--- The Fool <[EMAIL PROTECTED]> wrote: > http://www.arktimes.com/reporter/030321reportera.html
I think this has been mentioned before, but there is some evidence for biological differences between hetero- and homosexual persons. Here is a theory why homosexuality is not incompatible with biological success (i.e. possible advantage of such genes): http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10763427&dopt=Abstract "The survival of a human predisposition for homosexuality can be explained by sexual orientation being a polygenetic trait that is influenced by a number of genes. During development these shift male brain development in the female direction. Inheritance of several such alleles produces homosexuality. Single alleles make for greater sensitivity, empathy, tendermindedness, and kindness. These traits make heterosexual carriers of the genes better fathers and more attractive mates. There is a balanced polymorphism in which the feminizing effect of these alleles in heterosexuals offsets the adverse effects (on reproductive success) of these alleles' contribution to homosexuality. A similar effect probably occurs for genes that can produce lesbianism in females. The whole system survives because it serves to provide a high degree of variability among the personalities of offspring, providing the genotype with diversification and reducing competition among offspring for the same niches. An allele with a large effect can survive in these circumstances in males, but it is less likely to survive in females. The birth order effect on homosexuality is probably a by-product of a biological mechanism that shifts personalities more in the feminine direction in the later born sons, reducing the probability of these sons engaging in unproductive competition with each other." http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11910786&dopt=Abstract "Moderate support was obtained in a sample of 101 gay, bisexual, and heterosexual males for the perinatal hormone theory, which hypothesizes that attenuated levels of androgens during critical periods of male fetal development fail to masculinize and defeminize the brain. Affected individuals develop female-typical sexual orientation and cerebral organization, reflected in visual-spatial abilities and gender nonconformity..." http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11910794&dopt=Abstract "...These results confirm findings from prior research examining age of puberty using nonrepresentative samples and add to a body of literature suggesting that gay/bisexual men may score, on average, in the female-typical direction on certain sex-dimorphic physical and developmental characteristics." http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11910785&dopt=Abstract "There is indirect evidence that heightened exposure to early androgen may increase the probability that a girl will develop a homosexual orientation in adulthood. One such putative marker of early androgen exposure is the ratio of the length of the index finger (2D) to the ring finger (4D), which is smaller in male humans than in females, and is smaller in lesbians than in heterosexual women...We conclude that increased early androgen exposure plays a role in only some cases of female homosexuality, and that the sexual orientation of "femme" lesbians is unlikely to have been influenced by early androgens." http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11564471&dopt=Abstract "...The present study is consistent with animal models suggesting that prenatal stress disrupts the typical sex hormonal milieu within which male fetal brains are sexed, thereby feminizing/demasculinizing the male's sexual orientation. However, little support was found for similar effects of prenatal alcohol exposure. In the case of prenatal nicotine, this study is the first to suggest that this drug has masculinizing/defeminizing effects on the sexual orientation of female offspring." [Prenatal exposure to alcohol of course has undisputed ill effects on the child's intellect, learning ability and impulse control, among others, depending on the amount and timing of exposure.] This large study with twins finds a heritable rather than congenital relation for lesbians: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11206089&dopt=Abstract "...Estimates of the heritability of homosexuality in this sample ranged between 50 and 60% in females but were significantly lower (heritability of approximately 30%) in males." This twin study didn't find a big difference between male-female WRT heritability: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11058483&dopt=Abstract "...Familial factors, which are at least partly genetic, influence sexual orientation. The results of these analyses should be interpreted in the context of low statistical power and the use of a single item to assess the complex phenotype of sexual orientation." http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12230822&dopt=Abstract "...In homosexuals, promiscuous heterosexuals, and bisexuals there was increased digoxin synthesis, reduced membrane Na(+)-K(+) ATPase activity, increased nitric oxide levels, increased tryptophan catabolites, and reduced tyrosine catabolites. This pattern correlated with that obtained in right hemispheric chemical dominance. In nonpromiscuous heterosexuals and left hemispheric chemical dominance there was hypodigoxinemia and the reverse biochemical patterns..." Naturally, at this stage of research, data conflicts frequently: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11988236&dopt=Abstract "Four studies have examined the cross-sectional area of the anterior commissure (AC) for variation with sex, with conflicting results. One also reported the AC to be larger in homosexual as opposed to heterosexual men. We examined the cross-sectional area of the AC in postmortem material from 120 individuals, and found no variation in the size of the AC with age, HIV status, sex, or sexual orientation." http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11116893&dopt=Abstract "...Studies of relationships between genetics on the one hand and sexual orientation and behavior on the other are theoretically obscure and have thus far failed to prove a trustworthy connection. While there is indeed a difference in total brain size--men's brains are heavier than women's--it is not known whether this difference has any import beyond the fact that men have larger bodies. The existence of differences in brain lateralization and the size of the corpus callosum have been powerfully dismissed in several recent reviews..." My personal take: sexual orientation is generally not a choice, but fixed by time of birth. There are of course individuals who experiment out of curiosity, and no doubt some change orientation because of childhood experiences. Change in behavior as an adult is also possible, but this isn't "proof" that *orientation* is altered (IOW, I could, by a great act of will, refuse to ever consume chocolate again -- but that wouldn't change my desire for it! :} ). Debbi __________________________________________________ Do you Yahoo!? Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop! http://platinum.yahoo.com _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
