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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Aboriginal Americans: Heterochronic Patterns


"Both of these analyses of L-R differences found the Maya considerably less biased to the right hand than the Ladinos, and in both cases the English bias in intermediate. In comparison with my English samples, the Ladinos show a stronger right shift, and the Maya a slightly lesser right shift. These differences concern the L-R differences between the hands in skill, which are presumed to underlie observed perferences. So far in this book, it has been assumed that differences between racial groups in hand preferences for writing and other skilled actions are due to cultural pressures that affect the threshold at which sinistraity is manifested. If the present observations for differing z scores on measures of skill are confirmed in further research, the possibility must be considered that there are racial differences in right shift. Racial differences could occur either because there were differences in the frequency of the rs + gene or because there were differences in the expressivity of the gene. Differences in expressivity have been postulated between the sexes and between twins and the singleborn, and these have been tentatively attributed to differences in relative growth and/or maturity at birth. Cross-cultural studies of neonatal maturity and development in infancy have reported several differences between racial groups, but the evidence is insufficient to reach any firm conclusions about the relative rates of maturation of Landinos and Mayan children (Super, 1981). Assuming a lesser right shift is associated with lesser maturity at birth (as postulated for males and twins), the Maya would be expected to be slightly less mature than Landinos. Studies of Maya Indians in Mexico (Brazelton, Robey, & Collier, 1969) and of Hopi Indians in the United States (Dennis, 1940) both concluded that development in infancy paralleled that of Caucasian children but was approximately 1 month delayed; this delay was found in the latter sample that could be relevant to the expression of the rs + gene. The newborn observed were very small (about 5 lbs.), though not premature. On tests of development, items concerning quality of vocalisation could not be scored because of the paucity of social babbling. The main aim of the mothers seemed to be to keep the infants quiet, but it seems remarkable that the voice play that is so evident in Caucasian children in the second half of the first year should be so reduced." (Annett, Marian (1985) Left, Right, Hand and Brain: The Right Shift Theory London: Lawrence Erlbaum pp. 394)

“...both male and female Indian subjects had lower metabolic rates per unit weight than had Europeans. The differences were not small - about 10%. The data used to establish this racial difference are the results of numerous investigations conducted many years ago. Recent work (Shetty 1984) shows that poor Indian labourers do indeed have a basal metabolism which is 17% less than the FAO/WHO/UNO standards, and other studies (McNeill et al. 1987) suggest a lowering by 12%. Whether the low basal metabolism in Indians is a true racial characteristic, is due to climatic factors or is the result of depression of metabolism by long-term under-nutrition is not known.” (Blaxter K (1989) Energy metabolism in animals and man. Cambridge U. Press, Cambridge p. 144) [its not clear whether they mean American or India Indian]

"A surprising left-ear dichotic listening superiority was reported for a group of native Navajo college students (Scott, Hynd, Hunt, & Weed. 1979)" (Annett, Marian (1985) Left, Right, Hand and Brain: The Right Shift Theory London: Lawrence Erlbaum pp. 394)

"Faster times for left-handers were found in Maya and in Landinos children, as in English children. Thus the assumptions basic to the balanced polymorphism hypothesis, that the bias to the right hand gives advantages to language learning but at the cost of actual hand speed, is supported by this independent cross-cultural study." (Annett, Marian (1985) Left, Right, Hand and Brain: The Right Shift Theory London: Lawrence Erlbaum pp. 396)

"Dawson (1972, 1974) has pointed out that hunting and fishing cultures, such as Eskimo and Australian Aborigine peoples, tend to show higher rates of left-handedness than agricultural communities, such as the Temne and the Chinese Hakka, and he suggested that this may be accounted for by the emphasis on independent values and the relatively low degree of conformity found in nomadic groups." (Bishop, D.V.M. (1990) Handedness and Developmental Disorder. MacKeith, Manchester pp. 13)

"The highest proportion of left-handedness that I could discover from a reliable source was for the Kwakiutl Indians of British Columbia, 17 to 22 per cent of whom were left-handed or ambidextrous for writing (Marrion 1886). [fornote says 'Marrian reported that no fewer than 6 per cent of Kwakiutl Indians could write with either hand. However, there is no tradition of written languge in this culture, and many adults do not write after leaving school. Marrion (personal communication) noted that many treated writing their name as an activity akin to drawing.'" (Bishop, D.V.M. (1990) Handedness and Developmental Disorder. MacKeith, Manchester pp. 12)

"Amongst the various Amerindian populations (Figs 91 and 92) there is a wide variation in height means. North American Indians are taller and heavier than South American and Central American Indians. The Blackfeet means are well up in the European range, as are the means for British Columbian Indians (Birkbeck, Lee, Meyers & Alfred, 1971; Lee et al., 1971; not plotted). The Apache Indian and Alaskan Eskimo children are also considerably taller at all ages than the South and Central Americans. Even though they do have many traits in common, North American and South American Indians differ considerably in physique and craniofacial structure." (Eveleth, P.B. & Tanner, J.M. (1976) Worldwide Variation in Human Growth: Cambridge Univ. Press, London p. 127)

"The greatest retardation in the populations considered here is found among the highland Quechua Amerindians. Delays of 14% to 58% (according to centre) in boys, and 11% to 91% in girls have been reported for the early childhood ossification centres. ... The comparisons discussed above, together with the older results (summarised in Tanner, 1962, p. 62), show that African children under good nutritional and environental circumstances are more advanced than Europeans in skeletal development from birth to adolescence. There are no data showing whether the advancement continues into adolescence, though it seems probable. Quite a different picture emerges for Asiatics, represented by Chinese and Japanese. Although similar during childhood to Europeans they become advanced at adolescence." (Eveleth, P.B. & Tanner, J.M. (1976) Worldwide Variation in Human Growth: Cambridge Univ. Press, London p. 206)

"The rate of premarital intercourse is matched by that following marriage. We inspected a section on cross-cultural intercourse frequency in a review by Ford and Beach (1951) and categorized the tribal peoples listed into three main groups. The Oceanic and Amerindian peoples tended to a lower per week average (1-4), than U.S. whites (2-4), than Africans (3-10). Recent surveys support the same conclusion. For married couples in their 20's, the average frequency per week of intercourse for the Japanese approximates 2 (Asayama, 1975), for American whites 4, and for American blacks, 5 (Fisher, 1980)." (Rushton, J.P. & Bogaert, A.F. (1987) Race differences in sexual behavior: Testing an evolutionary hypothesis. Journal Research in Personality 21(4): pp. 535)

"Thirty pairs of dichotically presented CV syllables were administered to matched samples of Native American Navajo and Anglo subjects. While sex was not a significant factor, significant differences were evidenced in the performance of the Native American Navajo and Anglo subjects. As predicted, the Navajo subjects demonstated a left ear advantage compared to the traditional right ear effect found in the Anglo subjects. These results are discussed as they relate to linguistic processing and neuropsychological theory. ... Cllinical reports of aphasic Japanese subjects have shown them to have considerable variability in their writing of Kana and Kanji characters (6-9). The Kana symbols are phonetic representations of syllables, while the Kanji characters represent the legographic properties of the characters. Recent studies have investigated the capacity of the two cerebral hemispheres in normal Japanese subjects to differentiate and process these two types of written characters {10-12}. The results of these studies have indicated that the two cerebral hemispheres do differentially process Kana and Kanji characters. The Kana (phonetic) symbols seem to be processed in the left cerebral cortex while the Kanji (logograhic) characters are more reliably reported when projected to the right cerebral hemisphere. These results seem to be consistent whth the clinical observations noted in aphasic Japanese patients {6-9} and are intriquing for several reasons. First, reading these symbols in Japanese appears to require a more neurologically integrated effort than reading English, as it seems to involve the processing of symbols in both cerebral hemispheres rather than in the left cerebral cortex, which seems to be the case with English. Second, one could speculate that some mechanism must scan the characters and, based on their stimulus properties, shift attention transcallosally to the appropriate hemisphere. Finally, these studies suggest that cerebral function for written Japanese may be less fully lateralized in Japanese subjects as is traditionally reported in the contempory literature for English-speaking subjects. If this is indeed the case, there may be other populations in which language lateralization differs relative to our current understanding of neuropsychological asymmetries. There is some very limited evidence that lateralization for language in the Native American Hopi differs more dramatically than would be expected {13}. Using an analysis of EEG ratios, these investigators found a significant right cerebral hemisphere specialization for language processing in Hopi Indian children." (Scott, S., Hynd, G.W., Hunt, L. & Weed, W. (1979) Cerebral speech lateralization in the American Navajo. Neuropsychologia 17: 89)


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