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Exogamy is the social norm of marrying outside one's social group. The group defines the scope and extent of exogamy, and the rules and enforcement mechanisms that ensure its continuity. One form of exogamy is dual exogamy, in which two groups engage in continual wife exchange. [1]


In social science, exogamy is viewed as a combination of two related aspects: biological and cultural. Biological exogamy is marriage of nonblood-related beings, regulated by forms of incest law. Cultural exogamy is marrying outside a specific cultural group; the opposite being endogamy, marriage within a social group.

Biological exogamy

In biology, exogamy more generally refers to the mating of individuals who are relatively less related genetically: that is, outbreeding as opposed to inbreeding. This benefits the offspring as it reduces the risk of the offspring inheriting two copies of a defective gene. Increasing the genetic diversity of the offspring is thought to improve their chances of surviving to reproduce themselves.

Exogamy in humans

Scientists surmise that the drive in humans, as in many animals, to engage in exogamy (outbreeding) is evolutionarily adaptive, as it reduces the risk of children having genetic defects caused by inbreeding, as a result of inheriting two copies of a recessive gene. [2] The genetic principles involved apply to all species, not just humans.

Individuals who breed with more 'exotic' (or distant) partners and avoid incestuous relationships tend to have healthier offspring, due to the benefits of heterosis. Maladapative genetic conditions are more likely to be inherited where inbreeding takes place, or within relatively closed populations over long periods of time. [3] An example is cystic fibrosis, which has developed as a genetic disease inherited chiefly by people of European descent. Another genetic disease specific to certain populations is sickle-cell anemia, for which people of African descent are more at risk; it developed among Africans together with higher immunity to malaria, which is endemic on the continent. Offspring may not always inherit such adaptations that evolved in specific geographic areas. Genetic concerns are not the only cause for exogamy; many social and political aspects support this system of marriage, throughout societies and species.

Cultural exogamy

Cultural exogamy is the custom of marrying outside a specified group of people to which a person belongs. Thus, persons may be expected to marry outside their totem clan(s) or other groups, in addition to outside closer blood relatives.

Researchers have proposed different theories to account for the origin of exogamy. Edvard Westermarck said an aversion to marriage between blood relatives or near kin emerged with a parental deterrence of incest. From a genetic point of view, aversion to breeding with close relatives results in fewer congenital diseases. If one person has a faulty gene, breeding outside his group increases the chances that his partner will have another functional type gene and their child may not suffer the defect. Outbreeding favours the condition of heterozygosity, that is having two nonidentical copies of a given gene. J. F. McLennan [4] holds that exogamy was due originally to a scarcity of women among small bands. Men were obliged to seek wives from other groups, including marriage by capture, and exogamy developed as a cultural custom.

Émile Durkheim [5] derives exogamy from totemism. He said that a people had religious respect for the blood of a totemic clan, for the clan totem is a god and is present especially in the blood, a sacred substance.

Morgan [6] maintains that exogamy was introduced to prevent marriage between blood relations, especially between brother and sister, which had been common in an earlier state of promiscuity. Frazer [7] says that exogamy was begun to maintain the survival of family groups, especially when single families became larger political groups. Lang [8] in 1905 argued against Howitt's claim of group marriage and claims that so-called group marriage is only tribe-regulated licence.

Claude Lévi-Strauss introduced the "Alliance Theory" of exogamy, [9] that is, that small groups must force their members to marry outside so as to build alliances with other groups. According to this theory, groups that engaged in exogamy would flourish, while those that did not would all die, either literally or because they lacked sufficient ties for cultural and economic exchange, leaving them at a disadvantage. The exchange of men or women served as a uniting force between groups.

Dual exogamy

Dual exogamy is a traditional form of arranging marriages in numerous modern societies and in many societies described in classical literature. It can be matrilineal or patrilineal. It is practiced by some Australian tribes, [10] historically widespread in the Turkic societies, [11] [12] Taï societies (Ivory Coast), [13] Eskimo, [14] among Ugrians [15] and others. In tribal societies, the dual exogamy union lasted for many generations, ultimately uniting the groups initially unrelated by blood or language into a single tribe or nation.

Linguistic exogamy

Linguistic exogamy is a form of cultural exogamy in which marriage occurs only between speakers of different languages. The custom is common among indigenous groups in the northwest Amazon, such as the Tucano tribes. [16] It is also used to describe families in Atlantic Canada with a Francophone and an Anglophone parent.[ citation needed ]

See also

Related Research Articles

Incest is human sexual activity between family members or close relatives. This typically includes sexual activity between people in consanguinity, and sometimes those related by affinity, adoption, clan, or lineage.

Inbreeding Production of offspring from the mating of individuals of a breed who are more closely related than the average members of the breed.

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 or recessive traits resulting from incestuous sexual relationships and consanguinity.

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 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.

Westermarck effect Hypothesis that those who grow up together become desensitized to sexual attraction

The Westermarck effect, also known as reverse sexual imprinting, is a psychological hypothesis that people who live in close domestic proximity during the first few years of their lives become desensitized to sexual attraction. This hypothesis was first proposed by Finnish anthropologist Edvard Westermarck in his book The History of Human Marriage (1891) as one explanation for the incest taboo.

Kinship Human relationship term; web of social relationships that form an important part of the lives of most humans in most societies; form of social connection

In anthropology, kinship is the web of social relationships that form an important part of the lives of all humans in all societies, although its exact meanings even within this discipline are often debated. Anthropologist Robin Fox states that "the study of kinship is the study of what man does with these basic facts of life – mating, gestation, parenthood, socialization, siblingship etc." Human society is unique, he argues, in that we are "working with the same raw material as exists in the animal world, but [we] can conceptualize and categorize it to serve social ends." These social ends include the socialization of children and the formation of basic economic, political and religious groups.

Totem spirit being, sacred object, or symbol that serves as an emblem of a group of people, such as a family, clan, lineage, or tribe

A totem is a spirit being, sacred object, or symbol that serves as an emblem of a group of people, such as a family, clan, lineage, or tribe.

Endogamy is the practice of marrying within a specific social group, caste, or ethnic group, rejecting those from others as unsuitable for marriage or other close personal relationships.

Consanguinity Property of being from the same kinship as another person

Consanguinity is the property of being from the same kinship as another person. In that aspect, consanguinity is the quality of being descended from the same ancestor as another person.

Assortative mating is a mating pattern and form of sexual selection in which individuals with similar phenotypes mate with one another more frequently than would be expected under a random mating pattern. Some examples of similar phenotypes are body size or skin coloration or pigmentation. Assortative mating can increase genetic relatedness within the family and is the inverse of disassortative mating.

In Hindu culture, the term gotra is considered to be equivalent to lineage. It broadly refers to people who are descendants in an unbroken male line from a common male ancestor or patriline. Generally the gotra forms an exogamous unit, with the marriage within the same gotra being prohibited by custom, being regarded as incest. The name of the gotra can be used as a surname, but it is different from a surname and is strictly maintained because of its importance in marriages among Hindus, especially among the higher castes. Pāṇini defines gotra for grammatical purposes as apatyam pautraprabhrti gotram, which means "the word gotra denotes the progeny beginning with the son's son." When a person says "I am Vipparla-gotra", he means that he traces his descent from the ancient sage Vipparla by unbroken male descent.

Inbreeding depression is the reduced biological fitness in a given population as a result of inbreeding, or breeding of related individuals. Population biological fitness refers to an organism's ability to survive and perpetuate its genetic material. Inbreeding depression is often the result of a population bottleneck. In general, the higher the genetic variation or gene pool within a breeding population, the less likely it is to suffer from inbreeding depression.

In biology, outbreeding depression is when crosses between two genetically distant groups or populations results in a reduction of fitness. The concept is in contrast to inbreeding depression, although the two effects can occur simultaneously. Outbreeding depression is a risk that sometimes limits the potential for genetic rescue or augmentations. Therefore it is important to consider the potential for outbreeding depression when crossing populations of a fragmented species. It is considered postzygotic response because outbreeding depression is noted usually in the performance of the progeny. Some common cases of outbreeding depression have arisen from crosses between different species or populations that exhibit fixed chromosomal differences.

Human–animal marriage is a marriage between a (non-human) animal and a human. This topic has appeared in mythology and magical fiction. In the 21st century there have been numerous reports from around the world of humans marrying their pets and other animals. Human–animal marriage is often seen in accordance with zoophilia, although they are not necessarily linked. Although animal-human marriage is not mentioned specifically in national laws, the act of engaging in sexual acts with an animal is illegal in many countries under animal abuse laws.

Cousin marriage Marriage between those with common grandparents or other recent ancestors

A cousin marriage is a marriage where the partners are cousins. The practice was common in earlier times, and continues to be common in some societies today, though in some jurisdictions such marriages are prohibited. Worldwide, more than 10% of marriages are between first or second cousins. Cousin marriage is an important topic in anthropology and alliance theory.

The alliance theory, also known as the general theory of exchanges, is a structuralist method of studying kinship relations. It finds its origins in Claude Lévi-Strauss's Elementary Structures of Kinship (1949) and is in opposition to the functionalist theory of Radcliffe-Brown. Alliance theory has oriented most anthropological French works until the 1980s; its influences were felt in various fields, including psychoanalysis, philosophy and political philosophy.

Structural endogamy

Structural endogamy is a network concept that provides a means of finding the boundaries of endogamy in a community, using simply the genealogical and marriage linkages. The concept is related to that of structural cohesion. The examples are made with free tool Pajek. Another name for structural endogamy is (marital) relinking, which comes out of French social anthropology, and the study of how communities are formed through couples marrying who are already linked: linked, that is, by chains of kinship and marriage, as in circles of intermarrying families, or marriages between people with one or more ancestors in common. Many of the marriages represented in the Turkish nomads figure are with cousins, for example. But relinking also occurs without blood marriages, as in the example from the Mexican village of Belén Atzitzi-mititlán within Apetatitlán de Antonio Carvajal.

Cousin marriage is allowed and often encouraged throughout the Middle East. The bint 'amm marriage, or marriage with one's father's brother's daughter is especially common, especially in tribal and traditional communities. Anthropologists have debated the significance of the practice; some view it as the defining feature of the Middle Eastern kinship system while others note that overall rates of cousin marriage have varied sharply between different Middle Eastern communities. There is very little numerical evidence of rates of cousin marriage in the past.

Castes in India: Their Mechanism, Genesis and Development was a paper read by B. R. Ambedkar at an anthropological seminar of Alexander Goldenweiser in New York on 9 May 1916. It was later published in volume XLI of Indian Antiquary in May 1917. In the same year, Ambedkar was awarded a PhD degree by Columbia University on this topic. In 1979, the Education Department of the Government of Maharashtra (Bombay) published this article in the collection of Ambedkar's writings and speeches Volume 1; later, it was translated in many languages.

Consanguine marriage is marriage between individuals who are closely related. Though it may involve incest, it implies more than the sexual nature of incest. In a clinical sense, marriage between two family members who are second cousins or closer qualifies as consanguineous marriage. This is based on the gene copies their offspring may receive. Though these unions are still prevalent in some communities, as seen across the Greater Middle East region, many other populations have seen a great decline in intra-family marriages.

Filter theory is a sociological theory concerning dating and mate selection. It proposes that social structure limits the number of eligible candidates for a mate. Most often, this takes place due to homogamy, as people seek to date and marry only those similar to them. Homogamy is the idea of marriage between spouses who share similar characteristics, where heterogamy denotes marriage between spouses of different characteristics. The idea of "opposites attract: is heterogamous as well as the idea that one spouse has complementing, not similar characteristics to the other.


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