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Avoidance and prohibition of brother–sister sex in humans
Author(s) -
Aoki Kenichi
Publication year - 2005
Publication title -
population ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 59
eISSN - 1438-390X
pISSN - 1438-3896
DOI - 10.1007/s10144-004-0199-3
Subject(s) - brother , biology , taboo , sister , inclusive fitness , argument (complex analysis) , mechanism (biology) , adaptation (eye) , mating , punishment (psychology) , evolutionary biology , zoology , social psychology , psychology , law , epistemology , neuroscience , biochemistry , philosophy , political science
Sex between full sibs is unusual in birds, mammals, and humans. These species likely possess an innate avoidance mechanism based on early proximity (i.e., the Westermarck hypothesis), and the “rare” occurrences may be attributable to error. Alternatively, an inclusive fitness argument shows that a low rate of sib mating may be an “adaptation.” The widespread occurrence of a prohibition against brother–sister sex in human societies is often invoked as evidence against an innate avoidance mechanism, since if the latter were to exist the former would be superfluous. However, given that punishing violators is costly, a prohibition is more likely to spread through an egalitarian society when the prohibited behavior is already avoided. I describe a model of the cultural dynamics of the sibling incest taboo which we have used to investigate this possibility. The predictions derived from this model are consistent with, and add rigor to, Westermarck's theory of the origin of the incest taboo.