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Exogamy is a social arrangement where marriage is allowed only outside a social group. The social groups define the scope and extent of exogamy, and the rules and enforcement mechanisms that ensure its continuity. In social studies, exogamy is viewed as a combination of two related aspects: biological and cultural. Biological exogamy is marriage of non blood-related beings, regulated by forms of incest law. A form of exogamy is dual exogamy, in which two groups engage in continual wife exchange.[1] Cultural exogamy is the marrying outside of a specific cultural group. The opposite of exogamy is endogamy, a marriage within a social group.

Biological exogamy[edit]

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. By increasing the genetic diversity of the offspring, it is thought to improve their chances of surviving to reproduce themselves.

Exogamy in humans[edit]

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.

Various ethnic groups still practice exogamy as part of their ancient heritage practices, notably northern Scandinavian cultures.

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[edit]

Cultural exogamy is the custom of marrying outside a specified group of people to which a person belongs. Thus, a person 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 non-identical 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 present is 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 in order 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[edit]

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 Finnic people[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[edit]

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 used to describe families in Atlantic Canada with a Francophone and an Anglophone parent.[citation needed]

See also[edit]


  1. ^ New Zealand Slavonic Journal, Victoria University of Wellington, 2002, Volumes 35-36, p.81 OCLC 297663912
  2. ^ Thornhill, N. 1993. The Natural History of Inbreeding and Outbreeding: Theoretical and Empirical Perspectives. The University of Chicago Press, Chicago.
  3. ^ Dorsten, L., Hotchkiss, L., and King, T. 1999. "The Effect of Inbreeding on Early Childhood Mortality: Twelve Generations of an Amish Settlement," in Demography Vol. 36. No. 2. pp. 263-271.
  4. ^ McLennan, J. F. (1888). "The Origin of Exogamy". The English Historical Review 3 (9): 94–104. 
  5. ^ Fraser, James George (1910). Totemism and Exogamy Vol. IV. New York: Cosimo Inc. pp. 100–102. 
  6. ^ Morgan, Lewis Henry (1871). "Systems of Consanguinity and Affinity of the Human Family". Smithsonian Contributions to Knowledge (Smithsonian Institution) 41 (2). 
  7. ^ Frazer, James George (1910). Totemism and Exogamy Vol. IV. New York: Cosimo Inc. p. 95. 
  8. ^ Lang, Andrew (1905). Secret of the Totem. London: Longmans, Green and Co. p. 56. 
  9. ^ "Alliance Theory". Encyclopedia Britannica. Retrieved 15 March 2012. 
  10. ^ Bose J.K., 1980, Glimpses of Tribal Life in North-east India, Calcutta, p.52
  11. ^ Turkish Studies Association Bulletin, 1982, Volume 6, p.79
  12. ^ Potapov L.P., 1969, "Ethnic Composition and Origin of Altaians," Science, Leningrad, pp.44 on
  13. ^ UNESCO, 1977, Effects of the growth of human activities on the Taï forest of the south-west of the Ivory coast, http://unesco.org/images/0003/000309/030983eb.pdf
  14. ^ Fainberg L., 1967, 'On the Question of the Eskimo kinship system,' Arctic Anthropology, Vol. 4, No. 1, p.244 on
  15. ^ Golovnev A.V., "From One to Seven: Numerical Symbolism in Khanty Culture," Arctic Anthropology, Vol. 31, No. 1, pp.62-71
  16. ^ Jackson, Jean E. 1983. The Fish People - Linguistic Exogamy and Tukanoan Identity in Northwest Amazonia. Cambridge University Press.

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