Inbreeding, Incest, and the Incest Taboo: The State of Knowledge at the Turn of the Century
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That there is a biological basis for the avoidance of inbreeding seems incontrovertible, but just how injurious inbreeding really is for successive generations remains an open question. Nor has there been any conclusion to the debate over Freud’s view that the incest taboo is necessary because humans are sexually attracted to their closest relatives—a claim countered by Westermarck's argument for the sexually inhibiting effects of early childhood association.
This book brings together contributions from the fields of genetics, behavioral biology, primatology, biological and social anthropology, philosophy, and psychiatry which reexamine these questions.
such a mechanism a reduced preference for those individuals that are very familiar. Two well-known learning processes, behavioral imprinting and long-term habituation, are able to generate a preference for individuals who are a bit different but not too different from those individuals who are familiar from early life.28 If, as the evidence strongly suggests, inbreeding and excessive outbreeding carry biological costs in the form of reduced reproductive success, then the activation of both
not yet resumed sexual cycles. (a) 0.20 Proportion of Mother’s Copulations 0.15 0.10 0.05 0.00 1 10 20 30 20 30 Male Age (b) 0.20 Proportion of Sister’s Copulations 0.15 0.10 0.05 0.00 1 10 Male Age figure 3.1. Copulations Between Mothers and Sons and Sisters and Brothers in the Gombe Chimpanzees. (a) Mean (SE) proportion of mothers’ copulations contributed by sons of each age (N = 25 mother-son pairs, with some pairs observed over several years). (b) Mean (SE) proportion
a factor? Girls adopted as infants were most often matched with a boy born two or three years previously, but many were matched with boys born six or seven years previously and others with boys born after their arrival. Might it be, then, that we need to attend to the husband’s age at first association as well as the wife’s? It all depends on whether Dr. Ellis was right. If the “instinct” was really “more marked in the female” than in the male, it might not matter very much how old a boy was when
redress the balance by analyz- 94 scheidel ing the available data within a biosocial framework. Rather than guessing at possible explanations, I have focused on the probable repercussions of and constraints on this peculiar custom, drawing on comparative evidence for inbreeding depression and avoidance behavior.5 As a result, Roman Egyptian sibling marriage has now finally entered the debate on the biological basis of human incest taboos.6 It is easy to show that the most intensely incestuous
similarities between self and others. Biologists call this “phenotypic matching.”81 Many species, including humans, quickly learn to identify familial characteristics; at birth, mothers typically adopt an en face orientation for close inspection of their infant. Within a very short time, they can reliably identify their offspring through visual, auditory, olfactory, or tactile cues.82 Similarly, fathers appear to have a remarkable ability to identify offspring soon after birth. With an average of