There is now overwhelming evidence, particularly from the field of neuroscience and neuroendocrinology demonstrating unequivocally the strong biological, inborn basis for sexual orientation. This evidence has been demonstrated behaviourally, through imaging and detailed morphological and cytological investigations both in humans and other animals.
Qcmbr, once again you have demonstrated brilliantly that you are as ignorant as you are bigoted. This is not particularly surprising given that you received your science education from the book of mormon (the fictional testimony of jesus christ) and the latter-day ignoramuses. Next time, do some research before spouting off a load of horseshit about subject matter you neither understand nor are even remotely aware of.
Proc Natl Acad Sci U S A. 2006 May 23;103(21):8269-74. Epub 2006 May 16.
Brain response to putative pheromones in lesbian women.
- Berglund H ,
- Lindstrom P ,
- Savic I .
Department of Medicine, and Stockholm Brain Institute, Karolinska University Hospital, Karolinska Institutet, 171 76 Stockholm, Sweden.
The progesterone derivative 4,16-androstadien-3-one (AND) and the estrogen-like steroid estra-1,3,5(10),16-tetraen-3-ol (EST) are candidate compounds for human pheromones. In previous positron emission tomography studies, we found that smelling AND and EST activated regions primarily incorporating the sexually dimorphic nuclei of the anterior hypothalamus, that this activation was differentiated with respect to sex and compound, and that homosexual men processed AND congruently with heterosexual women rather than heterosexual men. These observations indicate involvement of the anterior hypothalamus in physiological processes related to sexual orientation in humans. We expand the information on this issue in the present study by performing identical positron emission tomography experiments on 12 lesbian women. In contrast to heterosexual women, lesbian women processed AND stimuli by the olfactory networks and not the anterior hypothalamus. Furthermore, when smelling EST, they partly shared activation of the anterior hypothalamus with heterosexual men. These data support our previous results about differentiated processing of pheromone-like stimuli in humans and further strengthen the notion of a coupling between hypothalamic neuronal circuits and sexual preferences.
Proc Natl Acad Sci U S A. 2005 May 17;102(20):7356-61. Epub 2005 May 9.
Brain response to putative pheromones in homosexual men.
- Savic I ,
- Berglund H ,
- Lindstrom P .
Department of Clinical Neuroscience, Karolinska University Hospital, 171 76 Stockholm, Sweden. [email protected]
The testosterone derivative 4,16-androstadien-3-one (AND) and the estrogen-like steroid estra-1,3,5(10),16-tetraen-3-ol (EST) are candidate compounds for human pheromones. AND is detected primarily in male sweat, whereas EST has been found in female urine. In a previous positron emission tomography study, we found that smelling AND and EST activated regions covering sexually dimorphic nuclei of the anterior hypothalamus, and that this activation was differentiated with respect to sex and compound. In the present study, the pattern of activation induced by AND and EST was compared among homosexual men, heterosexual men, and heterosexual women. In contrast to heterosexual men, and in congruence with heterosexual women, homosexual men displayed hypothalamic activation in response to AND. Maximal activation was observed in the medial preoptic area/anterior hypothalamus, which, according to animal studies, is highly involved in sexual behavior. As opposed to putative pheromones, common odors were processed similarly in all three groups of subjects and engaged only the olfactory brain (amygdala, piriform, orbitofrontal, and insular cortex). These findings show that our brain reacts differently to the two putative pheromones compared with common odors, and suggest a link between sexual orientation and hypothalamic neuronal processes.
Proc Natl Acad Sci U S A. 1992 Aug 1;89(15):7199-202.
Sexual orientation and the size of the anterior commissure in the human brain.
Department of Anatomy and Cell Biology, University of California, Los Angeles 90024.
The anterior commissure, a fiber tract that is larger in its midsagittal area in women than in men, was examined in 90 postmortem brains from homosexual men, heterosexual men, and heterosexual women. The midsagittal plane of the anterior commissure in homosexual men was 18% larger than in heterosexual women and 34% larger than in heterosexual men. This anatomical difference, which correlates with gender and sexual orientation, may, in part, underlie differences in cognitive function and cerebral lateralization among homosexual men, heterosexual men, and heterosexual women. Moreover, this finding of a difference in a structure not known to be related to reproductive functions supports the hypothesis that factors operating early in development differentiate sexually dimorphic structures and functions of the brain, including the anterior commissure and sexual orientation, in a global fashion.
1: Arch Sex Behav. 1995 Dec;24(6):585-93. Links
Cerebral laterality in homosexual males: preliminary communication using magnetoencephalography.
- Reite M ,
- Sheeder J ,
- Richardson D ,
- Teale P .
Department of Psychiatry, University of Colorado Health Sciences Center, Denver 80262, USA.
MEG-based auditory M100 source location in the left and right hemispheres of 8 strictly homosexual and 9 strictly heterosexual males were compared to determine if this measure of interhemispheric laterality varies as a function of sexual orientation. MEG fields evoked by auditory tone pips were recorded from left and right hemispheres in response to contralateral ear stimulation. The source of the 100-msec latency component, generated in the superior temporal gyrus, was estimated using a least squares inverse solution algorithm. Auditory sources in heterosexual men were significantly further anterior in the right hemisphere compared to the left hemisphere. Source locations in the homosexual men did not exhibit significant interhemispheric asymmetry, being similarly located in both hemispheres. Findings suggest an anatomic and/or functional difference in the superior temporal gyrus of at least some homosexual men.
Horm Behav. 1995 Mar;29(1):31-41.
A comparison of LH secretion and brain estradiol receptors in heterosexual and homosexual rams and female sheep.
- Perkins A ,
- Fitzgerald JA ,
- Moss GE .
Carroll College, Helena, Montana 59601, USA.
This study examined endocrine components of sexual orientation of male sheep. Sexual orientation of adult rams was identified through standardized sexual performance tests. Four rams that copulated with ewes, four rams that never mounted females and copulated with males, and eight ewes were used in the experiments. Exogenous estradiol benzoate (50 micrograms, i.m.) stimulated (P < .05) a preovulatory-like LH surge 16-22 hr after administration to females. Estradiol did not (P > .05) affect LH release of heterosexual or homosexual rams. Thirty days after the estradiol challenge, sheep were euthanized and areas of the amygdala (AMY), hypothalamus (HYP), anterior pituitary (AP), and preoptic area (POA) of the hypothalamus were collected. Occupied and unoccupied content of estradiol receptors (ER) was determined. The content of ER in the amygdala of both homosexual rams and ewes was similar, but less than (P < .05) the content of ER in heterosexual rams. The ER content measured in other brain regions did not differ by sex or orientation. In summary, results from these data show that the preovulatory LH surge mechanism that is a characteristic of the female does not occur in either homosexual or heterosexual rams. Conversely, the ER content of the AMY of homosexual rams is similar to that of ewes and differs from the heterosexual male. Differences in ER content between heterosexual and homosexual rams imply that the amygdala serves as a link for input from potential mates. These data suggest that the amygdala not only plays a role in sexual behavior but may be involved in sexual orientation of rams.
Curr Biol. 2006 Jan 10;16(1):63-8.
Face perception is modulated by sexual preference.
Institute of Neuroradiology, University of Zurich, Zurich, Switzerland; Institute for Biomedical Engineering, Swiss Federal Institute of Technology, Zurich, Switzerland.
Face perception is mediated by a distributed neural system in the human brain . The response to faces is modulated by cognitive factors such as attention, visual imagery, and emotion ; however, the effects of gender and sexual orientation are currently unknown. We used fMRI to test whether subjects would respond more to their sexually preferred faces and predicted such modulation in the reward circuitry. Forty heterosexual and homosexual men and women viewed photographs of male and female faces and assessed facial attractiveness. Regardless of their gender and sexual orientation, all subjects similarly rated the attractiveness of both male and female faces. Within multiple, bilateral face-selective regions in the visual cortex, limbic system, and prefrontal cortex, similar patterns of activation were found in all subjects in response to both male and female faces. Consistent with our hypothesis, we found a significant interaction between stimulus gender and the sexual preference of the subject in the thalamus and medial orbitofrontal cortex, where heterosexual men and homosexual women responded more to female faces and heterosexual women and homosexual men responded more to male faces. Our findings suggest that sexual preference modulates face-evoked activation in the reward circuitry.
Brain Res. 2004 Oct 22;1024(1-2):251-4.
Differential brain activation in exclusively homosexual and heterosexual men produced by the selective serotonin reuptake inhibitor, fluoxetine.
- Kinnunen LH ,
- Moltz H ,
- Metz J ,
- Cooper M .
Committee on Human Development, University of Chicago, 5848 S. University Avenue, Chicago, IL 60637, USA. [email protected]
A number of studies have shown a relationship between "sexual orientation" and size of various brain nuclei. We hypothesized that neurotransmitter differences might parallel neuroanatomical differences in the hypothalamus. We administered 40 mg of fluoxetine as a challenge to the serotonergic systems of exclusively homosexual and exclusively heterosexual men and measured cerebral metabolic changes with fluorodeoxyglucose positron emission tomography (FDG-PET). The metabolic differences we observed might reflect underlying neurochemical differences between homosexual and heterosexual men.
Science. 1991 Aug 30;253(5023):1034-7.
- Comment in:
- Science. 1991 Nov 1;254(5032):630.
A difference in hypothalamic structure between heterosexual and homosexual men.
Salk Institute for Biological Studies, San Diego, CA 92186.
The anterior hypothalamus of the brain participates in the regulation of male-typical sexual behavior. The volumes of four cell groups in this region [interstitial nuclei of the anterior hypothalamus (INAH) 1, 2, 3, and 4] were measured in postmortem tissue from three subject groups: women, men who were presumed to be heterosexual, and homosexual men. No differences were found between the groups in the volumes of INAH 1, 2, or 4. As has been reported previously, INAH 3 was more than twice as large in the heterosexual men as in the women. It was also, however, more than twice as large in the heterosexual men as in the homosexual men. This finding indicates that INAH is dimorphic with sexual orientation, at least in men, and suggests that sexual orientation has a biological substrate.