Human evolution theory utilizing concepts of neoteny & female sexual selection
An etiology of neuropsychological disorders such as autism and dyslexia, and the origin of left handedness.
"Freud's rival in this field was Edward Westermarck; in 1891 he suggested that men do not mate with their mothers and sisters not because of social rules, but because they are simply not turned on by those they were reared with. Westermarck's idea was simple. Men and women cannot recognize their relatives as relatives, so they have no way of preventing inbreeding as such. (Curiously, quail are different, they can recognize their brothers and sisters even when reared apart.) But they can use a simple psychological rule that works ninety-nine times out of a hundred to avert an incestuous match. They can avoid mating with those whom they knew very well during childhood. Sexual aversion to one's closest relatives is thus achieved. True, this will not avert marriage between cousins, but then there is nothing much wrong with marriage between cousins: The chance of a recessive deleterious gene emerging from such a match is small, and the advantages of genetic alliance to preserve complexes of genes that are adapted to work with one another probably outweigh it. (Quial prefer to mate with first cousins rather than with strangers.) Westermarck did not know that, of course, but it strengthens hsi argument, for it suggests that the only incestuous relations a human being should avoid are the one between brother and sister, and parent and child." (Ridley 1993: 283, The Red Queen) [This preserves the genetic constellation of genes proven to work already in present environment vs. a stange environment with genes selected for that strange environment]
"But Westermarck's theory would also predict that if incest does occur, it will prove to be between parent and child, and specifically between father and daughter, because a father is past the age at which familiarity breeds aversion and because men usually initiate sex. That, or course, is the most common form in incest." (Ridley 1993: 284, The Red Queen)
"Bateson built an engenious device that exposed individual quail to five birds of the opposite sex, but of different degrees of relationship: a sibling nestmate, a sibling never seen before, a first cousin, a third cousin, and an unrelated bird. Both males and females generally preferred first cousins over all alternatives. ... Bateson therefore concludes, from this and other arguments, that quail may be following a highly abstract aethetic rule---prefer intermediary degrees of familiarity, not so close as to be cloying, not so distant as to be overly strange. If he is right, an elegant solution to the problem of avioding incest suggests itself. Quail are not Mendelian calculators. They are, rather, following a deeper, more abstract, rule of aesthetic preference that may be common to a wide range of animals and neurologies. Maximal attraction to intermediate familiarity will automatically exclude disadvantageous closest kin as potential mates.
(Gould 1993: 379-80, Eight Little Piggies)
"For males, the situation is totally different. They remain in their natal group, and since they cannot get pregnant, they do not risk anything by having six with relatives. It is the females in their group who stand to lose from such contact. We therefore assume inhibitions against sex with mothers and sisters. The way these inhibitions may come about is through early familiarity---the basic mechanism assumed to underlie incest-avoidance in a wide range of species, including our own. The principle is simple: individuals of the opposite sex with whom one has grown up since infancy fail to arouse sexual feelings. If this process is disrupted---as when zoos raise young apes in a nursery---sex between relatives is not that unusual. Without a common backround, there is no way of knowing, so to speak, to whom one might be related. Normally, however, early familiarity characterizes the relations of males with close female relatives, and keeps them from breeding." (De Wall & Lanting 1997: 117, Bonobo)
"After the age of two, young males increasingly pursue suxual relations with females, but virtually never with their own mothers. Having recorded only five instances in 137 mother-son units, Kano concludes that incest-avoidance is established at an early age. By the age of four or five, the sexual behavior of young males more and more resembles that of adult males. Swollen females often accommadate the desires of these little Don Juans, who solicit them in the species-typical manner with spread legs and erect penis. They already know how to achieve intromission is various positions." (De Wall & Lanting 1997: 117, Bonobo)
"The implications of these findings is that an individual is able to strike an optimal balance between inbreeding and outbreeding by learning about is immediate kin and mating with a member of the opposite sex that is slightly different from its immediate kin. What such a balance might amount to in practice has previously been uncertain. I report here that Japanese quail of both sexes, having been reared with their siblings, subsequently prefer a first cousin of the opposite sex. ( Bateson, P. (1982) Preferences for cousins in Japanese quail Nature 295: 236) [note: choice between sibling, sibling novel, 1st cousin novel, 3rd cousin novel, and non related novel stranger.]
"A study of 2,769 kibbutzim marriages found that only 13 occured between peers and that in each of them one mate had left the communal group before the age of six." (Fisher, H. (1992) Anatomy of Love: The Mysteries of Mating, Marriage, and Why We Stray. Simon & Schuster, New York, 1992. pp. 48)