through assortative breeding or through culling. In plant breeding, inbred lines are used as stocks for the creation of hybrid lines to make use of the effects of heterosis. Inbreeding in plants also occurs naturally in the form of self-pollination.

Inbreeding can significantly influence gene expression which can prevent inbreeding depression.

Overview
Offspring of biologically related persons are subject to the possible effects of inbreeding, such as congenital birth defects. The chances of such disorders are increased when the biological parents are more closely related. This is because such pairings have a 25% probability of producing homozygous zygotes, resulting in offspring with two recessive alleles, which can produce disorders when these alleles are deleterious. Because most recessive alleles are rare in populations, it is unlikely that two unrelated partners will both be carriers of the same deleterious allele; however, because close relatives share a large fraction of their alleles, the probability that any such deleterious allele is inherited from the common ancestor through both parents is increased dramatically. For each homozygous recessive individual formed there is an equal chance of producing a homozygous dominant individual — one completely devoid of the harmful allele. Contrary to common belief, inbreeding does not in itself alter allele frequencies, but rather increases the relative proportion of homozygotes to heterozygotes; however, because the increased proportion of deleterious homozygotes exposes the allele to natural selection, in the long run its frequency decreases more rapidly in inbred populations. In the short term, incestuous reproduction is expected to increase the number of spontaneous abortions of zygotes, perinatal deaths, and postnatal offspring with birth defects. The advantages of inbreeding may be the result of a tendency to preserve the structures of alleles interacting at different loci that have been adapted together by a common selective history.

Malformations or harmful traits can stay within a population due to a high homozygosity rate, and this will cause a population to become fixed for certain traits, like having too many bones in an area, like the vertebral column of wolves on Isle Royale or having cranial abnormalities, such as in Northern elephant seals, where their cranial bone length in the lower mandibular tooth row has changed. Having a high homozygosity rate is problematic for a population because it will unmask recessive deleterious alleles generated by mutations, reduce heterozygote advantage, and it is detrimental to the survival of small, endangered animal populations. When deleterious recessive alleles are unmasked due to the increased homozygosity generated by inbreeding, this can cause inbreeding depression.

There may also be other deleterious effects besides those caused by recessive diseases. Thus, similar immune systems may be more vulnerable to infectious diseases (see Major histocompatibility complex and sexual selection).

Inbreeding history of the population should also be considered when discussing the variation in the severity of inbreeding depression between and within species. With persistent inbreeding, there is evidence that shows that inbreeding depression becomes less severe. This is associated with the unmasking and elimination of severely deleterious recessive alleles. However, inbreeding depression is not a temporary phenomenon because this elimination of deleterious recessive alleles will never be complete. Eliminating slightly deleterious mutations through inbreeding under moderate selection is not as effective. Fixation of alleles most likely occurs through Muller's ratchet, when an asexual population's genome accumulates deleterious mutations that are irreversible.

Despite all its disadvantages, inbreeding can also have a variety of advantages, such as ensuring a child produced from the mating contains, and will pass on, a higher percentage of its mother/father's genetics, reducing the recombination load, and allowing the expression of recessive advantageous phenotypes. Some species with a Haplodiploidy mating system depend on the ability to produce sons to mate with as a means of ensuring a mate can be found if no other male is available. It has been proposed that under circumstances when the advantages of inbreeding outweigh the disadvantages, preferential breeding within small groups could be promoted, potentially leading to speciation.

Genetic disorders
Autosomal recessive disorders occur in individuals who have two copies of an allele for a particular recessive genetic mutation. Except in certain rare circumstances, such as new mutations or uniparental disomy, both parents of an individual with such a disorder will be carriers of the gene. These carriers do not display any signs of the mutation and may be unaware that they carry the mutated gene. Since relatives share a higher proportion of their genes than do unrelated people, it is more likely that related parents will both be carriers of the same recessive allele, and therefore their children are at a higher risk of inheriting an autosomal recessive genetic disorder. The extent to which the risk increases depends on the degree of genetic relationship between the parents; the risk is greater when the parents are close relatives and lower for relationships between more distant relatives, such as second cousins, though still greater than for the general population.

Children of parent-child or sibling-sibling unions are at an increased risk compared to cousin-cousin unions. Inbreeding may result in a greater than expected phenotypic expression of deleterious recessive alleles within a population. As a result, first-generation inbred individuals are more likely to show physical and health defects, including: • Lower intelligence quotient levels and higher incidence rates of being affected by an intellectual disability

• Reduced fertility both in litter size and sperm viability

• Increased genetic disorders

• Fluctuating facial asymmetry

• Lower birth rate

• Higher infant mortality and child mortality

• Smaller adult size

• Loss of immune system function

• Increased cardiovascular risks The isolation of a small population for a period of time can lead to inbreeding within that population, resulting in increased genetic relatedness between breeding individuals. Inbreeding depression can also occur in a large population if individuals tend to mate with their relatives, instead of mating randomly.

Due to higher prenatal and postnatal mortality rates, some individuals in the first generation of inbreeding will not live on to reproduce. Over time, with isolation, such as a population bottleneck caused by purposeful (assortative) breeding or natural environmental factors, the deleterious inherited traits are culled.

Island species are often very inbred, as their isolation from the larger group on a mainland allows natural selection to work on their population. This type of isolation may result in the formation of race or even speciation, as the inbreeding first removes many deleterious genes, and permits the expression of genes that allow a population to adapt to an ecosystem. As the adaptation becomes more pronounced, the new species or race radiates from its entrance into the new space, or dies out if it cannot adapt and, most importantly, reproduce.

The reduced genetic diversity, for example due to a bottleneck will unavoidably increase inbreeding for the entire population. This may mean that a species may not be able to adapt to changes in environmental conditions. Each individual will have similar immune systems, as immune systems are genetically based. When a species becomes endangered, the population may fall below a minimum whereby the forced interbreeding between the remaining animals will result in extinction.

Natural breedings include inbreeding by necessity, and most animals only migrate when necessary. In many cases, the closest available mate is a mother, sister, grandmother, father, brother, or grandfather. In all cases, the environment presents stresses to remove from the population those individuals who cannot survive because of illness.

There was an assumption that wild populations do not inbreed; this is not what is observed in some cases in the wild. However, in species such as horses, animals in wild or feral conditions often drive off the young of both sexes, thought to be a mechanism by which the species instinctively avoids some of the genetic consequences of inbreeding. In general, many mammal species, including humanity's closest primate relatives, avoid close inbreeding possibly due to the deleterious effects.

Examples
Although there are several examples of inbred populations of wild animals, the negative consequences of this inbreeding are poorly documented. In the South American sea lion, there was concern that recent population crashes would reduce genetic diversity. Historical analysis indicated that a population expansion from just two matrilineal lines was responsible for most of the individuals within the population. Even so, the diversity within the lines allowed great variation in the gene pool that may help to protect the South American sea lion from extinction. In lions, prides are often followed by related males in bachelor groups. When the dominant male is killed or driven off by one of these bachelors, a father may be replaced by his son. There is no mechanism for preventing inbreeding or to ensure outcrossing. In the prides, most lionesses are related to one another. If there is more than one dominant male, the group of alpha males are usually related. Two lines are then being "line bred". Also, in some populations, such as the Crater lions, it is known that a population bottleneck has occurred. Researchers found far greater genetic heterozygosity than expected. In fact, predators are known for low genetic variance, along with most of the top portion of the trophic levels of an ecosystem. Additionally, the alpha males of two neighboring prides can be from the same litter; one brother may come to acquire leadership over another's pride, and subsequently mate with his 'nieces' or cousins. However, killing another male's cubs, upon the takeover, allows the new selected gene complement of the incoming alpha male to prevail over the previous male. There are genetic assays being scheduled for lions to determine their genetic diversity. The preliminary studies show results inconsistent with the outcrossing paradigm based on individual environments of the studied groups.

In Central California, sea otters were thought to have been driven to extinction due to over hunting, until a small colony was discovered in the Point Sur region in the 1930s. Since then, the population has grown and spread along the central Californian coast to around 2,000 individuals, a level that has remained stable for over a decade. Population growth is limited by the fact that all Californian sea otters are descended from the isolated colony, resulting in inbreeding.

Cheetahs are another example of inbreeding. Thousands of years ago, the cheetah went through a population bottleneck that reduced its population dramatically so the animals that are alive today are all related to one another. A consequence from inbreeding for this species has been high juvenile mortality, low fecundity, and poor breeding success.

In a study on an island population of song sparrows, individuals that were inbred showed significantly lower survival rates than outbred individuals during a severe winter weather related population crash. These studies show that inbreeding depression and ecological factors have an influence on survival.

The Florida panther population was reduced to about 30 animals, so inbreeding became a problem. Several females were imported from Texas and now the population is better off genetically.

Measures
A measure of inbreeding of an individual A is the probability F(A) that both alleles in one locus are derived from the same allele in an ancestor. These two identical alleles that are both derived from a common ancestor are said to be identical by descent. This probability F(A) is called the "coefficient of inbreeding".

Another useful measure that describes the extent to which two individuals are related (say individuals A and B) is their coancestry coefficient f(A,B), which gives the probability that one randomly selected allele from A and another randomly selected allele from B are identical by descent. This is also denoted as the kinship coefficient between A and B.

A particular case is the self-coancestry of individual A with itself, f(A,A), which is the probability that taking one random allele from A and then, independently and with replacement, another random allele also from A, both are identical by descent. Since they can be identical by descent by sampling the same allele or by sampling both alleles that happen to be identical by descent, we have f(A,A) = 1/2 + F(A)/2.

Both the inbreeding and the coancestry coefficients can be defined for specific individuals or as average population values. They can be computed from genealogies or estimated from the population size and its breeding properties, but all methods assume no selection and are limited to neutral alleles.

There are several methods to compute this percentage. The two main ways are the path method and the tabular method.

Typical coancestries between relatives are as follows:
 * Father/daughter or mother/son → 25% ($1/4$)
 * Brother/sister → 25% ($1/4$)
 * Grandfather/granddaughter or grandmother/grandson → 12.5% ($1/8$)
 * Half-brother/half-sister, Double cousins → 12.5% ($1/8$)
 * Uncle/niece or aunt/nephew → 12.5% ($1/8$)
 * Great-grandfather/great-granddaughter or great-grandmother/great-grandson → 6.25% ($1/16$)
 * Half-uncle/niece or half-aunt/nephew → 6.25% ($1/16$)
 * First cousins → 6.25% ($1/16$)

Wild animals

 * Banded mongoose females regularly mate with their fathers and brothers.
 * Bed bugs: North Carolina State University found that bedbugs, in contrast to most other insects, tolerate incest and are able to genetically withstand the effects of inbreeding quite well.
 * Common fruit fly females prefer to mate with their own brothers over unrelated males.
 * Cottony cushion scales: 'It turns out that females in these hermaphrodite insects are not really fertilizing their eggs themselves, but instead are having this done by a parasitic tissue that infects them at birth,' says Laura Ross of Oxford University's Department of Zoology. 'It seems that this infectious tissue derives from left-over sperm from their father, who has found a sneaky way of having more children by mating with his daughters.'
 * Adactylidium: The single male offspring mite mates with all the daughters when they are still in the mother. The females, now impregnated, cut holes in their mother's body so that they can emerge. The male emerges as well, but does not look for food or new mates, and dies after a few hours. The females die at the age of 4 days, when their own offspring eat them alive from the inside.

Domestic animals

Breeding in domestic animals is primarily assortative breeding (see selective breeding). Without the sorting of individuals by trait, a breed could not be established, nor could poor genetic material be removed. Homozygosity is the case where similar or identical alleles combine to express a trait that is not otherwise expressed (recessiveness). Inbreeding exposes recessive alleles through increasing homozygosity.

Breeders must avoid breeding from individuals that demonstrate either homozygosity or heterozygosity for disease causing alleles. The goal of preventing the transfer of deleterious alleles may be achieved by reproductive isolation, sterilization, or, in the extreme case, culling. Culling is not strictly necessary if genetics are the only issue in hand. Small animals such as cats and dogs may be sterilized, but in the case of large agricultural animals, such as cattle, culling is usually the only economic option.

The issue of casual breeders who inbreed irresponsibly is discussed in the following quotation on cattle: Meanwhile, milk production per cow per lactation increased from 17,444 lbs to 25,013 lbs from 1978 to 1998 for the Holstein breed. Mean breeding values for milk of Holstein cows increased by 4,829 lbs during this period. High producing cows are increasingly difficult to breed and are subject to higher health costs than cows of lower genetic merit for production (Cassell, 2001).

Intensive selection for higher yield has increased relationships among animals within breed and increased the rate of casual inbreeding. Many of the traits that affect profitability in crosses of modern dairy breeds have not been studied in designed experiments. Indeed, all crossbreeding research involving North American breeds and strains is very dated (McAllister, 2001) if it exists at all.

The BBC produced two documentaries on dog inbreeding titled Pedigree Dogs Exposed and Pedigree Dogs Exposed: Three Years On that document the negative health consequences of excessive inbreeding.

Linebreeding
Linebreeding is a form of inbreeding. There is no clear distinction between the two terms, but linebreeding may encompass crosses between individuals and their descendants or two cousins. This method can be used to increase a particular animal's contribution to the population. While linebreeding is less likely to cause problems in the first generation than does inbreeding, over time, linebreeding can reduce the genetic diversity of a population and cause problems related to a too-small gene pool that may include an increased prevalence of genetic disorders and inbreeding depression.

Outcrossing
Outcrossing is where two unrelated individuals are crossed to produce progeny. In outcrossing, unless there is verifiable genetic information, one may find that all individuals are distantly related to an ancient progenitor. If the trait carries throughout a population, all individuals can have this trait. This is called the founder effect. In the well established breeds, that are commonly bred, a large gene pool is present. For example, in 2004, over 18,000 Persian cats were registered. A possibility exists for a complete outcross, if no barriers exist between the individuals to breed. However, it is not always the case, and a form of distant linebreeding occurs. Again it is up to the assortative breeder to know what sort of traits, both positive and negative, exist within the diversity of one breeding. This diversity of genetic expression, within even close relatives, increases the variability and diversity of viable stock.

Laboratory animals
Systematic inbreeding and maintenance of inbred strains of laboratory mice and rats is of great importance for biomedical research. The inbreeding guarantees a consistent and uniform animal model for experimental purposes and enables genetic studies in congenic and knock-out animals. In order to achieve a mouse strain that is considered inbred, a minimum of 20 sequential generations of sibling matings must occur. With each successive generation of breeding, homozygosity in the entire genome increases, eliminating heterozygous loci. With 20 generations of sibling matings, homozygosity is occurring at roughly 98.7% of all loci in the genome, allowing for these offspring to serve as animal models for genetic studies. The use of inbred strains is also important for genetic studies in animal models, for example to distinguish genetic from environmental effects. The mice that are inbred typically show considerably lower survival rates.

Effects
Inbreeding increases homozygosity, which can increase the chances of the expression of deleterious or beneficial recessive alleles and therefore has the potential to either decrease or increase the fitness of the offspring. Depending on the rate of inbreeding, natural selection may still be able to eliminate deleterious alleles. With continuous inbreeding, genetic variation is lost and homozygosity is increased, enabling the expression of recessive deleterious alleles in homozygotes. The coefficient of inbreeding, or the degree of inbreeding in an individual, is an estimate of the percent of homozygous alleles in the overall genome. The more biologically related the parents are, the greater the coefficient of inbreeding, since their genomes have many similarities already. This overall homozygosity becomes an issue when there are deleterious recessive alleles in the gene pool of the family. By pairing chromosomes of similar genomes, the chance for these recessive alleles to pair and become homozygous greatly increases, leading to offspring with autosomal recessive disorders. However, these deleterious effects are common for very close relatives but not for those related on the 3rd cousin or greater level, who exhibit increased fitness.

Inbreeding is especially problematic in small populations where the genetic variation is already limited. By inbreeding, individuals are further decreasing genetic variation by increasing homozygosity in the genomes of their offspring. Thus, the likelihood of deleterious recessive alleles to pair is significantly higher in a small inbreeding population than in a larger inbreeding population.

The fitness consequences of consanguineous mating have been studied since their scientific recognition by Charles Darwin in 1839. Some of the most harmful effects known from such breeding includes its effects on the mortality rate as well as on the general health of the offspring. Since the 1960s, there have been many studies to support such debilitating effects on the human organism. Specifically, inbreeding has been found to decrease fertility as a direct result of increasing homozygosity of deleterious recessive alleles. Fetuses produced by inbreeding also face a greater risk of spontaneous abortions due to inherent complications in development. Among mothers who experience stillbirths and early infant deaths, those that are inbreeding have a significantly higher chance of reaching repeated results with future offspring. Additionally, consanguineous parents possess a high risk of premature birth and producing underweight and undersized infants. Viable inbred offspring are also likely to be inflicted with physical deformities and genetically inherited diseases. Studies have confirmed an increase in several genetic disorders due to inbreeding such as blindness, hearing loss, neonatal diabetes, limb malformations, disorders of sex development, schizophrenia and several others. Moreover, there is an increased risk for congenital heart disease depending on the inbreeding coefficient (See coefficient of inbreeding) of the offspring, with significant risk accompanied by an F =.125 or higher.

Prevalence
The general negative outlook and eschewal of inbreeding that is prevalent in the Western world today has roots from over 2000 years ago. Specifically, written documents such as the Bible illustrate that there have been laws and social customs that have called for the abstention from inbreeding. Along with cultural taboos, parental education and awareness of inbreeding consequences have played large roles in minimizing inbreeding frequencies in areas like Europe. That being so, there are less urbanized and less populated regions across the world that have shown continuity in the practice of inbreeding.

The continuity of inbreeding is often either by choice or unavoidably due to the limitations of the geographical area. When by choice, the rate of consanguinity is highly dependent on religion and culture. In the Western world some Anabaptist groups are highly inbred because they originate from small founder populations and until today marriage outside the groups is not allowed for members. Especially the Reidenbach Old Order Mennonites and the Hutterites stem from very small founder populations. The same is true for some Hasidic and Haredi Jewish groups.

Of the practicing regions, Middle Eastern and northern Africa territories show the greatest frequencies of consanguinity.

Among these populations with high levels of inbreeding, researchers have found several disorders prevalent among inbred offspring. In Lebanon, Saudi Arabia, Egypt, and in Israel, the offspring of consanguineous relationships have an increased risk of congenital malformations, congenital heart defects, congenital hydrocephalus and neural tube defects. Furthermore, among inbred children in Palestine and Lebanon, there is a positive association between consanguinity and reported cleft lip/palate cases. Historically, populations of Qatar have engaged in consanguineous relationships of all kinds, leading to high risk of inheriting genetic diseases. As of 2014, around 5% of the Qatari population suffered from hereditary hearing loss; most were descendants of a consanguineous relationship.

Royalty and nobility
Inter-nobility marriage was used as a method of forming political alliances among elites. These ties were often sealed only upon the birth of progeny within the arranged marriage. Thus marriage was seen as a union of lines of nobility and not as a contract between individuals.

Royal intermarriage was often practiced among European royal families, usually for interests of state. Over time, due to the relatively limited number of potential consorts, the gene pool of many ruling families grew progressively smaller, until all European royalty was related. This also resulted in many being descended from a certain person through many lines of descent, such as the numerous European royalty and nobility descended from the British Queen Victoria or King Christian IX of Denmark. The House of Habsburg was known for its intermarriages; the Habsburg lip often cited as an ill-effect. The closely related houses of Habsburg, Bourbon, Braganza and Wittelsbach also frequently engaged in first-cousin unions as well as the occasional double-cousin and uncle–niece marriages.

In ancient Egypt, royal women were believed to carry the bloodlines and so it was advantageous for a pharaoh to marry his sister or half-sister; in such cases a special combination between endogamy and polygamy is found. Normally, the old ruler's eldest son and daughter (who could be either siblings or half-siblings) became the new rulers. All rulers of the Ptolemaic dynasty uninterruptedly from Ptolemy IV (Ptolemy II married his sister but had no issue) were married to their brothers and sisters, so as to keep the Ptolemaic blood "pure" and to strengthen the line of succession. King Tutankhamun's mother is reported to have been the half-sister to his father, Cleopatra VII (also called Cleopatra VI) and Ptolemy XIII, who married and became co-rulers of ancient Egypt following their father's death, are the most widely known example.

title: Inbreeding


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Incest taboo

An incest taboo  is any cultural rule or norm that prohibits sexual relations between certain members of the same family, mainly between individuals related by blood. All known human cultures have norms that exclude certain close relatives from those considered suitable or permissible sexual or marriage partners, making such relationships taboo. However, different norms exist among cultures as to which blood relations are permissible as sexual partners and which are not. Sexual relations between related persons which are subject to the taboo are called incestuous relationships.

Some cultures proscribe sexual relations between clan-members, even when no traceable biological relationship exists, while members of other clans are permissible irrespective of the existence of a biological relationship. In many cultures, certain types of cousin relations are preferred as sexual and marital partners, whereas in others these are taboo. Some cultures permit sexual and marital relations between aunts/uncles and nephews/nieces. In some instances, brother–sister marriages have been practised by the elites with some regularity. Parent–child and sibling–sibling unions are almost universally taboo.

Origin
Debate about the origin of the incest taboo has often been framed as a question of whether it is based in nature or nurture.

One explanation sees the incest taboo as a cultural implementation of a biologically evolved preference for sexual partners with whom one is unlikely to share genes, since inbreeding may have detrimental outcomes. The most widely held hypothesis proposes that the so-called Westermarck effect discourages adults from engaging in sexual relations with individuals with whom they grew up. The existence of the Westermarck effect has achieved some empirical support.

Another school argues that the incest prohibition is a cultural construct which arises as a side effect of a general human preference for group exogamy, which arises because intermarriage between groups construct valuable alliances that improve the ability for both groups to thrive. According to this view, the incest taboo is not necessarily universal, but is likely to arise and become more strict under cultural circumstances that favour exogamy over endogamy, and likely to become more lax under circumstances that favor endogamy. This hypothesis has also achieved some empirical support.

Limits to biological evolution of taboo
While it is theoretically possible that natural selection may, under certain genetic circumstances, select for individuals that instinctively avoid mating with (close) relatives, incest will still exist in the gene pool because even genetically weakened, inbred individuals are better watchposts against predators than none at all, and weak individuals are useful for the stronger individuals in the group as looking out for predators without being able to seriously compete with the stronger individuals. Additionally, protecting the health of closer relatives and their inbred offspring is more evolutionarily advantageous than punishing said relative, especially in a context where predation and starvation are significant factors, as opposed to a rich welfare state.

Research
Modern anthropology developed at a time when a great many human societies were illiterate, and much of the research on incest taboos has taken place in societies without legal codes, and, therefore, without written laws concerning marriage and incest. Nevertheless, anthropologists have found that the institution of marriage, and rules concerning appropriate and inappropriate sexual behavior, exist in every society. The following excerpt from Notes and Queries on Anthropology (1951), a well-established field manual for ethnographic research, illustrates the scope of ethnographic investigation into the matter:

"Incest is sexual intercourse between individuals related in certain prohibited degrees of kinship. In every society there are rules prohibiting incestuous unions, both as to sexual intercourse and recognized marriage. The two prohibitions do not necessarily coincide. There is no uniformity as to which degrees are involved in the prohibitions. The rules regulating incest must be investigated in every society by means of the genealogical method. The prohibition may be so narrow as to include only one type of parent–child relationship (though this is very rare), or those within the elementary family; or so wide as to include all with whom genealogical or classificatory kinship can be traced. The more usual practice is that unions with certain relatives only are considered incestuous, the relationships being regulated by the type of descent emphasized. In some societies unions with certain persons related by affinity are also considered incestuous.

What penalties fall on (a) the individuals concerned; (b) the community as a whole? Are such penalties enforced by authority, or are they believed to ensure automatically by all action of supernatural force? Is there any correlation between the severity of the penalty and the nearness of the blood-tie of the partners in guilt? Should children be born as the result of incestuous unions, how are they treated? Are there any methods, ritual or legal, by which persons who fall within the prohibited degrees and wish to marry can break the relationship and become free to marry?"

It should be further noted that in these theories anthropologists are generally concerned solely with brother–sister incest, and are not claiming that all sexual relations among family members are taboo or even necessarily considered incestuous by that society. These theories are further complicated by the fact that in many societies people related to one another in different ways, and sometimes distantly, are classified together as siblings, and others who are just as closely related genetically are not considered family members.

Moreover, the definition restricts itself to sexual intercourse; this does not mean that other forms of sexual contact do not occur, or are proscribed, or prescribed. For example, in some Inuit societies in the Arctic, and traditionally in Bali, mothers would routinely stroke the penises of their infant sons; such behavior was considered no more sexual than breast-feeding.

It should also be noted that, in these theories, anthropologists are primarily concerned with marriage rules and not actual sexual behavior. In short, anthropologists were not studying "incest" per se; they were asking informants what they meant by "incest", and what the consequences of "incest" were, in order to map out social relationships within the community.

This excerpt also suggests that the relationship between sexual and marriage practices is complex, and that societies distinguish between different sorts of prohibitions. In other words, although an individual may be prohibited from marrying or having sexual relations with many people, different sexual relations may be prohibited for different reasons, and with different penalties.

For example, Trobriand Islanders prohibit both sexual relations between a woman and her brother, and between a woman and her father, but they describe these prohibitions in very different ways: relations between a woman and her brother fall within the category of forbidden relations among members of the same clan; relations between a woman and her father do not. This is because the Trobrianders are matrilineal; children belong to the clan of their mother and not of their father. Thus, sexual relations between a man and his mother's sister (and mother's sister's daughter) are also considered incestuous, but relations between a man and his father's sister are not. A man and his father's sister will often have a flirtatious relationship, and, far from being taboo, Trobriand society encourages a man and his father's sister or the daughter of his father's sister to have sexual relations or marry.

Instinctual and genetic explanations
An explanation for the taboo is that it is due to an instinctual, inborn aversion that would lower the adverse genetic effects of inbreeding such as a higher incidence of congenital birth defects (see article Inbreeding depression). Since the rise of modern genetics, belief in this theory has grown.

Birth defects and inbreeding
The increase in frequency of birth defects often attributed to inbreeding results directly from an increase in the frequency of homozygous alleles inherited by the offspring of inbred couples. This leads to an increase in homozygous allele frequency within a population, and results in diverging effects. Should a child inherit the version of homozygous alleles responsible for a birth defect from its parents, the birth defect will be expressed; on the other hand, should the child inherit the version of homozygous alleles not responsible for a birth defect, it would actually decrease the ratio of the allele version responsible for the birth defect in that population. The overall consequences of these diverging effects depends in part on the size of the population.

In small populations, as long as children born with inheritable birth defects die (or are killed) before they reproduce, the ultimate effect of inbreeding will be to decrease the frequency of defective genes in the population; over time, the gene pool will be healthier. However, in larger populations, it is more likely that large numbers of carriers will survive and mate, leading to more constant rates of birth defects. Besides recessive genes, there are also other reasons why inbreeding may be harmful, such as a narrow range of certain immune systems genes in a population increasing vulnerability to infectious diseases (see Major histocompatibility complex and sexual selection). The biological costs of incest also depend largely on the degree of genetic proximity between the two relatives engaging in incest. This fact may explain why the cultural taboo generally includes prohibitions against sex between close relatives but less often includes prohibitions against sex between more distal relatives. Children born of close relatives have decreased survival. Many mammal species, including humanity's closest primate relatives, avoid incest.

Westermarck effect
The Westermarck effect, first proposed by Edvard Westermarck in 1891, is the theory that children reared together, regardless of biological relationship, form a sentimental attachment that is by its nature non-erotic. Melford Spiro argued that his observations that unrelated children reared together on Israeli Kibbutzim nevertheless avoided one another as sexual partners confirmed the Westermarck effect. Joseph Shepher in a study examined the second generation in a kibbutz and found no marriages and no sexual activity between the adolescents in the same peer group. This was not enforced but voluntary. Looking at the second generation adults in all kibbutzim, out of a total of 2769 marriages, none were between those of the same peer group.

However, according to a book review by John Hartung of a book by Shepher, out of 2516 marriages documented in Israel, 200 were between couples reared in the same kibbutz. These marriages occurred after young adults reared on kibbutzim had served in the military and encountered tens of thousands of other potential mates, and 200 marriages is higher than what would be expected by chance. Of these 200 marriages, five were between men and women who had been reared together for the first six years of their lives, which would argue against the Westermarck effect.

A study in Taiwan of marriages where the future bride is adopted in the groom's family as an infant or small child found that these marriages have higher infidelity and divorce and lower fertility than ordinary marriages; it has been argued that this observation is consistent with the Westermarck effect.

Third-parties' objections
Another approach is looking at moral objections to third-party incest. This increases the longer a child has grown up together with another child of the opposite sex. This occurs even if the other child is genetically unrelated. Humans have been argued to have a special kin detection system that besides the incest taboo also regulates a tendency towards altruism towards kin.

Counter arguments
One objection against an instinctive and genetic basis for the incest taboo is that incest does occur. Anthropologists have also argued that the social construct "incest" (and the incest taboo) is not the same thing as the biological phenomenon of "inbreeding". For example, there is equal genetic relation between a man and the daughter of his father's sister and between a man and the daughter of his mother's sister, such that biologists would consider mating incestuous in both instances, but Trobrianders consider mating incestuous in one case and not in the other. Anthropologists have documented a great number of societies where marriages between some first cousins are prohibited as incestuous, while marriages between other first cousins are encouraged. Therefore, it is argued that the prohibition against incestuous relations in most societies is not based on or motivated by concerns over biological closeness. Other studies on cousin marriages have found support for a biological basis for the taboo. Also, current supporters of genetic influences on behavior do not argue that genes determine behavior absolutely, but that genes may create predispositions that are affected in various ways by the environment (including culture).

Steve Stewart-Williams argues against the view that incest taboo is a Western phenomenon, arguing that while brother-sister marriage was reported in a diverse range of cultures such Egyptian, Incan, and Hawaiian cultures, it was not a culture-wide phenomenon, being largely restricted to the upper classes. Stewart-Williams argues that these marriages were largely political (their function being to keep power and wealth concentrated in the family) and there is no evidence the siblings were attracted to each other and there is in fact some evidence against it (for example, Cleopatra married two of her brothers but did not have children with them, only having children with unrelated lovers). Stewart-Williams suggests that this was therefore simply a case of social pressure overriding anti-incest instincts. Stewart-Williams also observes that anti-incest behaviour has been observed in other animals and even many plant species (many plants could self-pollinate but have mechanisms that prevent them from doing so).

Sociological explanations
Psychoanalytic theory—in particular, the claimed existence of an Oedipus complex, which is not an instinctual aversion against incest but an instinctual desire—has influenced many theorists seeking to explain the incest taboo using sociological theories.

Exogamy
The anthropologist Claude Lévi-Strauss developed a general argument for the universality of the incest taboo in human societies. His argument begins with the claim that the incest taboo is in effect a prohibition against endogamy, and the effect is to encourage exogamy. Through exogamy, otherwise unrelated households or lineages will form relationships through marriage, thus strengthening social solidarity. That is, Lévi-Strauss views marriage as an exchange of women between two social groups. This theory is based in part on Marcel Mauss's theory of The Gift, which (in Lévi-Strauss' words) argued:

"that exchange in primitive societies consists not so much in economic transactions as in reciprocal gifts, that these reciprocal gifts have a far more important function than in our own, and that this primitive form of exchange is not merely nor essentially of an economic nature but is what he aptly calls "a total social fact", that is, an event which has a significance that is at once social and religious, magic and economic, utilitarian and sentimental, jural and moral."

It is also based on Lévi-Strauss's analysis of data on different kinship systems and marriage practices documented by anthropologists and historians. Lévi-Strauss called attention specifically to data collected by Margaret Mead during her research among the Arapesh. When she asked if a man ever sleeps with his sister, Arapesh replied: "No we don't sleep with our sisters. We give our sisters to other men, and other men give us their sisters." Mead pressed the question repeatedly, asking what would happen if a brother and sister did have sex with one another. Lévi-Strauss quotes the Arapesh response:

"What, you would like to marry your sister? What is the matter with you anyway? Don't you want a brother-in-law? Don't you realize that if you marry another man's sister and another man marries your sister, you will have at least two brothers-in-law, while if you marry your own sister you will have none? With whom will you hunt, with whom will you garden, who will you visit?"

By applying Mauss's theory to data such as Mead's, Lévi-Strauss proposed what he called alliance theory. He argued that, in "primitive" societies—societies not based on agriculture, class hierarchies, or centralized government—marriage is not fundamentally a relationship between a man and a woman, but a transaction involving a woman that forges a relationship—an alliance—between two men.

Some anthropologists argue that nuclear family incest avoidance can be explained in terms of the ecological, demographic, and economic benefits of exogamy.

While Lévi-Strauss generally discounted the relevance of alliance theory in Africa, a particularly strong concern for incest is a fundamental issue among the age systems of East Africa. Here, the avoidance between men of an age-set and their daughters is altogether more intense than in any other sexual avoidance. Paraphrasing Lévi-Strauss's argument, without this avoidance, the rivalries for power between age-sets, coupled with the close bonds of sharing between age-mates, could lead to a sharing of daughters as spouses. Young men entering the age system would then find a dire shortage of marriageable girls, and extended families would be in danger of dying out. Thus, by parading this avoidance of their daughters, senior men make these girls available for younger age-sets and their marriages form alliances that mitigate the rivalries for power.

Endogamy
Exogamy between households or descent groups is typically prescribed in classless societies. Societies that are stratified—that is, divided into unequal classes—often prescribe different degrees of endogamy. Endogamy is the opposite of exogamy; it refers to the practice of marriage between members of the same social group. An example is India's caste system, in which unequal castes are endogamous. Inequality between ethnic groups and races also correlates with endogamy.

An extreme example of this principle, and an exception to the incest taboo, is found among members of the ruling class in certain ancient states, such as the Inca, Egypt, China, and Hawaii; brother–sister marriage (usually between half-siblings) was a means of maintaining wealth and political power within one family. Some scholars have argued that in Roman-governed Egypt this practice was also found among commoners,   but others have argued that this was in fact not the norm.

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

title: Incest taboo


text:
Talk:Inbreeding

Citation needee
Under Humans, sub heading Prevalence, this paragraph exists with no citation while making reference to multiple sources and grand claims, this needs fixing or removal

The general negative outlook and eschewal of inbreeding that is prevalent in the Western world today has roots from over 2000 years ago. Specifically, written documents such as the Bible illustrate that there have been laws and social customs that have called for the abstention from inbreeding. Along with cultural taboos, parental education and awareness of inbreeding consequences have played large roles in minimizing inbreeding frequencies in areas like Europe. That being so, there are less urbanized and less populated regions across the world that have shown continuity in the practice of inbreeding Feiflington (talk) 04:40, 2 January 2021 (UTC)

title: Talk:Inbreeding


text:
Talk:Cheetah

Uncertainty over subspecies
Careful, the cheetah, like the lion, is one of those species which the Cat Specialist Group had trouble with. It is possible that there are only two valid subspecies, a northern subspecies comprising the Asiatic, Northeast and Northwest African cheetahs, and a southern subspecies comprising the Southeast and Southern African cheetahs, similar to the case of lions being divided into a northern subspecies (including North African and Asiatic populations) and southern subspecies (though issues like that of genetic admixture have to be treated with caution). Leo1pard (talk) 16:42, 11 October 2018 (UTC)

 * So what? -- BhagyaMani (talk) 16:58, 11 October 2018 (UTC)

 * As in, big trouble for anyone wishing to use classifications by the Cat Specialist Group about which types are subspecies or not, as if they can be used definitely. Leo1pard (talk) 17:27, 11 October 2018 (UTC)
 * Again: so what is this about? -- BhagyaMani (talk) 17:48, 11 October 2018 (UTC)
 * That you have to be more careful about what you often do, because the CSG admitted that there are a number of things which they aren't sure about, but often, you act as if that's not the case. Leo1pard (talk) 05:24, 12 October 2018 (UTC)

 * I don't need a personal teaching by an amateur!! -- BhagyaMani (talk) 08:20, 12 October 2018 (UTC)
 * How disrespectful. Nobody on Wikipedia knows everything. If you've been editing articles, and someone wants to talk to you about some errors that you made, like what I mentioned about the cheetahs, is this how you're going to treat that person? Leo1pard (talk) 15:50, 12 October 2018 (UTC)

running time of cheetah with maximum speed
]ɱ — Preceding unsigned comment added by Abhi04101997 (talk • contribs) 01:27, 4 November 2018 (UTC)

see it once
thi is wrong because Paratarsotomus macropalpis is fastest animal on earth it is discovered by scientists in 2014 — Preceding unsigned comment added by 2405:205:419D:2ECD:5B05:698D:DB1D:2596 (talk) 10:52, 6 April 2019 (UTC)
 * According to the Paratarsotomus macropalpis article it "the world's fastest land animal relative to body length". The cheetah is faster in absolute terms.  Jts1882 | talk 11:47, 6 April 2019 (UTC)

Author names in text
Hi Tallis40: I don't mean to be disrespectful to authors when removing their names from the content itself. But if we used the names of every 202 authors currently ref'ed in this page, the text would become unreadable. -- BhagyaMani (talk) 14:22, 5 July 2019 (UTC)

 * I think this needs further discussion.
 * Tallis40 wrote in edit summmaries:
 * Names are very important, or even crucial, in this context, for one central reason: there is no ONE definition of ANY of these terms, and most of them lack a clear acoustic definition, and regardless of acoustic definition(s) the use of terms vary between authors. It is crucially important to point out that the terms given here are the ones used by Eklund, Peters, Munro, Weise, or indeed Estes, who also seem to be edited away. Otherwise the reader will get the wrong impression about these terms.
 * No edit done, but if BhagyaMani insists on crediting researcher there *must' be something added about the terminology problem with regard to vocalizations, which indeed was part of this entry just a couple of days ago (when both Eklund and Estes were mentioned). To provide a list of terms without mentioning that those are the terms used by a specific and small group of researchers is misleading and would never be allowed in academic publishing (even at 101 level).
 * In general, an encyclopedia should be presenting the facts as known and the names will be left in the references. Primary research papers have different requirements. This changes when someone makes an exceptionally important contribution to a field or when there is some controversy where different sides must be presented. The earlier version written with the names stated didn't seem to indicate any controversy over the use of the terms. If there is one it should be stated clearly and then the names on both sides can be mentioned. It should also be borne in mind that if there is some controversy, those involved have a conflict of interest (WP:COI). Perhaps any changes should be discussed here first.  Jts1882 | talk 16:13, 5 July 2019 (UTC)
 * Thanks for your comment, Jts1882! And for pointing out the WP:COI editing. Despite this, I don't think it necessary to remove the refs to the published articles. But I removed the cite webs, as no additional or different info about vocalisation of cheetah is provided at these websites.

Please change Palestine to Israel
Why does it mention Palestine instead of Israel?? Please change it to Israel. Its sickening that some individuals take advantage of the wikipedia platform in order to advance their anti Israel agenda. If some would argue Israel was created in 1948, way after the Cheetahs extinction, then one can argue that Israel was founded before Iran (1979) and Syria (1961).

Distribution and habitat

... In Eurasia, Afghanistan, Iran, Iraq, Palestine, Syria, and the Ganga and Indus river valleys in South Asia sheltered large numbers of cheetahs.[33]

EDITED VERSION

... In Eurasia, Afghanistan, Iran, Iraq, Israel, Syria, and the Ganga and Indus river valleys in South Asia sheltered large numbers of cheetahs.[33]

 * . It really depends on what the cited source says. The editor who added that was expanding the article from cited sources and there is no evidence of editing with an ideological agenda.
 * User:Sainsf added that in this edit. you have access to the cited source; what does it actually say?
 * In my opinion, no countries should be mentioned at all, because cheetahs have no notion of political boundaries. Instead, the region covered by these countries should be described. ~Anachronist (talk) 17:50, 31 July 2019 (UTC)
 * The cited source is available online and indeed mentions 'Palestine' as historical range country of the cheetah, see 2nd column on page 25. Just edited this ref. -- BhagyaMani (talk) 18:14, 31 July 2019 (UTC)

Changing citation style without concensus
According to WP:CITEVAR: Editors should not attempt to change an article's established citation style merely on the grounds of personal preference, to make it match other articles, or without first seeking consensus for the change. I don't think the recent changes to use sfn are an improvement and think they should be reverted until there is consensus for such a change.  Jts1882 | talk 08:57, 4 January 2020 (UTC)
 * Fully agree: this change is no improvement and should be reverted. -- BhagyaMani (talk) 09:25, 4 January 2020 (UTC)
 * Hi, sorry for the trouble. I was unaware of this. You can revert the changes I made to the citation style, I am not sure how to perfectly undo it without changing a few other things I fixed between edits. I plan on improving this article for FAC, and will be putting this up for a peer review soon. Probably that would be a good place to discuss the style. Sainsf  (talk · contribs) 09:31, 4 January 2020 (UTC)
 * The reason I didn't revert it immediately was because that would revert the many good changes you have been making. Your work here and at Ocelot is appreciated. The footnote style editing isn't used much in articles on species and biological taxa, it's more appropriate for biographical works where major works are cited many times. Unfortunatly the citation and other edits are mixed across many sections so selective reverts is not possible. I think the best approach would be to revert todays changes (different=934022022&oldid=933939004 these edits) and redo the other changes. I can help with that.  Jts1882 | talk 10:53, 4 January 2020 (UTC)
 * Thank you :) I'm fine with the revert, I'll redo the lost changes later (any help in any part of improving the article is more than welcome). The reason I went for the sfn citation style was that I have around 5 book sources with many useful chapters (see and  for instance) that I plan to use significantly in the article to give it the requisite broadness of an FA, but I was unsure how to cite several chapters from a single book (I will be using almost the whole of the book, do I go for page ranges separated by semicolons in just one citation or write multiple citations for each chapter of each book?) Then I saw the sfn citation style in  Wolf, and remembered its use in an FA I had worked on with other editors (Bluebuck). Thing is, if not sfn, what would be a good way of writing citations in my case that would also look neat enough for FA standards? I am open to suggestions.  Sainsf  (talk · contribs) 12:31, 4 January 2020 (UTC)
 * Well, if there were a large number of books being repeatedly cited, that could be a justification for switching the citation style to use sfn or harvnb. That is what this discussion is for, to establish consensus. However, as the article already has over 200 citations that seems unnecessary, at least at this stage (the feature article reviewers may feel otherwise). Another option is to use the r or rp templates, for instance first use and second use.  There is further information at WP:IBID, WP:CITESHORT and Harvard citation documentation.   Jts1882 | talk 15:10, 4 January 2020 (UTC)
 * Thanks a lot for all the help . I have seen r or rp templates at places but I had never thought of using those. They fit in perfectly here, will use them in the article from now on. Please revert the citation style changes as you feel right, I will pick up my work on the article after that. Sainsf  (talk · contribs) 16:30, 4 January 2020 (UTC)
 * See Help_talk:Citation_Style_1 for another approach, putting the short citations in the main reference list. —  Jts1882 | talk 07:35, 12 April 2020 (UTC)
 * Thanks . I will read it soon. Sainsf  (talk · contribs) 11:42, 12 April 2020 (UTC)

“Palestine”? What is that mythological land?
Cheetahs used to be in Mandate of Palestine or now, Israel & Jordan. “Palestine,” Mordor OT Narnia is a mythological land. AlonTree (talk) 11:55, 1 April 2020 (UTC)
 * Material in Wikipedia has to follow reliable sources. The cited source says Palestine (on p23). If the source mentioned Morder or Narnia, the article would have reflected that sourced information. —  Jts1882 | talk 12:02, 1 April 2020 (UTC)

Article too long
This article is over 188,000K, its far longer than other mammalian species articles. Compared that to lion, cat and wolf at 142,000k, brown bear at 141,000K, tiger at 140,000k and dog at 131,000K. There is no reason why this article can't be trimmed and summarized. LittleJerry (talk) 03:08, 26 April 2020 (UTC)
 * I'll shorten the section Taxonomy. -- BhagyaMani (talk) 09:07, 26 April 2020 (UTC)
 * I think the table in this section can be shortened considerably by removing all those details that are not relevant for taxonomy, e.g. range countries + where it was reintroduced, captive breeding programmes and other content that is either detailed in other sections of this page or on the pages about the subspecies. But before I do so : let me know what you think. -- BhagyaMani (talk) 09:41, 26 April 2020 (UTC)
 * I thought this would be an issue so I was planning to cut down a few sections (mainly Subspecies) but thought of finishing adding details first. No worries, I'll bring it down to 140K. Sainsf  (knock knock · am I there?) 11:02, 26 April 2020 (UTC)

We are down by 30K at least, let me know where else we could cut things down. I will try shortening Reproduction, but the bulk of the article size is mostly refs, may be we should cut them down unless they are necessary? could you let me know why you undid my changes in Habitat, I was trying to condense the material. Sainsf (knock knock · am I there?) 13:44, 26 April 2020 (UTC)
 * Sorry, seems I edited this very shortly after you did; no bad intention. I merely edited refs. -- BhagyaMani (talk) 13:48, 26 April 2020 (UTC)
 * The page still has close to 155,000K. -- BhagyaMani (talk) 13:50, 26 April 2020 (UTC)
 * It's fine.. maybe undo your changes to that section (these 2 changes and ) so that my edits are restored and then edit the refs once again? And do let me know if you have any suggestions to cut down the material, as the readable prose size (59K characters using DYK check tool, Wolf for example has 67K) appears decent to me now (I will still condense it in places) and I observed it does not account for most of the unwanted article size (we can easily cut out 10K more if we remove unnecessary refs).  Sainsf  (knock knock · am I there?) 13:55, 26 April 2020 (UTC)
 * Re-shortened + re-edited refs. For further shortening, I suggest to remove refs to newspapers. In most cases, these are anyway repetitions of peer-reviewed articles. -- BhagyaMani (talk) 15:04, 26 April 2020 (UTC)
 * Okay then. I would probably still aim for <45,000 K but I don't think its a big deal now. LittleJerry (talk) 15:31, 26 April 2020 (UTC)

Article length in Wikipedia is best measured by word count, the word count is reasonable (~9,500 words).

The file size ('WIKITEXT') is NOTHING MUCH TO DO WITH IT, because many normal edits (such as adding references) greatly increase the size without materially increasing the read size of the article for the reader (which is what counts), while only improving the article quality. Good articles, such as this one, normally have large wikitext. GliderMaven (talk) 15:25, 26 April 2020 (UTC)
 * Its reasonable now because there has been much trimming. LittleJerry (talk) 15:31, 26 April 2020 (UTC)
 * I looked back through the history, it didn't seem to have made a lot of difference to word count, my concern was more that you were looking at the wrong metric, and making edits that might actually be harmful based upon it. I haven't managed to go through all the edits. GliderMaven (talk) 22:34, 26 April 2020 (UTC)

 * Thanks for your input everyone, and  but I am confused now. I tried my best to make this article comprehensive enough, got my hand on a few really good sources that explain this topic so well that I had to improve our Wiki article using them, and I was worried about the article length but I saw Wolf and a few others with ~10-12k word count so I went ahead. Then this concern was raised and we had to cut a lot out. It's my request to everyone, before I take this to PR and then FAC, can you explain to me properly if...
 * I made any mistake?
 * Was the part I cut out today too much for the article or should that be put back for comprehensiveness and also because most of it doesn't occur elsewhere on Wiki? The word count if I remember right was <12k yesterday.
 * Are 200+ refs an issue?

 * I want it to do well at FAC and I really should learn from my errors as this is my first big article and I plan to take on big and important articles like this one in future. Thank you. Sainsf  (knock knock · am I there?) 15:41, 26 April 2020 (UTC)

 * 200 refs aren't a problem, lion has more. LittleJerry (talk) 18:33, 26 April 2020 (UTC)

, and  I think the point above that some edits may have done more bad than good as we looked at it the wrong way could hold weight. I mean there are FAs like Passenger pigeon which are way longer and didn't face issues so I can't see why this should except if there is loss of focus, which I'm sure there isn't. So I'm going to open PR now after some cleanup and after I re-add a bit of material which I think should be there for proper coverage. Please discuss anything you wish to at the PR where we can get better consensus instead of here. Thanks, Sainsf  (knock knock · am I there?) 23:08, 26 April 2020 (UTC)
 * Yeah, like I mentioned elsewhere, I'm not sure why the length of related articles should decide how long a given article can be. Passenger pigeon is longer than any articles about extnant pigeons, for example. FunkMonk (talk) 07:55, 27 April 2020 (UTC)

Error in Etymology section
The etymology section has an error. It has a phrase reading चित्रय (cītra); cītra is not correct. The Sanskrit says citraya instead (all short vowels, plus a syllable is forgotten too! How does this happen?). I'm posting this up because I cannot edit this article. 153.33.60.3 (talk) 01:02, 13 October 2020 (UTC)
 * This spelling is referenced by sources. Please check them. -- BhagyaMani (talk) 05:48, 13 October 2020 (UTC)
 * Easy: चि ci त्र tra य ya. It's very basic Devanagari. And anyway, cītra चीत्र is totally unattested; it is not a word. Therefore चित्रय must be the correct one. If you want an alternative argument, we can turn to diachronics. Just off the top of my head, I say with full confidence citraya is more correct: citraya > *cittaya > *cittaa > cītā; compare *cītra > *cītta > *cīt. 153.33.60.3 (talk) 00:28, 14 October 2020 (UTC)
 * Also, the source cited does not say cītra; it literally says "kitraya" (it seems to me that the dictionary uses ⟨k⟩ for what's usually ⟨c⟩—unusual, but it is what it is) 153.33.60.3 (talk) 02:48, 14 October 2020 (UTC)

It's still wrong, but in a different way now: it should be "citraya," not "kitraya." The dictionary contrasts ⟨k⟩ from ⟨k⟩, which represent what is normally ⟨c⟩ and ⟨k⟩, respectively (this is evident from looking at other entries). Why that is, I know not. It does the same thing with ⟨m⟩ for normal ⟨ṁ⟩, and ⟨t⟩ for normal ⟨ṭ⟩; it uses a weird transliteration, and for the sake of uniformity with Wikipedia's standard for Sanskrit transliteration it should read citraya. 153.33.60.3 (talk) 08:09, 14 October 2020 (UTC)
 * Hmm, it seems चित्रक citraka is a better etymology anyway, considering one of its meanings was "hunting-leopard" or "Cheeta [sic]" in Sanskrit. According to the source cited in the article, citraya simply means "painted," which in my opinion seems weaker than "Cheeta." 153.33.60.3 (talk) 08:39, 14 October 2020 (UTC)

Semi-protected edit request on 19 March 2021
Taming:

change: Kublai Khan (1260–1294 BC) to: Kublai Khan (1260-1294 AD)

Kublai Khan's reign was not BC.

100.11.21.132 (talk) 02:18, 19 March 2021 (UTC)
 * ✅. I'm surprised that survived since it was introduced in April 2020. —  Jts1882 | talk 07:16, 19 March 2021 (UTC)

Edits to Social organization
Under Social organization we have some similar information regarding cubs/coalitions.
 * In most cases, a coalition will consist of brothers born in the same litter who stayed together after weaning, but biologically unrelated males are often allowed into the group; in the Serengeti 30% members in coalitions are unrelated males.
 * If a cub is the only male in a litter he will typically join an existing group, or form a small group of solitary males with two or three other lone males who may or may not be territorial. In the Kalahari Desert around 40% of the males live in solitude.

I have grouped these two portions together. And now, the following info regarding coalitions is together. But, the original sentences had two sources, and I have split the sentences, although I copied both sources, Nowak and Hunter. I don't know if the sources need to be adjusted, as I can't access many pages of "Wildcats of the World" (Luke Hunter). Please review and help, if you can. Thanks,  Tribe of Tiger Let's Purrfect!  04:05, 3 August 2021 (UTC)
 * "If a cub is the only male in a litter he will typically join an existing group, or form a small group of solitary males with two or three other lone males who may or may not be territorial. In the Kalahari Desert around 40% of the males live in solitude. A coalition generally has a greater chance of encountering and acquiring females for mating, however, its large membership demands greater resources than do solitary males."
 * , that book is available for download on zbooks. . LittleJerry (talk) 22:01, 3 August 2021 (UTC)
 * , thanks, I will check this! Very kind of you....  Tribe of Tiger Let's Purrfect!  04:53, 5 August 2021 (UTC)

Semi protection reason
From the log it appears the page is semi protected since 2010. The discussion at WP:RFPP seems to no longer be in the archives, and there are no notice as why the page is protected even here.

Anyone remember the cause and whether it is still applicable ? CrocodilienAnonyme (talk) 13:45, 27 September 2021 (UTC)

 * It's a pretty popular page and was probably vandalized pretty frequently before being semi-protected. --SilverTiger12 (talk) 14:02, 27 September 2021 (UTC)

Thanks, that was ten years ago, but I guess there are no reason it’s vandale attracting status changed.

SilverTiger12 May I pet you as a thanks ? :D CrocodilienAnonyme (talk) 14:09, 27 September 2021 (UTC)

Featured picture scheduled for POTD
Hello! This is to let editors know that File:Cheetah (Acinonyx jubatus) cub.jpg, a featured picture used in this article, has been selected as the English Wikipedia's picture of the day (POTD) for November 16, 2021. A preview of the POTD is displayed below and can be edited at Template:POTD/2021-11-16. For the greater benefit of readers, any potential improvements or maintenance that could benefit the quality of this article should be done before its scheduled appearance on the Main Page. If you have any concerns, please place a message at Wikipedia talk:Picture of the day. Thank you! Cwmhiraeth (talk) 12:59, 25 October 2021 (UTC)

Why does this include their ESA conservation status?
I thought it was standard procedure to list the IUCN Red List, and, if applicable, CITES designations, for the conservation status of any animal species, which reflect worldwide consensus. Why use an American system for a species that's not even found in the United States? --An anonymous username, not my real name (talk) 00:53, 12 January 2022 (UTC)
 * Good point !!! It is NOT at all needed in the box. – BhagyaMani (talk) 07:29, 12 January 2022 (UTC)

Semi-protected edit request on 7 April 2022
Please remove these three phrases:

neglect of cubs by mothers Cheetahs are poor breeders in captivity, while wild individuals are far more successful Though she tries to make minimal noise she usually can not defend her litter from these predators.

and replace them with these three:

maternal neglect Wild cheetahs are far more successful breeders than captive cheetahs Despite trying to make minimal noise, she cannot generally defend her litter from predators.

"Maternal neglect" is a common term, and while most results (unsurprisingly) are human-related, the concept itself isn't. "Can not" is not normal, a common is beneficial, and the identity of "these" predators isn't given. All three phrases are shorter without losing anything of significance. 120.21.112.28 (talk) 01:18, 7 April 2022 (UTC)

 * ✅ ★Ama   TALK   CONTRIBS  16:45, 5 May 2022 (UTC)

Cheetahs in India
Two sets now present in Kuno national park, MP India and historical range. 2604:CA00:138:33BB:0:0:C61:3212 (talk) 16:19, 18 February 2023 (UTC)

Incorrect units used for acceleration
"The researchers suggested that a hunt consists of two phases—an initial fast acceleration phase when the cheetah tries to catch up with the prey, followed by slowing down as it closes in on it, the deceleration varying by the prey in question. The peak acceleration observed was 2.5 m/s (8.2 ft/s), while the peak deceleration value was 7.5 m/s (25 ft/s)."

The incorrect units used m/s and ft/s are of speed, not acceleration. Acceleration is a rate of change of velocity with time and has to include a time squared component. It is written in the SI system as m.s-2 (ft.s-2 archaic). KlinkyWik (talk) 08:19, 2 May 2023 (UTC)
 * It's also not clear where the numbers come from. One of the Wilson et al (2013, Nature) papers says the average deceleration in successful hunts was -7.5ms-2, while Fig 3d shows it can reach double that. Fig 3d also shows accelerations up to about -12ms-2, although I don't see an average mentioned. The RS paper says the fastest (GPS-derived) linear acceleration was 7.5ms-2". There is also a ridiculous amount of precision in that paragraph when describing the maximum speeds. —  Jts1882 | talk 09:18, 2 May 2023 (UTC)

Cheetah Reintroduction in Saudi Arabia.
1. https://www.arabnews.com/node/2297351/saudi-arabia?fbclid=IwAR0YCqNJtTk0Qktrpv9gpPMd8nXAduamuyqQCB5mNjpuY38-wq0zoyTy_n0_aem_th_AUpbsfGMfvl5ZZVjP3EEPLQ3w5GER4JILERfs-JYVNBriBQVKWdBa05hRVhS6QalpCY&mibextid=S66gvF

2. https://www.saudigazette.com.sa/article/632156?fbclid=IwAR2Sfb3wCFOwVzhiExjF7Q34I6U9AETuMhiI9PYIn_yEearSeHv9NfewN3c_aem_th_AUppqgthZEFNtkwJq_cBHkDMbrAm_MBBGbG7nyVIyJ_vGaeIvRqT1QUkVYUJGSvWFBo&mibextid=Zxz2cZ Ovie11 (talk) 01:33, 29 May 2023 (UTC)

Semi-protected edit request on 9 July 2023
Please change:

is a large cat native to Africa and Southwest Asia (today restricted to central Iran).

to

is a large cat native to Africa and central Iran.

This would bring the introductory sentence back to what it was before a change in February 2023.

The current wording is far too confusing – it sounds like we're saying that today it only lives in Iran, instead of Africa and Iran.

194.105.229.8 (talk) 19:17, 9 July 2023 (UTC)
 * ✅ 💜 melecie   talk  - 00:12, 10 July 2023 (UTC)

Just two references (+pdf) of the many scientific research articles that would better inform this page
In connection to this sentence "... it has evolved specialized adaptations for speed, including a light build, long thin legs and a long tail" which lacks any serious/significant information, with references, on physiological and anatomical adaptation for speed.

Williams, T. M., et al. "Skeletal muscle histology and biochemistry of an elite sprinter, the African cheetah." Journal of Comparative Physiology B 167 (1997): 527-535.

https://williams.eeb.ucsc.edu/wp-content/uploads/2015/09/CheetahMuscleHistology_WilliamsEtAl1997.pdf

Hudson, Penny E., Sandra A. Corr, and Alan M. Wilson. "High speed galloping in the cheetah (Acinonyx jubatus) and the racing greyhound (Canis familiaris): spatio-temporal and kinetic characteristics." Journal of Experimental Biology 215.14 (2012): 2425-2434.

https://www.originalwisdom.com/wp-content/uploads/bsk-pdf-manager/2019/10/Hudson-et-al_2012_High-speed-galloping-in-the-cheetah-and-the-racing-greyhound.pdf Richard Hawkins (talk) 19:54, 24 August 2023 (UTC)

 * Okay... so why aren't you gleaning information from those sources and uptaing the article? - UtherSRG (talk) 10:58, 25 August 2023 (UTC)
 * Because this page, unlike any other I have worked on is closed. Richard Hawkins (talk) 11:03, 25 August 2023 (UTC)
 * If you are extended-confirmed, you should be able to edit it as it is semi-protected., not full protected. SilverTiger12 (talk) 14:13, 25 August 2023 (UTC)
 * As SilverTiger12 said. In addition, if you are not able to edit it, you can propose specific changes here via the  template. - UtherSRG (talk) 14:17, 25 August 2023 (UTC)

Taxonomy incorrect?
NCBI lists cheetahs being in Acinonyx, a sister clade to Felinae. https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Tree&id=32536&lvl=3&lin=f&keep=1&srchmode=1&unlock Aredridel (talk) 15:52, 10 September 2023 (UTC)

 * The ASM's MDD lists it in Felinae. https://www.mammaldiversity.org/explore.html#genus=Acinonyx&species=jubatus&id=1005979 We generally follow the IUCN and ASM. - UtherSRG (talk) 16:11, 10 September 2023 (UTC)
 * IUCN lists it in Acinonyx: https://www.iucnredlist.org/species/219/124366642#taxonomy 172.56.193.150 (talk) 16:26, 10 September 2023 (UTC)
 * Oh, doh, no, that's genus not subfamily. IUCN doesn't list it (at least in the red list) Aredridel (talk) 16:31, 10 September 2023 (UTC)
 * The NCBI does place Acinonyx in Acinonychinae, which reflects early classifications separating the cheetah from the other cats based on its "non-retractible" claws. This classification fell out of favour on morphological grounds (the claws are sort of retractible after all) before molecular data showed the cheetah to be more closely related to the puma and jaguarundi. The NCBI disclaimer saying "The NCBI taxonomy database is not an authoritative source for nomenclature or classification" is pertinent here. —  Jts1882 | talk 17:13, 10 September 2023 (UTC)

Cheetah limb bones robustness
About my last edit:

That is exactly what I said. I don't think I expressed it in the best way. Correct? The length of a cheetah's femur in relation to body mass is 87 mm/kg⅓. That of a greyhound is 69 mm/kg⅓. In addition, the diameter of the midshaft of cheetah bones is larger than that of greyhounds relative to the length of the bone. For example, in cheetahs, the diameter equals 8.07 % of the femur length, and 7.53 % of the femur length in greyhounds. The diameter equals 7.27 % of the tibia length in cheetahs, and 7.02 % in greyhounds. (Relative diameters are personal calculations from length and diameter averages also made by me; See Hudson 2011).

There is a popular belief that cheetahs are too fragile, but this is not so true. There are more graceful animals out there. An animal that can accelerate quickly (0-97 Km/h in less than 3 seconds), needs strong limb bones. Don't you think so?

Also, cheetahs seem to have a more elongated calcaneus than greyhounds which would help them to generate more torque on the ankle joint.

LeandroPucha (talk) 19:19, 22 September 2023 (UTC)

where do cheetahs live
their habit 207.89.46.249 (talk) 14:31, 7 February 2024 (UTC)

 * It's in the article: Cheetah. - UtherSRG (talk) 14:43, 7 February 2024 (UTC)

Incorrect map of India
Map of India has severe inaccuracies and seems to have been done with mala fide intentions. Jammu & Kashmir, Punjab and Aksai Chin which are inalienable and integral part of India as held by Govt. of India, are shown either as parts of Pakistan and China or marked as separate territories. Even if the map is drawn keeping in mind UN disputed territories resolution, disputed territories of Pakistan occupied Kashmir and Aksai chin should have also been marked separately, which isnt the case. Also Punjab state of India which clearly isnt disputed by any other UN member is marked as a separate country/territory which is highly objectionable. Kindly take note of it and revise the map Mohitkumar0121210 (talk) 19:22, 22 April 2024 (UTC)

 * I think you are asking on the wrong article. - UtherSRG (talk) 00:47, 23 April 2024 (UTC)
 * Its not the wrong article, map of cheetah habitat clearly shows India on the right. The distortion of the map is clearly visible and needs a rectification Mohitkumar0121210 (talk) 02:31, 23 April 2024 (UTC)
 * I too thought that you asked on the wrong page. But since you insist, just go ahead + change the map yourself. Then we can decide whether your changes are acceptable. – BhagyaMani (talk) 04:34, 23 April 2024 (UTC)
 * I've replace the range map with a cropped version of the same image that avoids the issue. —  Jts1882 | talk 06:47, 23 April 2024 (UTC)
 * well okay, since you've cropped it out, I think it doesnt need complete replacement anymore. Its acceptable for now but could require India's addition in the map in future since cheetah population in India has reached 26 after reintroduction from Africa Mohitkumar0121210 (talk) 07:16, 23 April 2024 (UTC)

Semi-protected edit request on 6 May 2024
The species of the cheetah is not considered a large cat since it cannot roar. I request we change the page to say that cheetahs are considered small cats but are about the same size as felines considered as large cats. Thanks you 2601:80:477F:82F0:AD97:6C0E:7435:C972 (talk) 14:29, 6 May 2024 (UTC)
 * Red information icon with gradient background.svg Not done: please provide reliable sources that support the change you want to be made. M.Bitton (talk) 14:50, 6 May 2024 (UTC)
 * Large cat as in size. Note that it does not state the cheetah is a Big cat, which is used to refer to the cats you’re talking about The Great Mule of Eupatoria (talk) 06:34, 19 June 2024 (UTC)

title: Talk:Cheetah


text:
Chromatic aberration

In optics, chromatic aberration (CA), also called chromatic distortion, color aberration, color fringing, or purple fringing, is a failure of a lens to focus all colors to the same point. It is caused by dispersion: the refractive index of the lens elements varies with the wavelength of light. The refractive index of most transparent materials decreases with increasing wavelength. Since the focal length of a lens depends on the refractive index, this variation in refractive index affects focusing. Since the focal length of the lens varies with the colour of the light different colours of light are brought to focus at different distances form the lens or with different levels of magnification. Chromatic aberration manifests itself as "fringes" of color along boundaries that separate dark and bright parts of the image.

Types
There are two types of chromatic aberration: axial (longitudinal), and transverse (lateral). Axial aberration occurs when different wavelengths of light are focused at different distances from the lens (focus shift). Longitudinal aberration is typical at long focal lengths. Transverse aberration occurs when different wavelengths are focused at different positions in the focal plane, because the magnification and/or distortion of the lens also varies with wavelength. Transverse aberration is typical at short focal lengths. The ambiguous acronym LCA is sometimes used for either longitudinal or lateral chromatic aberration.

The two types of chromatic aberration have different characteristics, and may occur together. Axial CA occurs throughout the image and is specified by optical engineers, optometrists, and vision scientists in diopters. It can be reduced by stopping down, which increases depth of field so that though the different wavelengths focus at different distances, they are still in acceptable focus. Transverse CA does not occur on the optical axis of an optical system (which is typically the center of the image) and increases away from the optical axis. It is not affected by stopping down since it is caused by the different magnification of the lens with each colour of light.

In digital sensors, axial CA results in the red and blue planes being defocused (assuming that the green plane is in focus), which is relatively difficult to remedy in post-processing, while transverse CA results in the red, green, and blue planes being at different magnifications (magnification changing along radii, as in geometric distortion), and can be corrected by radially scaling the planes appropriately so they line up.

Minimization

In the earliest uses of lenses, chromatic aberration was reduced by increasing the focal length of the lens where possible. For example, this could result in extremely long telescopes such as the very long aerial telescopes of the 17th century. Isaac Newton's theories about white light being composed of a spectrum of colors led him to the conclusion that uneven refraction of light caused chromatic aberration (leading him to build the first reflecting telescope, his Newtonian telescope, in 1668. )

Modern telescopes, as well as other catoptric and catadioptric systems, continue to use mirrors, which have no chromatic aberration.

There exists a point called the circle of least confusion, where chromatic aberration can be minimized. It can be further minimized by using an achromatic lens or achromat, in which materials with differing dispersion are assembled together to form a compound lens. The most common type is an achromatic doublet, with elements made of crown and flint glass. This reduces the amount of chromatic aberration over a certain range of wavelengths, though it does not produce perfect correction. By combining more than two lenses of different composition, the degree of correction can be further increased, as seen in an apochromatic lens or apochromat. "Achromat" and "apochromat" refer to the type of correction (2 or 3 wavelengths correctly focused), not the degree (how defocused the other wavelengths are), and an achromat made with sufficiently low dispersion glass can yield significantly better correction than an achromat made with more conventional glass. Similarly, the benefit of apochromats is not simply that they focus three wavelengths sharply, but that their error on other wavelengths is also quite small.

Many types of glass have been developed to reduce chromatic aberration. These are low dispersion glass, most notably, glasses containing fluorite. These hybridized glasses have a very low level of optical dispersion; only two compiled lenses made of these substances can yield a high level of correction.

The use of achromats was an important step in the development of optical microscopes and telescopes.

An alternative to achromatic doublets is the use of diffractive optical elements. Diffractive optical elements are able to generate arbitrary complex wave fronts from a sample of optical material which is essentially flat. Diffractive optical elements have negative dispersion characteristics, complementary to the positive Abbe numbers of optical glasses and plastics. Specifically, in the visible part of the spectrum diffractives have a negative Abbe number of −3.5. Diffractive optical elements can be fabricated using diamond turning techniques.

Telephoto lenses using diffractive elements to minimize chromatic aberration are commercially available from Canon and Nikon for interchangeable-lens cameras; these include 800mm f/6.3, 500mm f/5.6, and 300mm f/4 models by Nikon (branded as "phase fresnel" or PF), and 800mm f/11, 600mm f/11, and 400mm f/4 models by Canon (branded as "diffractive optics" or DO). They produce sharp images with reduced chromatic aberration at a lower weight and size than traditional optics of similar specifications and are generally well-regarded by wildlife photographers.

Mathematics of chromatic aberration minimization
For a doublet consisting of two thin lenses in contact, the Abbe number of the lens materials is used to calculate the correct focal length of the lenses to ensure correction of chromatic aberration. If the focal lengths of the two lenses for light at the yellow Fraunhofer D-line (589.2 nm) are f1 and f2, then best correction occurs for the condition:
 * $$f_1 \cdot V_1 + f_2 \cdot V_2 = 0$$

where V1 and V2 are the Abbe numbers of the materials of the first and second lenses, respectively. Since Abbe numbers are positive, one of the focal lengths must be negative, i.e., a diverging lens, for the condition to be met.

The overall focal length of the doublet f is given by the standard formula for thin lenses in contact:
 * $$\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}$$

and the above condition ensures this will be the focal length of the doublet for light at the blue and red Fraunhofer F and C lines (486.1 nm and 656.3 nm respectively). The focal length for light at other visible wavelengths will be similar but not exactly equal to this.

Chromatic aberration is used during a duochrome eye test to ensure that a correct lens power has been selected. The patient is confronted with red and green images and asked which is sharper. If the prescription is right, then the cornea, lens and prescribed lens will focus the red and green wavelengths just in front, and behind the retina, appearing of equal sharpness. If the lens is too powerful or weak, then one will focus on the retina, and the other will be much more blurred in comparison.

Image processing to reduce the appearance of lateral chromatic aberration
In some circumstances, it is possible to correct some of the effects of chromatic aberration in digital post-processing. However, in real-world circumstances, chromatic aberration results in permanent loss of some image detail. Detailed knowledge of the optical system used to produce the image can allow for some useful correction. In an ideal situation, post-processing to remove or correct lateral chromatic aberration would involve scaling the fringed color channels, or subtracting some of a scaled versions of the fringed channels, so that all channels spatially overlap each other correctly in the final image.

As chromatic aberration is complex (due to its relationship to focal length, etc.) some camera manufacturers employ lens-specific chromatic aberration appearance minimization techniques. Almost every major camera manufacturer enables some form of chromatic aberration correction, both in-camera and via their proprietary software. Third party software tools such as PTLens are also capable of performing complex chromatic aberration appearance minimization with their large database of cameras and lens.

In reality, even theoretically perfect post-processing based chromatic aberration reduction-removal-correction systems do not increase image detail as well as a lens that is optically well-corrected for chromatic aberration would for the following reasons:
 * Rescaling is only applicable to lateral chromatic aberration but there is also longitudinal chromatic aberration
 * Rescaling individual color channels result in a loss of resolution from the original image
 * Most camera sensors only capture a few and discrete (e.g., RGB) color channels but chromatic aberration is not discrete and occurs across the light spectrum
 * The dyes used in the digital camera sensors for capturing color are not very efficient so cross-channel color contamination is unavoidable and causes, for example, the chromatic aberration in the red channel to also be blended into the green channel along with any green chromatic aberration.

The above are closely related to the specific scene that is captured so no amount of programming and knowledge of the capturing equipment (e.g., camera and lens data) can overcome these limitations.

Photography
The term "purple fringing" is commonly used in photography, although not all purple fringing can be attributed to chromatic aberration. Similar colored fringing around highlights may also be caused by lens flare. Colored fringing around highlights or dark regions may be due to the receptors for different colors having differing dynamic range or sensitivity – therefore preserving detail in one or two color channels, while "blowing out" or failing to register, in the other channel or channels. On digital cameras, the particular demosaicing algorithm is likely to affect the apparent degree of this problem. Another cause of this fringing is chromatic aberration in the very small microlenses used to collect more light for each CCD pixel; since these lenses are tuned to correctly focus green light, the incorrect focusing of red and blue results in purple fringing around highlights. This is a uniform problem across the frame, and is more of a problem in CCDs with a very small pixel pitch such as those used in compact cameras. Some cameras, such as the Panasonic Lumix series and newer Nikon and Sony DSLRs, feature a processing step specifically designed to remove it.

On photographs taken using a digital camera, very small highlights may frequently appear to have chromatic aberration where in fact the effect is because the highlight image is too small to stimulate all three color pixels, and so is recorded with an incorrect color. This may not occur with all types of digital camera sensor. Again, the de-mosaicing algorithm may affect the apparent degree of the problem.

Black-and-white photography
Chromatic aberration also affects black-and-white photography. Although there are no colors in the photograph, chromatic aberration will blur the image. It can be reduced by using a narrow-band color filter, or by converting a single color channel to black and white. This will, however, require longer exposure (and change the resulting image). (This is only true with panchromatic black-and-white film, since orthochromatic film is already sensitive to only a limited spectrum.)

Electron microscopy
Chromatic aberration also affects electron microscopy, although instead of different colors having different focal points, different electron energies may have different focal points.

title: Chromatic aberration