Darwinists: How Did Homosexuality Evolve?

Gross anatomy of the brain doesn't change but neural pathways, functions, and structure are changing during neuroplasticity and during the life time. It is not gross changes to overall brain anatomy but they are significant.

The leaders of the field write good grants and get more money. Doesn't mean other people "not mentioned on wikipedia" aren't looking at it too.

Here are some peer reviewed articles and studies on amygdala neuroplasticity. It changes according to stressers much like the rest of brain. Reacting and changing to external, intracellular, and extracellular factors.

Adamec, R., and B. 2000. Young. Corticotropin releasing factor and neuroplasticity in coc aine addiction. Neurosci Biobehav Rev. 24:705-23.

Bergstrom, H.C. 2010. Chronic nicotine exposure produces lateralized, age-dependent dendritic remodeling in the rodent basolateral amygdala. Synapse.

Drevets, W.C. 2004. Neuroplasticity in mood disorder. Dialogues in Clinical Neuroscience 6: 209.

Holder, M.K., and J.A. Mong. 2010. Methamphetamine enhances paced mating behaviors and neuroplasticity in the medial amygdala of female rats. Horm Behav.

Li, He, et al. 2005. Neuroplasticity and Calcium Signaling in Stressed Rat Amygdala. US Gov. Report.

McEwen, B.S., and S. Chattarji. 2004. Molecular mechanisms of neuroplasticity and pharmacological implications: the example of tianeptine. Eur Neuropsychopharmacol. 5:497-502.

Pereno, G.L., and C.A. Beltramino. 2010. Timed changes of synaptic zinc, synaptophysin and MAP2 in medial extended amygdala of epileptic animals are suggestive of reactive neuroplasticity. Brain Res 1328:130-8.

Rademacher, D.J., et al. 2010. Amphetamine-associated contextual learning is accompanied by structural and functional plasticity in the basolateral amygdala. J Neurosci. 30: 4676-86.

Tye, K.M. 2010 Methylphenidate facilitates learning-induced amygdala plasticity. Nat Neurosci 13:475-81.

I liked the last one. Learning induced amygdala plasticity. The brain is very plastic although on a macro scale the changes are minute and do not overall change the areas of the brain drastically.



To arbiture:

I never said genetics had anything to do with homosexuality or the cause. I was actually saying that brain characteristics of homosexuals do not represent a genetic relationship. I said homosexuality could be passed down genetically and still survive even though two males or two females could not produce offspring.

I imagine that there are genotypes that increase the chances of homosexuality. Also there are certain social and developmental factors involved.

The ah-ha moment theory would be cool to look into. So far I know that the neuroplasticity is often associated with different neurotransmitters and chemicals. The production of these chemicals from certain activities or emotion (stress, learning, happiness) ultimately affect neural wiring and pathways (neuroplasticity). however I haven't found if any of "ah-ha" moments are the direct product of changes in neural pathways. It would be cool but tough to do.

Who did I call a heratic?

About the politically correct thing. Homosexuality is a touchy subject. I don't care what people do with their lives as long as it doesn't negatively affect me. People get offended easily and I am just trying to explain the facts and research i scientific terms. Where were you going with this besides explaining political correctness?


To Mumbotron:

Yeah skin pigmentation you are quite wrong. Black skin is the ancestral trait. We evolved out of africa leaving the areas where dark skin pigmentation is necessary to protect against UV. Lighter skin pigmentation evolved in milder climates and lower altitudes to allow enough vitamin d production.

Harding, Rosalind M., et al. 2000. Evidence for variable selective pressures at MC1R. American Journal of Human Genetics 66: 1351–1361.

Jablonski, N.G., and G. Chaplin. 2000. The evolution of human skin coloration. Journal of Human Evolution 39: 5

[edit on 26-4-2010 by Grant123]

reply to post by Grant123


While I was wrong that neuroplasticity does not occur in the amygdala, it is still in the same way as the rest of the brain. It is simply making new connections between neurons. If I remember the original article it was claiming that the gross anatomy of the amygdala was different. Since this is something that is static, the change cannot be caused by the postnatal environment.

By the way, I just want to say that its great to see someone else who is studying in this area.

Do you think left-handedness (which is an abnormality in terran human adults exhibited in both male and females) is genetic?

Or is left-handedness 'a choice'? If so, who in their right mind would want to CHOOSE to be odd and stared at all the time?

Considering that 9% of the adult terran human population 'considers themselves to be primarily' left handed and 9% of the adult terran human population considers themselves to be 'primarily homosexual', I mean.

Since left handedness is clearly an abnormal / weaker (less competitive) condition for adult modern terran humans to be in, why has not evolution weeded these abnormal persons out of the gene pool by now?

Homosexuality has been around since man has been around

It has not evolved, only been categorized and judged

If you look back to the Greeks they like walked with men and didn't even acknowledge women as their equals

Today, you see these countries where the women have to be all covered and can't socialize.

It is said in the bible about Man being created, then Wo-man was created from him...

This means that Man would have the genetics to have the feelings of the woman. The original purpose was to divide these two states of being.

Man and Woman empower eachother and become greater as one, when essentially they were always one...

Anyways, chemicals ranging from caffeine to anything really has a massive influence on the human body

The body does not comprehend chemicals that are foreign to it, for most chemicals the body treats it as estrogen

The more the baby is presented with estrogen the less it will be able to forimidably wire itself as a A-testosterone, B-Estrogen mindset

When your boy baby is wired up BA then cultural and social stigmas as well as MMS will already show your child that it is gay.

But the world is starting to understand it is not a choice to be gay but a choice to participate in homosexual activity...

It is not about "not being able to express your true desires" but understanding that you have been born with a handicap and must live with it as a downsyndrome child or any other life long dibilitating disease

Homosexual behavior is viewed in thousands of species. So you only have 2 choices....

(a) For the Evolutionists..... It is a type of hormonal mutation/variation that serves no real point in any species, which is why it is not passed on genetically. So chalk it up the same as any other random mutation.

(b) For the Creationists...... God created the potential for homosexual behavior in all species for some divine reason we are incapable of understanding. It could not possibly be the Devils work, as animals have no souls to corrupt according to Christianity, correct ?

reply to post by Titen-Sxull


" lacking knowledge about something is no excuse to slap a "God did it" label on. "

Isn't that the origins of most religions

reply to post by prochronism


A 1979 study by the University of Minnesota; Sources of human psycological differences; "The Minnesota study of twins reared apart". T.J. Bouchard et al. attempted to quantify what personality and as a result behavioural traits were determined by genetics, and which on environment. The protocol involved identical twins seperated shortly after birth, and adopted by unreleated parent's. Each twin was raised in a different home, and were unaware they were adopted, or had a twin.

The results were quite amazing. The personality, expressed by their behaviour was much more likely to be nearly identical then the population at large. When we recognize some one's personality, at that point one could say there is enough detail to recognize their personality "fingerprint". The sudy found if one twin was a fireman, the other was a fireman, a teacher, business man etc. Also, things we consider one's personal taste, such as the kind of music prefered, a favorite color, intrest in hobbies, political views, etc. Other behavioural charecteristics such as being a thrill seeker, applied as well.

It seems genetic's determines our personality, and how we express it with in if a given environment. The fact we have so varied behaviour in people, seem's to be because as a species can adapt to different circumstances, what ever the core personality.

reply to post by arbiture


I believe the heritability of personality is currently estimated to be between 30-50%. So like many things that are influenced by genetics only about half the variability can be explained by genes. In the end most things are an equal combination of genes and environment.

reply to post by Grant123


I did not call you a herritic. I use that term to define how someone is viewd by others when they don't appear to share the view of any group goverened by politically correct "bylaws". One can be labeled PIC not based on what is, but what others think it is. I also try to explain things in scientific terms. Prejudice, the value we asign to things, and whim, in time die. A perspective based on more solid ground is more usefull.

reply to post by Sigismundus


The Left hand thing...yea that's a social thing. You can change which hand is dominant and your brain will change in accordance. It just takes some practice and time to develop t Again start at wikipedia.

Being left handed is in no way abnormal or weaker in an evolutionary standpoint (send some proof if you got some). Just our society has higher concentrations of righties. (And read my previous post for why a trait is hard to weed out).

reply to post by AaronTheSpeaker


"The body does not comprehend chemicals that are foreign to it, for most chemicals the body treats it as estrogen"
-Umm definately completely false. Show some evidence. phthalates have similar response as estrogens.

Don't quote the bible for scientific logic that will get you nowhere.

Estrogen does tend to be found unnaturally in males due to high pollution and cities unable to afford charcoal water filters. That does tend to mess with our neurobiology. Thats no good. It messes with hormonal processes and development of neural pathways.

I wouldn't say homosexuality is a handi-cap.

reply to post by thedeadtruth


I would imagine that right now the scientific consensus is that there are genotypes that increase the chances of homosexuality (genetic predispositions). However development and social setting do have a large effect.

reply to post by Xcalibur254


The article states

"In heterosexual men and gay women, there were more nerve "connections" in the right side of the amygdala, compared with the left.

The reverse, with more neural connections in the left amygdala, was the case in homosexual men and heterosexual women. "

Which is exactly what was occurring in the studies I previously posted. No drastic changes in the amygdala just changes in the wiring. Some studies documented differing connections from the amygdala to the hippocampus. The hemisphere sizes i'd imagine could change more drastically given that more neuroplasticity has been documented in the lobes.

But the original poster did quote a blog by a guy very closely associated with the southern church. I can't find much info on the guy.


[edit on 26-4-2010 by Grant123]

reply to post by Grant123


Concerning being left handed, yes you can learn to express motor skills in a different way. People who loose limbs do it all the time. That retraining can be based on practicle considerations, or social. In the 1930's my Mom whos left handed could use only her right in school. Thats because then the Catholic church believed the left hand was associated with evil.

But it doesn't change were all born favoring one hand, the other, or both. It's dealing with something were born with, being a certain way, every one can identify with.

reply to post by Grant123


I stand corrected. For some reason I remember the article stating that in one sex the amygdala was larger in one hemisphere, while in the other sex it was equal sizes in both hemispheres.

Published paper which attempts to reconcile the development of the "homosexual" gene when it seems to exist in opposition of Darwinian evolution. The subject: since male homosexuals don't mate with the opposite sex, shouldn't any ‘genes promoting homosexuality’ have died out of the population by now?

The foundation of this paper is:
Abstract
Several lines of evidence indicate the existence of genetic factors influencing male homosexuality and bisexuality. In spite of its relatively low frequency, the stable permanence in all human populations of this apparently detrimental trait constitutes a puzzling ‘Darwinian paradox’. Furthermore, several studies have pointed out relevant asymmetries in the distribution of both male homosexuality and of female fecundity in the parental lines of homosexual vs. heterosexual males. A number of hypotheses have attempted to give an evolutionary explanation for the long-standing persistence of this trait, and for its asymmetric distribution in family lines; however a satisfactory understanding of the population genetics of male homosexuality is lacking at present. We perform a systematic mathematical analysis of the propagation and equilibrium of the putative genetic factors for male homosexuality in the population, based on the selection equation for one or two diallelic loci and Bayesian statistics for pedigree investigation. We show that only the two-locus genetic model with at least one locus on the X chromosome, and in which gene expression is sexually antagonistic (increasing female fitness but decreasing male fitness), accounts for all known empirical data. Our results help clarify the basic evolutionary dynamics of male homosexuality, establishing this as a clearly ascertained sexually antagonistic human trait.

The full version of the paper:

Sexually Antagonistic Selection in Human Male Homosexuality

A synopsis of the findings of this study can be found at Physorg.

Study shows male homosexuality can be explained through a specific model of Darwinian evolution

Edit to correct links and fix stupid syntax.

[edit on 26 Apr 2010 by schrodingers dog]

Originally posted by wrathchildI think we have evolved to out-smart evolution.

Yup. Here's a link to something I was reading about awhile ago.

www.whas11.com...

I think the idea is that smarter people behave in ways that are contrary to evolution, and this is very unique to humans. Of course, I don't think this relates to gays at all. I'm pretty sure that there are evolutionary benefits to homosexuality, whereas there are no evolutionary benefits for someone choosing to be a flaming liberal if they're making a ton of money, and most of the warcry yelling libs that I know are very intelligent, wealthy people.

How is it not a handi cap? You an animal...you are supposed to be attracted to females bilogically, in order to reproduce....somewhere along the lines that got screwed up....

No one is saying it is wrong to be gay, but i will not agree it is not a malfunction, and therefore a handicap

As for estrogen, BPA the chemical in all plastics, including the sealent in all your tin food. There is tons of estrogen being pumped into the system, milk contains so much estrogen and the hormones being used on the cows is increasing that as well.

There was a study done that women had high estrogen rates during pregnancy; The boys from these high estrogen women were more likely to want to play with dolls and wear girls clothing as children

Originally posted by AaronTheSpeaker


It is not about "not being able to express your true desires" but understanding that you have been born with a handicap and must live with it as a downsyndrome child or any other life long dibilitating disease

Ouch!
May I quote you when I mince into the Social Security office to sign up for disability benefits?

Pardon the levity, but that statement gets a laugh, serious discussion or no.

I guess it is how you take the context of handi cap

Do people hate on the Autistic person who can solve insane arythmetic but can't tie his shoes?

Just because your disability has not messed with your interacting and intelligence skills does not mean deep down you arent wired wrong from the get go

I am not trying to be rude when I say that either, it is ok to be gay, I am just saying there is no way it can be construed to say it is more normal than the biological norm

reply to post by 23refugee


I see you're not trying to be rude, but "a downsyndrome child or any other life long dibilitating disease" is easily construed as such.
I'm not easily offended when the causes of homosexuality and its effects on the species are discussed.
I'm sure, by the same token, that you wouldn't be offended by a frank discussion on the possible detriments your reproduction might have on the species.
Not that easy when it hits close to home.

Actually, I believe in systematic depopulation

As well, you must need a certain amount of assets to have a child

A child costs more than a new car and about as much as a nice house...

You must be approved for those, why not a child?

reply to post by AaronTheSpeaker


BPA is a xenoestrogen. But non-estrogenic chemicals are not treated like estrogens in the body that's just silly.

Of course there is a lot of estrogen pollution. I previously stated this. High estrogen rates in males during development alter sexuality and gender. I previously stated this.

It could be ecologically and socially beneficial for a population to have homosexuals as previously stated. So it isn't necessarily a social handi-cap. They can also reproduce with the opposite sex but are just sexually attracted to the same sex. They are fully functioning humans.

Left handedness is different than sexuality. It has been shown that lefties are at advantage in fighting which may be why it has survived. Again look at my previous post on recessive traits. Left handedness genes are shown in some studies to be associated to detrimental health conditions.



[edit on 26-4-2010 by Grant123]