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Library of Excerpts
Homosexuality and Neoteny; Are Homosexuals Maturationally Delayed? |
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"Although numerous researchers have hypothesized a biological factor in the etiology of homosexuality, there is a lack of empirical evidence. Previous investigations did not focus on behavioral functions of the brain. Using neuropsychological testing, we found an increased incidence of left-hand preference (defined as non-consistent right-hand preference) in a group of 32 homosexual women. A trend in the same direction was found in a group of 38 homosexual men. These results suggest that homosexual orientation has a neurobiological component possibly related to hemispheric functional asymmetry. The results are consistent with previous reports that (1) prenatal neuroendocrine events are a factor in the development of human sexual orientation and functional brain asymmetries, and (2) the mechanisms associated with homosexual orientation and related neuropsychological characteristics are different between the sexes, i.e. elevated levels of prenatal sex hormones in women and decreased levels in men." (McCormick CM, Witelson SF, Kingstone E (1990) Left-handedness in homosexual men and women. Neuroendocrine implications. Psychoneuroendocrinology 15: 69) "Sex hormone levels were found to be normal in the majority of homosexual women, but prenatal androgen excess, heterosexuality appears to be more frequent than bisexuality, an exclusive homosexuality is rare. ... Conversely, the removal of the adrenal, which is the major androgen-producing organ in the female, decreases labido (Waxenburg et al., 1959). These findings have led to the hypothesis that androgens are the libido hormone in women as well as in men (Money, 1961). ... We can conclude that the majority of female homosexuals appear to have testosterone and estogen levels within normal female range, whereas there seems to be a significant subgroup of about one-third of all subjects screened with an elevation of male sex hormone levels." (Meyer-Bahlburg, H. (1979) Sex hormones and female homosexuality: A critical examination. Archives of Sexual Behavior 8: 101-108) "Women exposed prenatally via their pregnant mothers to diethylstilbestrol (DES, a synthetic nonsteroidal estrogen with masculinizing effects in female mammals) received higher ratings of homosexual behavior (Ehrhardt et al., 1985) and showed an increased incidence of left-hand preference (Geschwind & Galaburda, 1985b) compared to female controls. Similarly, women with congenital adrenal hyperplasmia (CAH, an inherited condition which involves an excessive secretion of andrenal androgens) received higher ratings of homosexual behavior (Money et al., 1984; Money, 1987) and showed an increased incidence of left-hand preference (Nass et al., 1987) compared to female controls. In summary, there appears to be an association, at least in women, among excessive prenatal exposure to masculinizing hormones, homosexual behavior, and increased left-hand preference. The associations appear different for men. Among CAH men, who may have higher prenatal androgens, homosexual behavior was extremely rare (Money & Lewis, 1982, 1987; Money, 1987). Also, CAH men did not show increased left-hand preference compared to male siblings (Nass et al., 1987). Similarly, DES-exposed men showed no increase in homosexual behavior (Kester et al., 1980). In contrast, men with Klinefelter's syndrome (KS, 47XXY karyotype, a syndrome associated with reduced development of male secondary sex characteristics and possibly lower levels of prenatal androgens (Ratcliffe, 1976; Sorenson et al., 1981; Nielson et al., 1982)) showed a greater prevelance of left-hand preference than control males (Netley & Rovet, 1982; Braun, 1988). There does not appear to be a higher prevalence of homosexuality in KS men (Nielsen, 1969). However, given the lower libido of KS men (Nielsen, 1969; Raboch et al., 1979), comparisons of prevalence of atypical sexual behavior between KS men and normal men might not be appropriate. In sum, the available evidence suggests that, in contrast to women, higher exposure to masculinizing sex hormones in men is not associated with homosexual behavior and increased left-hand preference. It is open to question whether the latter two behavioral manifestations are associated with lower exposure to masculinizing hormones." (McCormick CM, Witelson SF, Kingstone E (1990) Left-handedness in homosexual men and women. Neuroendocrine implications. Psychoneuroendocrinology 15: 70-71) "The proportion of homosexual women who showed non-CRH (22/32, 69%) was significantly greater than that of the general population (35%) (z=3.55, p=0.0005, two-tailed). If the most common definition of hand preference was considered -- hand used for writing -- the female homosexuals showed only a trend toward greater left-hand preference (6/32, 19%) than in the general population (10%) (z=1.71, p=0,09, two-tailed). The proportion of homosexual men who showed non-CRH (17/38, 45%) was not statistically different from that of the general population (35%) (z=1.20, p=0.23, two-tailed). The male homosexuals showed a similar proportion of left-hand preference based on writing hand (4/38, 11%) as in the general population (10%)." (McCormick CM, Witelson SF, Kingstone E (1990) Left-handedness in homosexual men and women. Neuroendocrine implications. Psychoneuroendocrinology 15: 72) "For example, in the one neuropsychological study on lesbians reported to date, increased left handedness also was found, but the mechanism that is consistent with the literature is different than that for men: Increased levels of androgenic hormones appear associated with homosexuality and left-handedness in women (see McCormick et al., 1990, for discussion)." (Witelson SF (1991) Neural sexual mosaicism: Sexual differentiation of the human temporo-parietal region for functional asymmetry. Psychoneuroendocrinology 16: 147) "We found that homosexual men showed an increased prevalence of left handedness (nonCRH) compared to the general population (McCormick et al., 1987; 1990; McCormick & Witelson, 1991), and that among CRH men, homosexual men showed less functional asymmetry on a verbal dichotic listening test (McCormick & Witelson, 1990). We also observed lower spatial ability in homosexual than in heterosexual men (McCormick & Witselson, 1991). Based on these results, we suggested an association between sexual orientation and cerebral lateralization and , by inference, a neurological component to the etiology of sexual orientation. With repect to more general issues, these results suggest that early neuroendocrine events which may influence sexual orientation also may be factors in determining aspects of functional asymmetry and cognition." (Witelson SF (1991) Neural sexual mosaicism: Sexual differentiation of the human temporo-parietal region for functional asymmetry. Psychoneuroendocrinology 16: 146) "In this study five subjects in the HM group reported altered hand preference from left to right as the result of childhood training, whereas there was only one report of change from right to left, which suggest that later influences act ot reduce rather than increase any tendency to left-handedness in the homosexual population." (Lindesay, J. (1987) Laterality shifts in homosexual men. Neuropsychologia 25: 967) "Similarly, the fewer consistent right-handers among dysexics and homosexual males could be due to any factor which impeded the normal expression of the rs+ gene, probably as it influences cerebral maturation in late fetal or perinatal life. The effects of sex and twinning are not due, on the RS theory, to differences in genotype distribution, but rather to factors which modify gene expression during development. In dyslexics and homosexual men there could be differences in genotype (more rs - - genotypes perhaps) and / or developmental modifications of gene expression; there is no way of distinguishing these possibilities at present." (Annett, M. (1988) Comments on Lindesay: Laterality shift in homosexual men. Neuropsychologia 26 (2): pp. 343) "Yalom et al. (1973) studied 20 16-year old boys of diabetic mothers, who had received estrogen or progesterone during pregnancy. These boys showed less heterosexuality and less masculinity than 20 control boys. Netley and Rovet (1982) showed that among 33 males with 47,XXY syndrome, 24% were nonrighthanded, compared to 10% of a control group. ... In the present study, as well as in Lindesay (1987), only homosexual men were studied. In Rosenstein and Bigler (1987) and McCormick et al. (1990), both men and women were studied, and in the latter study, a significant increase in lefthandedness (or rather nonrighthandedness) was obtained for women. This was assumed to be related to higher-than-normal levels of prenatal testosterone levels. In their results, the increase in lefthandedness in homosexual women (which have lower occurrence than men in the general population) is much larger than that of homosexual men. It is, therefore, fair to assume that the increase in testosterone, believed to cause both lefthandedness and homosexuality in women, will give a more pronounced effect in women than in men." (Gotestam, K.O., Coates,T.J., Ekstrand, M. (1992) Handedness, dyslexia and twinning inhomosexual men. International Journal Neuroscience 63 (3-4): 184) "Left-handedness was assessed in a large sample of male homosexuals and male and female heterosexuals, some of whom had been tested for HIV infection, and others of whom had AIDS. No association was found between left-handedness and homosexuality, although there was a excess of left-handeds in subjects who have been tested for HIV infection (irrespective of whether the test was negative or positive). This result can be interpreted in three possible ways: as a response bias on the part of left-handers who were aware of the Geschwind hypothesis that left-handedness may confer a vulnerability to AIDS; as due to left-handedness being associated with AIDS infection and the incidence in AIDS patients being artefactually low due to an excess mortality in left-handed AIDS patients; and as left-handers showing both an increased vulnerability of HIV infection and a reduced likelihood of progression of HIV infection to AIDS. Our data are unable to distinguish betwen there hypotheses." (Marchant-Haycox SE, McManus IC, Wilson GD (1991) Left-handedness, homosexuality, HIV infection and aids. Cortex 27: 56) "In a larger study, Lindesay (1987) compared 94 homosexual men with 100 heterosexual controls. Approximately 14% of the homosexual men were left-handed compared with 9% of the heterosexual men. More interestingly there was a significant trend for the homosexuals, which Annett (1988) has interpreted in terms of a "reduction in right shift". (Marchant-Haycox SE, McManus IC, Wilson GD (1991) Left-handedness, homosexuality, HIV infection and aids. Cortex 27: 49) "Height, weight, fatness, muscularity, linearity, biacromial-bi-iliac ratio, and muscle strength were compared for 44 homosexua and 111 heterosexual men. Homosexuals had less subcutaneous fat and smaller muscle/bone development and were longer in proportion to bulk. Their shoulders were narrower in relation to pelvic width, and their muscle strength was less. Linearity and muscularity were related to childhood build and certain behaviors. Urinary metabolites and blood serum lipids were compared for smaller groups (27-28 homosexuals, 109-111 heterosexuals). The homosexuals had lower creatinine and 17-ketogenic steroid levels, lower androsterone-etiocholanolone ration, and higher 11-keto-etiocholanolone. They also had lower triglycerides, phospholipids, cholesterol, and beta-lopoproteins. It was concluded that the data support the thesis of an unidentified common factor underlying physical/personality charateritics and homosexuality." (Evans, R. (1972) Physical and biochemical characteristics of homosexual men. Journal of Consulting and Clinical Psychology 39: pp. 140) "Stater (1962) found that mothers of homosexual sons were significantly older than a general population sample at the time of the son's birth." (Evans, R. (1972) Physical and biochemical characteristics of homosexual men. Journal of Consulting and Clinical Psychology 39: pp. 142) [higher T] "Androgens are hormones which stimulate development of masculine characteristics and are produced by the testes and also by the adrenal cortex in both sexes. Products of androgen metabolism are 17-ketosteroids and have been widely used as an (admittedly inadequate) index of androgenic horone levels. It can be seen from Table 4 that total 17-ketosteroid excretions were virtually identical for the two groups. Two of the fractions, however, showed a significant difference, and a third approached significance. Of interest also is the androsterone-etiocholanolone ratio, which was lower for the homosexuals and supports similar findings reported by Margolese (1970). No speculations were made as to the importance or role of any of the 17-ketosteroids in homosexuality, but it had been predicted by Massion-Verniory (1957) that one of the 17-ketosteroid fractions would be found to differentiate homosexuals." (Evans, R. (1972) Physical and biochemical characteristics of homosexual men. Journal of Consulting and Clinical Psychology 39: pp. 145) "Several homosexuals have written to us suggesting that there is a high rate of lefthandedness in this population, but no study of this claim has yet been reported. A high rate of nonrighthandedness in this population may seem at first to be difficult to explain in the light of some animal experiments. Ward and Weisz (1980) and Dorner, Gotz, and Docke (1983) have shown that, in rats, stress in midpregnancy causes the male offspring to have permanently low free testosterone levels and homosexual behavior. Dorner has reported low free testosterone in human homosexuals, but no other group has yet confirmed this. His group has also reported a higher rate of stress in pregnancy in mothers of homosexuals than in those of controls (Dorner et al. 1983). Low free testosterone has been found in male temporal lobe epileptics in whom altered sexual behavior, including hyposexuality, is frequently seen. The low testosterone level was independent of drug therapy (Toone et al. 1983). If the situation is the human is similar to that in the rat, then one would arrive at the apparently paradoxical conclusion that a group with low free testosterone levels in adult life should have a high rate of anamalous dominance. The answer is, we believe, given by the experiment of Ward and Weisz (1980) showing that when the pregnant rat is stressed, testosterone first rises to higher than normal levels in male fetuses and then drops to permanently low levels. Infants with Klinefelter syndrome may also have very high testosterone in cord blood, becoming hypogonadal only later on. Handedness would, of course, be determined by the level in fetal life, not by adult levels. Netley and Rovet (1982) have recently reported an elevated rate of lefthandedness in Klinefelter syndrome." (Geschwind & Galaburda 1987: 175, Cerebral Lateralization) "A Kinsey Institute study of gay men in the San Francisco Bay area found that 75 percent had had more than one hundred partners. 25 percent had had more than one thousand." (Ridley 1993: 182, The Red Queen) "Research in Britain, America, and Germany has all confirmed that a prenatal exposure to deficiency of testosterone increases the likelihood of a man becoming homosexual. Men with an extra X chromosome and men exposed in the womb to female hormones are more likely to be gay or effeminate, and effeminate boys do indeed grow up to be gay more often than other boys. Intriquingly, men who were conceived and born in periods of great stress, such as toward the end of World War II, are more often gay than men born at other times. (The stress hormone cortisol is made from the same progenitor as testosterone; perhaps it uses us the raw material, leaving less to be made into testosterone.) The same is true of rats: Homosexual behavior is more common in rats whose mothers were stresses during pregnancy. The things that male brains are usually good at gay brains are often bad at, and vise versa. Gays are also more often left-handed than heterosexuals, which makes a sort of sense because handedness is affected by sex hormones during development, but it is also odd because left-handed people are supposed to be better at spatial tasks than right-handers. This only demonstrates how sketchy our knowledge still is of the relationship between genes, hormones, brains, and skills." (Ridley 1993: 264-5, The Red Queen) "The most compelling of the new evidence for the gay gene is that fraternal twins, carried in the same womb and reared in the same household, have only a one-in-four chance of being gay. Identical twins, on the other hand, with the same nurture and the same nature, have a one-in-two chance of being gay. If one identical twin is gay, the chances that his brother is also gay are 50 percent. There is also good evidence that the gene is inherited from the mother and not from the father. (Ridley 1993: 280, The Red Queen) "But in August 1992, the presigious journal Science published a paper by neurobiologist Simon Levay demonstrating just such a difference. And it's a whopper of an interesting one. It concerns the hypothalamus, a part of the brain central to sexual behavior. The size of one subregion at the front of the hypothalamus, known by the not terribly titillating title of the third interstitial nucleus, differs by sex; males have a larger one than do females. Levay reported that homosexual men have smaller nuclei than do heterosexual men---as small, in fact, as those found in women......his sample was small, and the brain tissue he examined came from AIDS patients..." (Sapolsky 1997: 30, TheTrouble With Testosterone) "Perhaps this explains why studies show that girls brought up without fathers in early childhood experience fewer orgasms when they are married and why inappropriate or inadequate fathering seems to be a major factor in the development of lesbianism." (Badcock, C. (1991) Evolution and Individual Behavior: An Introduction to Human Sociobiology Oxford: Blackwell.pp. 241) "The outcome discussed above would correspond to only one of the possiblities suggested by the findings of Freud. The other is represented by the so-called negative resolution of the Oedipus complex: one in which the boy identifies more with his mother than with his father and which is found to be implicated in many cases of homosexuality in males. Phychoanalytic observations often indicate that a common reason for such an outcome is that the father is absent, inadequate, or for some other reason fails to provide a successful basis for his son's identification with him. Nor are Freudians alone in finding this. A surprisingly large number of studies by mainstream, academic psychologists have come to exactly the same conclusion. A comprehensive summary of the dozens of separate studies in question concludes that the degree of the son's masculinity is frequently found to be related to the father's perceived role within the family, with men who tend to play a passive, feminine role or who are dominated by their wives tending to have less masculine sons. Such studies also show that an inadequate indentification with a strong, masculine father is a prime factor in the development of homosexual, reactive hypermasculinity, and various kinds of psychological and social problems in sons." (Badcock, C. (1991) Evolution and Individual Behavior: An Introduction to Human Sociobiology Oxford: Blackwell.pp. 244) "Cohen and Forget (submitted for publication) compared right-handed men, women, and genetic male transexuals on verbal and nonverbal dichotic tasks to investigate relations between hormone therapy and auditory cerebral specialization of speech and non-speech stimuli in adults. In verbal tasks, the usual REA obtained for all subject groups; in nonverbal tasks, results revealed a left ear advantage in the processing of nonverbal information for men only; women and transsexuals exhibited similar performances in nonverbal tasks. Cautious interpretation of the data is some possible hormonal involvement, in adults, in the modulation of right hemispheric cognitive processing. In light of the inherent difficulties of isolating the early influence of testosterone, the studies that effectively submit a test of the GBG hypothesis are those of Grimshaw, Bryden, and Finegan (1993), and Grimshaw, Niccols, and Finegan (1990) who attempting to determine whether dichotic listening performance and frequency of occurance of left-handedness were correlated with levels of testosterone measured prenatally, during amniocentesis, in populations of children. These two studies do not support GBG's claim that higher levels of testosterone are associated with reduced left hemisphere dominance. If anything, the reverse appeared to be true." (Forget, H. & Cohen, H. (1994) Life after Birth: The Influence of Steroid Hormones on Cerebral Structure and Function is Not Fixed Prenatally. Brain and Cognition 26: 247) "A study of handedness, dyslexia, stuttering and twinning, was included in a study of sexual habits of homosexual men. A questionnaire was mailed to homosexuals, and 394 forms suitable for data analysis were received. The results showed an increased rate of lefthand writing (17.5% compared to 8-8.4%), and a clear left shift. There were increased occurrence of both stuttering (7.1% compared to 1.6%) and reading difficulties (7.9% compared to 1-3%). The incidence of twins was lower than the population (1.3%). The results confirm earlier attempts to show a left shift in homosexuals, and support Geschwind's hypotheses about etiological factors for both lefthandedness and homosexuality. " (Gotestam, K.O., Coates,T.J., Ekstrand, M. (1992) Handedness, dyslexia and twinning inhomosexual men. International Journal Neuroscience 63 (3-4): 179)
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