View source for Incest taboo

{{short description|Cultural rule that prohibits incest}}
{{Anthropology of kinship |concepts}}

An '''incest taboo ''' is any [[Convention (norm)|cultural rule]] or [[Norm (social)|norm]] that prohibits [[Human sexual activity|sexual relations]] between certain members of the same [[family]], mainly between individuals [[Consanguinity|related by blood]]. [[Cultural universal|All known human cultures]] have norms that exclude certain close relatives from those considered suitable or permissible [[Sexual partner|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 [[Incest|incestuous relationship]]s.

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 [[elite]]s with some regularity. Parent–child and sibling–sibling unions are almost universally taboo.<ref>''The Tapestry of Culture An Introduction to Cultural Anthropology'', Ninth Edition, Abraham Rosman, Paula G. Rubel, Maxine Weisgrau, 2009, AltaMira Press. {{ISBN|9780759111394}}. p.101</ref>

==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.<ref name=WolfDurham2005>''Inbreeding, Incest, and the Incest Taboo: The State of Knowledge at the Turn of the Century'', Arthur P. Wolf and William H. Durham (Editors),  Stanford University Press, 2004, {{ISBN|978-0804751414}}. Introduction</ref>

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 [[Alliance theory|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.{{Citation needed|date=February 2012}}

===Limits to biological evolution of taboo===
While it is theoretically possible that [[natural selection]] may, under certain [[genetics|genetic]] circumstances, select for individuals that [[instinct]]ively avoid mating with (close) relatives, incest will still exist in the gene pool because even genetically weakened, [[inbreeding|inbred]] individuals are better watchposts against [[predator]]s 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.<ref>E. O. Wilson, Consilience: The Unity of Knowledge, New York, Knopf, 1998</ref><ref>The Blind Watchmaker: Why the Evidence of Evolution Reveals a Universe without Design, Richard Dawkins, 1986</ref>{{Dubious|date=April 2020}} 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]].<ref>Gorrell J.C., McAdam A.G., Coltman D.W., Humphries M.M., Boutin S., Jamieson C.; McAdam, Andrew G.; Coltman, David W.; Humphries, Murray M.; Boutin, Stan (June 2010). "Adopting kin enhances inclusive fitness in asocial red squirrels". Nature Communications 1</ref><ref>Wright, Sewall (1922). "Coefficients of inbreeding and relationship". American Naturalist 56</ref>

==Research==
{{more citations needed section|date=February 2016}}

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.<ref>Marvin Harris 1997 ''Culture, People and Nature: An Introduction to General Anthropology'' 7th edition Longman pp. 250, 253</ref> 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:

{{quote|''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 (law)|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 ensue automatically by the action of a 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?<ref>A Committee of the Royal Anthropological Institute of Great Britain and Ireland, 1951. ''Notes and Queries on Anthropology'', 6th edition. London: Routledge and Kegan Paul, Ltd. p. 113–114</ref>}}

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.<ref name="WolfDurham2005" /> 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.

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 breastfeeding.<ref>Briggs, Jean Louise ''Never in anger: portrait of an Eskimo family'' 1970 Harvard University Press, Cambridge (Mass.)</ref><ref>Gregory Bateson, ''Steps to an ecology of mind: collected essays in anthropology, psychiatry, evolution, and epistemology'' preface by Mark Engel 1972 Chandler, San Francisco 112–115</ref>

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.{{Citation needed|date=November 2024}}

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,<ref>Bronislow Malinowski 1929 ''The Sexual Life of Savages in North-West Melanesia: An Ethnographic Account of Courtship, Marriage and Family Life Among the Natives of the Trobriand Highlands, British New Guinea'' Boston: Beacon Press 389, 392</ref> and between a woman and her father,<ref name=Malinowski29>Bronislaw Malinowski 1929 ''The Sexual Life of Savages in North-West Melanesia: An Ethnographic Account of Courtship, Marriage and Family Life Among the Natives of the Trobriand Highlands, British New Guinea'' Boston: Beacon Press 384</ref> 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.<ref name=Malinowski29/> 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.<ref>Bronislaw Malinowski 1929 ''The Sexual Life of Savages in North-West Melanesia: An Ethnographic Account of Courtship, Marriage and Family Life Among the Natives of the Trobriand Highlands, British New Guinea'' Boston: Beacon Press 450–451</ref>  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.<ref>Bronislaw Malinowski 1929 ''The Sexual Life of Savages in North-West Melanesia: An Ethnographic Account of Courtship, Marriage and Family Life Among the Natives of the Trobriand Highlands, British New Guinea'' Boston: Beacon Press 449–450</ref>

===Instinctual and genetic explanations===
{{seealso|Inbreeding depression}}
An explanation for the taboo is that it is due to an instinctual, inborn aversion that would lower the adverse [[Heredity|genetic effects]] of [[inbreeding]] such as a higher incidence of congenital [[birth defect]]s. Since the rise of modern genetics, belief in this theory has grown.<ref>Alexander, Richard 1977 "Natural Selection and the Analyusis of Human Sociology" in ''The Changing Scenes in the Natural Sciences, 1776–1976'' pp. 283–337 Academy of Natural Science Special Publication 12</ref><ref>{{cite journal | last1 = Bittles | display-authors = etal  | year = 1991 | title = Reproductive Behavior and Health in Consangueneous Marriages | journal = Science | volume = 2 | issue = 52| pages = 789–794 | doi = 10.1126/science.2028254 | pmid = 2028254 | bibcode = 1991Sci...252..789B | s2cid = 1352617 }}</ref><ref name="doi10.1038/ng1094-117">{{Cite journal | last1 = Bittles | first1 = A. H. | last2 = Neel | first2 = J. V. | doi = 10.1038/ng1094-117 | title = The costs of human inbreeding and their implications for variations at the DNA level | journal = Nature Genetics | volume = 8 | issue = 2 | pages = 117–121 | year = 1994 | pmid =  7842008| s2cid = 36077657 }}</ref><ref name=moral>{{Cite journal | last1 = Lieberman | first1 = D. | last2 = Tooby | first2 = J. | last3 = Cosmides | first3 = L. | doi = 10.1098/rspb.2002.2290 | title = Does morality have a biological basis? An empirical test of the factors governing moral sentiments relating to incest | journal = Proceedings of the Royal Society B: Biological Sciences | volume = 270 | issue = 1517 | pages = 819–826 | year = 2003 | pmid =  12737660| pmc = 1691313}}</ref>{{failed verification|date=November 2011}}

====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.<ref>{{cite journal | last1 = Livingstone | first1 = Frank B | year = 1969 | title = Genetics, Ecology, and the Origins of Incest and Exogamy | journal = Current Anthropology | volume = 10 | pages = 45–62 | doi=10.1086/201009| s2cid = 84009643 }}</ref> 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.<ref>Thornhill, Nancy, ed. 1993 ''The Natural History of Inbreeding and Outbreeding''. Chicago: UNiversity of Chicago Press</ref> Besides recessive genes, there are also other reasons why inbreeding may be harmful, such as a narrow range of certain [[immune system]]s 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.<ref>{{cite journal |last1=Antfolk |first1=Jan |last2=Lieberman |first2=Debra |last3=Santtila |first3=Pekka |title=Fitness Costs Predict Inbreeding Aversion Irrespective of Self-Involvement: Support for Hypotheses Derived from Evolutionary Theory |journal=PLOS ONE |date=2012 |volume=7 |issue=11|doi=10.1371/journal.pone.0050613 |article-number=e50613 |pmid=23209792 |pmc=3509093|bibcode=2012PLoSO...750613A |doi-access=free }}</ref> Children born of close relatives have decreased survival.<ref name="doi10.1038/ng1094-117"/><ref name="moral"/> Many mammal species, including humanity's closest [[primate]] relatives, avoid incest.<ref name="WolfDurham2005"/>

====Westermarck effect====
{{main|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.<ref>Westermarck, Edvard A. (1921). ''The history of human marriage'', 5th edn. London: Macmillan</ref> [[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.<ref>Spiro, M. (1965). Children of the Kibbutz. New York: Schocken.</ref> 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.<ref>{{Cite journal | last1 = Shepher | first1 = J. | title = Mate selection among second generation kibbutz adolescents and adults: Incest avoidance and negative imprinting | doi = 10.1007/BF01638058 | journal = Archives of Sexual Behavior | volume = 1 | issue = 4 | pages = 293–307 | year = 1971 | pmid =  24179077| s2cid = 25602623 }}</ref>

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.<ref>{{cite journal | last1 = Hartung | first1 = John | year = 1985 | title = Review of ''Incest: A Biological View'' by J. Shepher | doi = 10.1002/ajpa.1330670213 | journal = American Journal of Physical Anthropology | volume = 67 | pages = 167–171 }}</ref>

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.<ref>Wolf, A. 1995. ''Sexual attraction and childhood association: a Chinese brief for Edward Westermarck''. Stanford, CA: Stanford University Press.</ref>

====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.<ref name=moral/> Humans have been argued to have a special kin detection system that besides the incest taboo also regulates a tendency towards [[altruism]] towards kin.<ref>{{Cite journal | last1 = Lieberman | first1 = D. | last2 = Tooby | first2 = J. | last3 = Cosmides | first3 = L. | doi = 10.1038/nature05510 | title = The architecture of human kin detection | journal = Nature | volume = 445 | issue = 7129 | pages = 727–731 | year = 2007 | pmid =  17301784| pmc = 3581061| bibcode = 2007Natur.445..727L }}</ref>

====Counter arguments====
One objection against an instinctive and genetic basis for the incest taboo is that incest does occur.<ref>Claude Lévi-Strauss, 1969 ''The Elementary Structures of Kinship'' revised edition, translated from the French by James Harle Bell and John Richard von Sturmer. Boston: Beacon Press. 17</ref><ref>Cicchetti and Carlson eds. 1989 ''Child Maltreatment: Theory and Research on the Causes and Consequences of Child Abuse and Neglect''. New York, Cambridge University Press</ref><ref>Glaser and Frosh 1988 ''Child and Sexual Abuse'' Chicago: Dorsey Press.</ref> 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.<ref>Claude Lévi-Strauss, 1969 ''The Elementary Structures of Kinship'' revised edition, translated from the French by James Harle Bell and John Richard von Sturmer. Boston: Beacon Press. 13–14</ref> Other studies on cousin marriages have found support for a biological basis for the taboo.<ref>{{Cite journal | last1 = Kushnick | first1 = G. | last2 = Fessler | first2 = D. M. T. | doi = 10.1086/659337 | title = Karo Batak Cousin Marriage, Cosocialization, and the Westermarck Hypothesis | journal = Current Anthropology | volume = 52 | issue = 3 | pages = 443–448 | year = 2011 | url = https://openresearch-repository.anu.edu.au/bitstream/1885/50038/2/01_Kushnick_Karo_Batak_Cousin_Marriage%2c_2011.pdf | hdl = 1885/50038 | s2cid = 20905611 | hdl-access = free }}</ref><ref>{{Cite journal | last1 = Fessler | first1 = D. M. T. | title = Neglected Natural Experiments Germane to the Westermarck Hypothesis | doi = 10.1007/s12110-007-9021-1 | journal = Human Nature | volume = 18 | issue = 4 | pages = 355–364 | year = 2007| pmid = 26181312 | s2cid = 2039872 }}</ref><ref>{{Cite journal | last1 = McCabe | first1 = J. | doi = 10.1525/aa.1983.85.1.02a00030 | title = FBD Marriage: Further Support for the Westermarck Hypothesis of the Incest Taboo | journal = American Anthropologist | volume = 85 | pages = 50–69 | year = 1983| doi-access =  }}</ref> 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).<ref name=AmPs2010>{{Cite journal | last1 = Confer | first1 = J. C. | last2 = Easton | first2 = J. A. | last3 = Fleischman | first3 = D. S. | last4 = Goetz | first4 = C. D. | last5 = Lewis | first5 = D. M. G. | last6 = Perilloux | first6 = C. | last7 = Buss | first7 = D. M. | doi = 10.1037/a0018413 | title = Evolutionary psychology: Controversies, questions, prospects, and limitations | journal = American Psychologist | volume = 65 | issue = 2 | pages = 110–126 | year = 2010 | pmid = 20141266 | url = http://homepage.psy.utexas.edu/homepage/Group/BussLAB/pdffiles/evolutionary_psychology_AP_2010.pdf | access-date = 2015-08-28 | archive-date = 2015-08-20 | archive-url = https://web.archive.org/web/20150820063400/http://homepage.psy.utexas.edu/homepage/Group/BussLAB/pdffiles/evolutionary_psychology_AP_2010.pdf }}</ref>

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).<ref>Stewart-Williams, Steve. The ape that understood the universe: How the mind and culture evolve. Cambridge University Press, 2018, pp 135-136</ref>

===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.<ref name=WolfDurham2005/>

====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 (Mauss book)|The Gift]]'', which (in Lévi-Strauss' words) argued:

{{quote|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.<ref>Claude Lévi-Strauss, 1969 ''The Elementary Structures of Kinship'' revised edition, translated from the French by James Harle Bell and John Richard von Sturmer. Boston: Beacon Press. 52</ref>}}

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:

{{quote|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, whom will you visit?<ref>Claude Lévi-Strauss, 1969  ''The Elementary Structures of Kinship'' revised edition, translated from the French by James Harle Bell and John Richard von Sturmer. Boston: Beacon Press. 485</ref>}}

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.<ref>Claude Lévi-Strauss, 1969 ''The Elementary Structures of Kinship'' revised edition, translated from the French by James Harle Bell and John Richard von Sturmer. Boston: Beacon Press. 492-496</ref> 

Some anthropologists argue that nuclear family incest avoidance can be explained in terms of the ecological, demographic, and economic benefits of exogamy.<ref>{{cite journal | last1 = Leavitt | first1 = Gregory | year = 1989 | title = Disappearance of the Incest Taboo | journal = American Anthropologist | volume = 91 | pages = 116–131 | doi=10.1525/aa.1989.91.1.02a00070}}</ref>

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.<ref>Spencer, Paul. 1988. ''The Maasai of Matapato: a Study of Rituals of Rebellion'', Manchester University Press, Manchester.</ref>

====Endogamy====
Exogamy between households or descent groups is typically prescribed in [[Classless society|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 [[Caste_system_in_India|India's caste system]], in which unequal castes are endogamous.<ref>Marvin Harris 1997 ''Culture, People and Nature: An Introduction to General Anthropology'' 7th edition Longman pp. 250, 311</ref> Inequality between [[ethnic group]]s and [[Race (classification of humans)|races]] also correlates with endogamy.<ref>Marvin Harris 1997 ''Culture, People and Nature: An Introduction to General Anthropology'' 7th edition Longman pp. 317–318</ref>

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.<ref>{{cite journal | last1 = Bixler | first1 = Ray | year = 1982 | title = Comment on the Incidence and Purpose of Royal Sibling Incest | journal = American Ethnologist | volume = 9 | issue = 3| pages = 580–582 | doi=10.1525/ae.1982.9.3.02a00100}}</ref> Some scholars have argued that in Roman-governed Egypt this practice was also found among commoners,<ref>{{cite book |last1=Frier |first1=Bruce W. |last2=Bagnall |first2=Roger S. |author2-link=Roger S. Bagnall |title=The Demography of Roman Egypt |publisher= [[Cambridge University Press]] |location=Cambridge, UK |year=1994 |isbn=0-521-46123-5}}</ref><ref>{{cite journal | last = Shaw | first = B. D. | title = Explaining Incest: Brother-Sister Marriage in Graeco-Roman Egypt | journal = Man |series=New Series | volume = 27 | issue = 2 | year = 1992 | pages = 267–299 | jstor=2804054 | doi=10.2307/2804054}}</ref><ref>{{cite journal | last = Hopkins | first = Keith | author-link = Keith Hopkins | year = 1980 | title = Brother-Sister Marriage in Roman Egypt | url = http://humweb.ucsc.edu/jklynn/ancientwomen/HopkinsBrotherSisterMarriage.pdf | journal = Comparative Studies in Society and History | volume = 22 | pages = 303–354 | doi = 10.1017/S0010417500009385 | issue = 3 | s2cid = 143698328 | access-date = 2013-07-21 | archive-date = 2016-03-03 | archive-url = https://web.archive.org/web/20160303180202/http://humweb.ucsc.edu/jklynn/ancientwomen/HopkinsBrotherSisterMarriage.pdf }}</ref><ref>{{cite journal | last = Scheidel | first = W | title = Brother-sister marriage in Roman Egypt | journal = Journal of Biosocial Science | year = 1997 | volume = 29 | issue = 3 | pages = 361–71 | doi = 10.1017/s0021932097003611 | pmid = 9881142 | s2cid = 23732024 | url = http://humweb.ucsc.edu/jklynn/AncientWomen/ScheidelBrotherSisterMarriages.pdf | access-date = 2013-03-08 | archive-date = 2013-11-02 | archive-url = https://web.archive.org/web/20131102012940/http://humweb.ucsc.edu/jklynn/AncientWomen/ScheidelBrotherSisterMarriages.pdf }}</ref> but others have argued that this was in fact not the norm.<ref>Walter Scheidel. 2004. "Ancient Egyptian Sibling Marriage and the Westermarck Effect", in ''Inbreeding, Incest, and the Incest Taboo: the state of knowledge at the turn of the century'' Arthur Wolf and William Durham (eds) Stanford University Press. pp. 93-108</ref><ref>[[Sabine R. Huebner|Huebner, Sabine R.]] "'Brother-Sister' Marriage in Roman Egypt: a Curiosity of Humankind or a Widespread Family Strategy?." The Journal of Roman Studies 97 (2007): 21-49.</ref><ref>Huebner, Sabine R. The family in Roman Egypt: a comparative approach to intergenerational solidarity and conflict. Cambridge University Press, 2013, pp.190-195</ref>

==See also==
* [[Baldwin effect]]
* [[Cinderella effect]]
* [[Heterosis]]
* [[Homozygosity]]
* [[Inbreeding avoidance]]

==References==
{{reflist}}

==Bibliography==
* Claude Lévi-Strauss, 1969 ''The Elementary Structures of Kinship'' revised edition, translated from the French by James Harle Bell and John Richard von Sturmer. Boston: Beacon Press
* [[George Homans]] and [[David M. Schneider]], ''Marriage, Authority, and Final Causes: A Study of Unilateral Cross-Cousin Marriage''
* [[Rodney Needham]], ''Structure and Sentiment: A Test Case in Social Anthropology''
* Arthur P. Wolf and William H. Durham (editors), ''Inbreeding, Incest, and the Incest Taboo: The State of Knowledge at the Turn of the Century'', {{ISBN|0-8047-5141-2}}

{{Incest}}
{{Evolutionary psychology}}

[[Category:Incest|Taboo]]
[[Category:Sociobiology]]
[[Category:Interpersonal relationships]]
[[Category:Kinship and descent]]
[[Category:Taboo]]