© 2003, 2009 Walter Scheidel
BROTHER-SISTER AND PARENT-CHILD MARRIAGE
IN PRE-MODERN SOCIETIES
‘Incest’, in the sense of
proscribed and abhorred sexual behaviour, is a cultural construct; its
boundaries vary according to definitions that are specific to individual
cultures (e.g., Willner 1983). However, most cultures agree on the core of what
constitutes incest: sexual relations within the nuclear family. This perception
corresponds to the biological fact that on average, parents and children on the
one hand and brothers and sisters on the other share fifty per cent of their
genes by common descent, and are therefore much more closely related than other
potential mates. Over the last century, the ubiquity of the incest taboo for
the nuclear family and resultant avoidance behaviour have been explained in
several different and sometimes conflicting ways. Freudian theory has it that
although by nature, children harbour incestuous longings, in the absence of
legitimate expression these desires are suppressed into the subconscious,
triggering abhorrence in adult life; the ‘family-socialization theory’ explains
the incest taboo in terms of its functions in maintaining the social structure
of the human family and in facilitating the process of socialization (e.g.,
Malinowski, Murdock, Parsons); anthropologists have argued that the need of
families to exchange wives and resources in order to forge alliances militates
against incestuous unions (e.g., Tylor, White, Lévi-Strauss); the ‘demographic
theory’ predicts that under high mortality, siblings were compelled to find
mates outside their own families. Critiques of existing views and further
alternative theories continue to be published (e.g., Ember 1983; Roscoe 1994).
According to the ‘indifference theory’, early childhood association results in
sexual indifference and aversion between siblings and between parents and
offspring; conversely, incestuous behaviour is often caused by the lack or
insufficient intensity of early contacts (first propounded by Westermarck 1891;
see now Shepher 1983 and Wolf 1995 for the fullest expositions). As a
consequence, sexually mature family members of one sex migrate, i.e., marry,
outside the nuclear family. Animal dispersal can be explained in the same
fashion (e.g., Pusey 1990). From a Darwinian perspective, natural selection
favoured the evolution of this instinctive preference in the first instance
because of the negative genetic effects of close inbreeding, and also because
of the evolutionary benefits of genetic variation (e.g., van den Berghe 1983;
Thornhill, ed. 1993). By way of a gene-culture co-evolutionary process,
cultural precepts tend to reinforce this behavioural pattern (
In reality, of course, tensions between this (supposedly innate) principle and extraneous exigencies impel compromises between inbreeding and outbreeding. With certain types of inbreeding, such as marriage of first cousins or of uncles and nieces, moderate health losses may be offset by social and economic gains (eg., Khlat 1989; Reddy 1993). Even in societies that condone close-kin unions at these levels, however, the taboo against marital relations within the nuclear family sex is usually upheld (Thornhill 1991; Bonte, ed. 1994), in keeping with the fact that the latter cause much greater damage to offspring than less close unions (esp. Seemanová 1971). This has led some distinguished researchers to declare this type of incest taboo a universal cultural constant (Murdock 1949) or to assume that it lay at the heart of human social evolution and civilization (Levi-Strauss 1969).
The spread and force of
incest avoidance make cases of socially and legally condoned marital and/or
sexual relations within the nuclear family all the more intriguing.
Paradoxically, they have been given short shrift in global surveys of incest
(Fox 1980; Arens 1983; Héritier 1994). In a number of pre-modern societies,
relations of this kind were the exclusive prerogative of kings and remained
forbidden to commoners. ‘Royal incest’ (Bixler 1982), which serves to emphasize
the supernatural qualities of the rulers (strongly associated with mythological
traditions of divine incest) and insulates ruling families against intrusions,
can be found around the globe, from the Pharaohs and Ptolemies of ancient Egypt
(e.g., Cerny 1954; Carney 1987) and ancient Near Eastern rulers (e.g., Elam,
Persia, Phoenicia, etc.) (Kornemann 1923) to kings in Central Africa (de Heusch
1958), the Inca of Peru and the Mixtec aristocracy of
The phenomenon of marriage
within the nuclear family has never received comprehensive treatment. Studies
of sibling marriage in Roman Egypt have failed to provide a compelling
explanation of this custom (Hopkins 1980; Shaw 1992) and have usually
considered this subject in separation from the cross-cultural record. Moreover,
the (biologically) incestuous nature of Roman Egyptian sibling marriage has
recently been called into question (Hübner 2007, with Remijsen and Clarysse
2008). This alone shows the need for comprehensive reconsideration. The
evidence of Zoroastrian incest has never even been collected in an exhaustive
manner, let alone properly analysed (Sidler 1971 and now Frandsen 2009 are the
best efforts). Comparative evaluations – between
Albeit primarily designed as an historical study, my project does not address an exotic and marginal phenomenon. As indicated above, nuclear-family incest has played a crucial rôle in influential theories of human behaviour and development throughout this century, such as psychoanalysis, structuralism, and sociobiology. Incest and its avoidance occupy prominent positions in competing approaches to the understanding of human social behaviour, for instance in nature/nurture debates. As a consequence, the phenomenon of historical incest is of interest to scholars in a wide range of different disciplines. This project offers a rare opportunity to advertise ancient history to a wider academic audience, and to meet the twofold objective of contributing to historical scholarship and of bridging institutional boundaries between different disciplines.
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