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.

 

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The Influence of Maturation Rates on Coloring: Hair and Eyes


"Eighty-three children with a severe hyperactive syndrome completed a questionaire which included the Handedness inventory of Oldfield. As can be seen in Table 1 [on wall] there was a preponderance of ?, most of them fair-haired and blue-eyed. All of the affected children had a history of atopic illnesses, and there was an elevated rate of left-handedness. Among the siblings of these children were eight cases of dyslexia and ? of autism. (Behan, P. & Geschwind, N. (1985) Dyslexia, congenital anomalies, and immune disorders: the role of the fetal environment. Annals of the New York Academy of Sciences 457: pp. 14)

"We do have data from Japan that are highly suggestive. Here, for many centuries, fair skins have been under parental control and, other things being equal, parents seek attractive brides for their sons. As elsewhere, members of the upper classes tend to be the luckiest. This might be expected to lead to selection as the generations have gone by. Research which I conducted a few years ago (Hulse 1967) indicated that this has taken place, for upper-class high school students have the fairest skins and those of the lower class the darkest, while middle-class students are intermdiate in pigmentation. Furthermore, data from Greece (Friedl 1962) indicate that girls who are considered good-looking marry earlier than, and need not be supplied with as large a dowry as, their less-attractive sisters. Throughout southern Europe, the upper classes contain a disproportionate number of blondes and near-blondes. Sexual preferences, though they may be based on social snobbery rather than aesthetic interest, are capable of shifting allele frequencies in human population." (Hulse, F.S. (1978) Group selection and sexual selection in human evolution. in Evolutionary models and studies (Hague) Meier, R., Otten, C.M., Abdel-Hameed, F. (eds.), Moulton Publisher, Paris. p. 33)

"We have found that blonds are significantly more nonrighthanded than brunettes (Schachter and Galabuda, in press). Thus, of 986 nonblonds 76% scored more than +70 on a modified Oldfield Handedness Battery (strongly righthanded), 12% scored in the 0 to +70 range (ambidextrous), and 12% scored in the 0-100 range (lefthanded). The corresponding figures for 131 blonds were 56%, 28%, and 16%; the difference in the distribution of scores in the two groups was highly significant." (Geschwind & Galaburda 1987: 162, Cerebral Lateralization)

"Another important pigmentary anomaly is early gray or white hair. It is frequently stated in the lay literature that early gray or white hair is common in the families of dyslexics. It has been our impression that in fact early gray hair is more common among individuals with anomalous dominance and their relatives, which would include those with childhood learning disorders. Early gray or white hair is of particular interest because of its known association with certain autoimmune diseases, the ones must often noted being pernicious anemia (Minot 1948) and autoimmune thyroid disorder (Wood 1983). In fact, we believe that it is even more widely associated with immune diseases. The association suggests immune attack on pigment cells in the hair follicles. Wood (1983) has confirmed the presence of a high rate of nonrighthandedness is patients with immune thyroid disease; he also found a high rate of early gray or white hair but did not report whether this was present more often in the lefthanded patients. An elevated rate of dyslexia was not found in the immune thyroid patients, but the series was probably too small to ascertain this point. Certain other features associated with early gray hair deserve mention. Early graying has important ethnic associations, being more common among northern Europeans and, we suspect, Blacks of West African descent but less common among southern Europeans and Far Eastern populations. This deserves further study, since it would be in keeping with the possibility tht anomalous dominance may be more common among northern Europeans and West Africans. In addition, the Japanese usually have sparse facial hair, and early baldness is less common among them than among northern Europeans. This suggests end-organ insensitivity or the hair follicles to dihydrotestosterone, but it is not clear whether this is related to the low prevalence of early gray of white hair. We have observed another striking feature of those early gray or white hair, namely, that affected males have a low rate of early male pattern baldness (which is very common in populations of northern European descent) and that affected females tend to show thinning of the hair much less often after the menopause. Male pattern baldness and postmenopausal hair thinning occur only in the presence of androgens. The male with early white or gray hair is not usually hypogonadal or insensitive to androgens. Diminished hair loss therefore suggests low local sensitivity of the hair follicles to androgens. As noted earlier, testosterone in many instances protects from immune attack. The converse may also be true: immune attack on the pigmented cells of the hair follicles may lead to reduced sensitivity to androgenic effects. One possibility, though a speculative one, is that antibodies binding to the hair follicles present a barrier to androgens. We have noted the lower rate of early male pattern baldness and sparse facial hair among the Japanese, resulting from insensitivity of the hair follicles to dihydrotestosterone. It would be interesting to know whether Europeans or Blacks with early gray hair also need to shave less frequently---that is, whether the immune protection against androgens also extends to facial hair......Korein (1981) reported that patients with dystonia or spasmodic torticollis displayed an elevated rate of blue or hazel eyes. Lang et al. (1982) disputed this, but Korein (1982) has pointed out that their data actually confirm his conclusions, a view with which we agree." (Geschwind & Galaburda 1987: 163-4, Cerebral Lateralization)

"Rats treated in early life with cortisone, even if from an albino strain, are typically small and dark, showing that steroids can lead to lifting of the repression of the melanin-producing enzymes, which is present in many forms of albinism. These cortisone-treated animals are immunologically different from others of the same strain. In Addison's disease, with its low rate of adrenal steroid production, the skin also becomes darker. In any case we believe that skin pigmentation and iris pigmentation both reflect immunological, and dominance characteristics." (Geschwind & Galaburda 1987: 165, Cerebral Lateralization)

"Harris concluded that only color (and only an orange-red color) made it possible for a cock lizard to recognize another territorial male." (MacLean 1990: 146, The Triune Brain in Evolution)

The red grouse are territorial and monogamous, the cock attentive to young. The black grouse gather in leks which a few males doing most of the mating. "The two species share the same food, habitat, and enemies..." (Ridley 1993: 188, The Red Queen)

"...fair skin allows the absorption of ultraviolet light to help stave off vitamin D deficiency. But the skin is not much fairer in blond than in dark swedes; truly fair skin goes with red hair, not blond." (Ridley 1993: 294, The Red Queen)

"Of the 50 subjects with learning disabilities, 10 (20%) were blond. In contrast, 121 of 1067 subjects without learning disabilities were blond (11%)... subjects with learning disabilities were nearly twice as likely to be blond compared with non-LD sujects.... These results raise the possibility that melanin may be involved both in the development of motor dominance and independently in the develoment of neural systems which, when maldeveloped, result in learning disabilities. (Schachter,Ransel & Geschwind (1987) Associations of Handedness with hair color and learning disabilities Neuropsychologia 25: pp. 275)

Children with Severe Hyperactive Syndrome had elevated lefthandedness, were largely blond and blue eyed, with cases of autism and dyslexia. (Behan, P. & Geschwind, N. (1985) Dyslexia, congenital anomalies, and immune disorders: the role of the fetal environment Annals of the New York Academy of Sciences 457: pp. 13-18)

"Morris (1985, p. 53) claims that "the male eye is very slightly bigger than the female, while the female eye shows a higher proportion of white than the male". This suggests that the male eye may have enlarged as an allometric correlate of larger body and head size, but the female eye white may have evolved through slightly more intense sexual selection through male mate choice. Across all human cultures, the eyes are used conspicuously in sexual flirtation, with the alternation between nervous eye contact and coy glancing-away being used to signal sexual interest (Eibl-Eibesfelt, 1989)." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 171)

"Behan et al. (1985) indicate that dyslexics have a high incidence of blue eyes and fair hair. Schachter et al. (1987), investigating a large sample of professionals, reported a borderline tendency for blondes to be more likely to report learning disabilities. They indicate that subjects with learning disabilities were almost twice as likely to be blonde as non-learning disabled subjects. Urion (1988) claims that those dyslexics whose families have a history of immune disorders also have a high frequency of premature greying." (Bryden MP, McManus IC, Bulman-Fleming, MB (1994) Evaluating the Empirical Support for the Geschwind-Behan-Balaburda Model of Cerebral Lateralization. Brain and Cognition 26: pp. 141)

"The examination of or more minutely classified data disclosed the fact that only one group of eyes (dark blue) and only one group of hair colour (light blond) showed a steady fall in percentage value over the period considered. Light blue eyes kept to a fairly steady percentage, and the class of all others, ranging from grey to brown, increased. ... If, then, the fundamental allelomorphs be protochrome and allochrome, it follows that the mutation which gave rise to the retention by the adult of blue eye and light blond hair is to be reckoned as a change leading to the retention of an infantile characteristic: it is paedomorphic, and therefore formally progressive. It is comparable in this respect with thickness of lip and hairlessness of body. It is possible that the mutation leading to the establishment of protochrome character took place in two stages." MacConaill MA, Ralphs FL (1936?) Post-natal development of hair and eye colour, with special reference to some ethnological problems. pp. 218-225)

"As I explained earlier, the northern dairying people lived in a mist-shrouded environment and had to bundle up against the cold most of the year. They were without access to vitamin D in fish and sea mammals, and lacked green leafy vegetables as an alternative source of calcium. Under these conditions, individuals who were genetically capable of digesting large quantities of unfermented milk were better able to maintain normal bone growth and avoid crippling bone diseases such as rickets and osteomalacia, and therefore enjoyed higher rates of reproductive success than individuals who obtained their calcium through fermented milk, yogurt, or cheese. Within 4,000 or 5,000 years, the gene that controls for lactose production in adulthood spread to over 90 percent of the individuals in northern European dairying populations." (Harris, Marvin (1989) Our Kind. Harper Perennial: New York p. 167)


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