Comments on: Multiple factors involved in sexual orientation: New study

By: carole

carole — Thu, 03 Sep 2009 16:34:53 +0000

@Evan,

The amygdala differences are more interesting, but, again, we have to see the study.

Here’s an interesting article–for what it’s worth, once again, activity in the amygdala is the focal point.
http://www.livescience.com/culture/090903-seizure-switch.html

By: RandomEffect

RandomEffect — Thu, 04 Dec 2008 01:17:48 +0000

One thing I’ve thought of that I bet nobody else has mentioned is that part of the chance of your sexual orientation may be what we think of as randomness. Of course nothing is really random if you look at it very closely. I’m talking about the Butterfly Effect. This will probably confuse a lot of people, but bare with me. The Butterfly Effect comes from the idea that if a butterfly flaps its wings it can cause a tornado on the other side of the world. Basically all the matter and energy in the world is physically connected somehow so a physical or chemical reaction that happens anywhere in the world will have some influence on all the other ones that happen in the future. If one was different it might in some cases change the whole outcome, but usually you’d probably have to many be different, maybe even millions for it to affect the outcome.
The human body is basically matter and energy interacting together to somehow produce consciousness and everything that goes with it (desires, feelings, etc.), so there’s no reason why another chemical reaction, especially one that’s in your body wouldn’t have any impact on future ones. What ever chemistry produces attraction towards someone is the outcome of a very long, chemical equation containing all the chemicals that have ever interacted with your brain and all the chemicals that interacted with those chemicals and so on and so forth. So that would mean that had millions of seemingly unrelated factors been different (you ran one day instead of walking/vice versa, you eat a little more/less, how long you slept, what you watched on tv, even just stepping down your foot one inch forward/backward (since every action essentially sends out chemical signals)) your sexual orientation could be different. And it wouldn’t even be consistent like for example if everytime you overslept that increased your chances of being heterosexual. Instead it would be like you oversleep and that changes a variable in the chemical equation and how that affects your sexual orientation would depend on how it interacts with all the other variables so sometimes it could make you more likely to be straight, sometimes gay, and sometimes bi.
Final note, what do you think caused you to like the foods you like or the smells you like? You probably just think you “just do”. Of course something determines that 2, millions of factors including a few ones where the relation can be easily seen and millions and even billions that would seem to have no logical reason to affect the outcome but still do through the Butterfly Effect.

By: Evan

Evan — Fri, 04 Jul 2008 16:30:13 +0000

Drowssap,
Anxious personality is based on stable brain patterns that are probably the result of genetics, hormones and how these two factors conspired to influence someone to have certain behavioural tendencies, like avoiding aggressive games or confrontational situations. Actually a recent study shows that trait is manifested all the time as a form of vigilence even in quiet environments. Being that aggresiveness and competitiveness are male-typical characteristics, these anxious kids probably perceived their same-sex peers in a manner that is typical for the opposite sex (they could have been ‘kitchen boys’ or ‘sissies’). This might explain the same amygdala patterns in male homosexuals and female heterosexuals. They used their brain in the same way in relation to the male sex, but the causes might not necessarily be the same. It could be that some genetic factors predispose some men to greater anxiety which is atypical for their gender. This factor alone cannot cause atypical attractions, but it probably contributes to the final outcome. Still, the amygdala is involved in many cascading effects throughout the entire body. There are unexpected relations between these effects, like:
–greater anxiety which can also increase pain sensation (hyperalgesia),
–greater anxiety can increase physiological arousal,
–greater amygdala activation can cause greater visceral sensitivity along the brain-gut axis – especially in the lower gastrointestinal tract (intestines and anus).
But the amygdala does not play a role in these reactions by itself, it’s integrated in a number of specialised networks. For instance, a probable network for sexual behaviours includes the amygdala that makes the emotional assessment of stimuli, the ventromedial nucleus of the hypothalamus (which triggers lordosis in the females and mounting in the males) and the periaqueductal gray (involved modulation of pain, defensive behaviour, lordosis). If these areas are somehow less masculinised or too effeminised they might trigger body reactions that are atypical for an individual’s sex status.
That can happen in many ways. A combination of genetically caused androgen receptors problems and how they interact with a certain level of hormonal exposure. Or it could only make a difference in a few specialised areas, regardless of the overal level of hormonal exposure.
But as I said there must be another brain area that manages aggressiveness and allows a greater degree of stimuli input in the stress system, which overwhelms it. This is known as a sensory gating problem and has caused many disorders, which might also account for straight women’s and gay men’s greater vulnerability to stress and mood problems.
So, differences in aggressiveness and sensitivity are probably correlated with gender feelings. But there are too many black boxes in the human system to be able to tell, like scientists who work on animal models, that there could be a switch, upstream the brain circuitry that governs gender-typical dimensions, that can awake different gender potentialities in the same brain. That might be a whole different issue than what scienstists in the field of sexual orientation study right now. Aggressiveness could be a by-product of a region that switches more or less the gender status of an organism. But then, again, why are there no same-sex oriented mice in the wild but there are same-sex oriented monkeys? Maybe humans and higher primates have lost that switch (the vomeronasal organ) and they only rely on the former by-products of gender-typical hormonisation and genetic sex status.

By: Drowssap

Drowssap — Tue, 01 Jul 2008 15:38:49 +0000

Evan

Well, greater anxiety or vigilance might have come handy in dangerous environments, it might be that sensitive men might have had to compensate their lower aggressiveness by greater inventivity.

I think that’s the big question. Do traits like greater sensitivity lead to homosexuality or are these traits biproducts of whatever triggers homosexuality?
My personal guess is that these traits are biproducts of the SSA trigger. The recent Swedish study that found greater amounts of “feminine” wiring in gay men concluded that this wasn’t the result of natural genetics. Something out of the ordinary was responsible. It could have been hormones but even in this case why would the hormones have spiked or washed out or whatever during development?

By: Evan

Evan — Tue, 01 Jul 2008 06:42:25 +0000

Drowssap,
Humans have some peculiarities compared to other species. A teenage phase is one very important for brain development. There is no need to have a perfect bell curve of sexual orientation. The actual bell curve would be that of hormonal factors, like aggresiveness. Throw in some genetic factors for amygdala patterns that predispose some males to anxiety (there is a whole spectrum) and you’ve got a composite bell curve of predispositions slightly amplified in sensitive men (anxiety, vigilance, avoidance). That is why there was a need for culturally enforced gender segregation: to fill the void of a gender switch advantage that was lost. So the bell curve of predispositions had to be adjusted by cultural nudging. You won’t see that in mice, because there is no same-sex oriented mouse in the wild. If they had no gender switch, they would have gone extinct.
What evolutionary advantage gender variance may have had for humans? Well, greater anxiety or vigilance might have come handy in dangerous environments, it might be that sensitive men might have had to compensate their lower aggressiveness by greater inventivity. They could have become healers, shamans or very knowledgeable tribe members that did not need to reproduce as much as the other men. The only chance for a ‘gay’ set of genes to survive would be to have a normal distribution in the population, that maintained a marginal strong effect and a greater weak effect in the rest of the population. So each generation would have a statistical “tail”, but the greater populational effect would be preserved by differing mating strategies: masculine men would pick the best females and less masculine men would settle for females who have a harder time finding mates among the more aggressive males (because of being deterred by their aggressiveness).
Another possibility is that the genetic effects would be the only ones that have been actually passed on, while the hormonal effects might be due to many environmental factors that could be variable at different points in time. Compound factors might be variable across evolutionary ages. I dunno, just a possibility. 🙂

By: Drowssap

Drowssap — Tue, 01 Jul 2008 05:42:50 +0000

Evan

Humans might have left behind that dichotomising mechanism or might have resorted to a mechanism that created more diversity than in other species, actually a curve bell distribution. No ON/OFF positions for gender switching.

Why would we expect to find a naturally occuring bell curve for male, sexual orientation? Hunter gatherer societies accounted for about 250,000 years of human evolution. Roughly 20% of the men had offspring vs. 80% of the females. The competition for women was intense for thousands and thousands of years. Shouldn’t we expect the genes and biological systems that create Kinsey 0 personalities to become fixed among males? That doesn’t mean homosexuality wouldn’t exist. But preferential, life-long homosexuality probably shouldn’t. In what primitive environment would SSA give a man an advantage when competing for women? Having sex with men never comes in handy for spreading DNA. Since women were largely responsible for childrearing we didn’t depend on secondary, male-male relationships to create a backup family structure for children.
By Comparison:
Why would we expect a bell curve in bird migrations? Some fly north, others east and west and some fly south. In reality pretty much all birds fly south for the winter because that system ensures success.

By: Evan

Evan — Tue, 01 Jul 2008 05:01:31 +0000

Drowssap,

I think this is how SSA will be figured out. A research team that doesn’t care one way or the other about Homosexuality is going to find the switch for mate selection in mice or flies or some other animal.

Well, we can’t blame scientists who study human sexual orientation for the poor results in the field. They don’t have the technology to see what’s going on in the womb and neither can they crack people’s skulls open and plug electrodes to see which circuits fire where and find some switches. Or worse, genetically engineer humans, wait until they grow up and see the results. Or the nightmare case scenario, surgically remove sexually dimorphic brain nuclei and watch people acting like opposite-sex sexual zombies. That’s like Dawn of the Dead!
Now back to reality. 🙂
Someone who does comparative evolutionary biology must have some knowledge on how these particular systems in the mammalian brain have been passed on from one species to another. They also have homology maps where they can see the correspondent genes across species. Large chunks of the mammalian species genomes have been preserved. Geneticists call them evolutionarily conserved regions (ECRs). There are almost 5000 ECRs conserved between humans’ X chromosome and that of species like mice and rats. Nature didn’t waste genetic material to create a new way to build a mammalian brain; it only refined the advanced species for some tasks, like visual recognition in primates and, later, language in humans. So the principle of “one brain, two-gender circuits flipped by a sexually dimorphic switch according to the physical gender” should apply to humans at least in one respect: the presence of both-gender circuits in the basic foetal template (the female one). Whether there really is a similar switch in humans or it’s related to vision, or has any comparable effects on sexual attractions, that is a matter of great debate. Humans might have left behind that dichotomising mechanism or might have resorted to a mechanism that created more diversity than in other species, actually a curve bell distribution. No ON/OFF positions for gender switching. After all, we are the only species on earth that has a teenage stage. That must have something to say about human sexuality too. Culture and environment must play a big role, especially if the gender switch mechanism has been left behind (:!: Daryl Bem’s idea: the effect of gender segregation on the development of reproductive sexuality). Or, to quote Breedlove again:

“There’s plenty of room in society to influence sex differences,” “Yes, we’re born with predispositions, but it’s society that amplifies them, exagerates them. I believe that–except for the sex differences in aggression. Those differences are too massive to be explained simply by society.”

So it could be as simple as variations in hormonal fixation of aggressiveness + predisposition to anxiety in males and only aggression variation in females. In this case, gender variance in humans might be exactly the effect of a gender switch gone extinct.

By: Drowssap

Drowssap — Tue, 01 Jul 2008 01:13:04 +0000

jayhuck
You are definitely correct, SSA has a measurable genetic component. How it works is the question.
Scenario A)
A gene creates the potential for SSA. Men with this gene, when exposed to the right set of early life, social circumstances become gay. Because our brains have a critical imprint period this fixes more or less for life.
Scenario B)
A gene, when combined with something natural like the right level of maternal hormones triggers SSA.
Scenario C)
A gene creates susceptability to something like a common, cold virus. If men with this gene are exposed to this virus before birth or early in life they become gay.
It’s going to be a version of one of those scenarios. Actually it is probably all of those scenarios. We just don’t know which scenario is the most common. Realistically speaking there could be people who are gay EXCLUSIVELY due to a gene they carry. But everything points towards this group being very small.

By: Drowssap

Drowssap — Tue, 01 Jul 2008 01:02:00 +0000

But, in the last analysis, the effects on the brains of people of the same orientation and gender must be similar, because we have the same biological organ producing the same effect: same-sex attractions.

Yup, no matter how you slice it, something is creating a predictable and reliable set of attractions, in this case SSA. Gay men share something in common, just like straight men must.
2+2=4 and 1+3=4 but the final answer is always 4.

By: Drowssap

Drowssap — Tue, 01 Jul 2008 00:55:11 +0000

Evan

Marc Breedlove, who’s been studying brain hormonisation effects on both mice and humans said:

RIGHT ON!!!! Great find on the Breedlove quote. That makes me feel so good that scientists take this seriously. I knew when you posted that first “When Minnie Turns Mickey” link that this was a huge breakthrough.

In other words, scientists in the field of human sexual orientation still study the haystack or a few side straws, while researchers studying mice have found a needle.

Brilliant point and I think this is how SSA will be figured out. A research team that doesn’t care one way or the other about Homosexuality is going to find the switch for mate selection in mice or flies or some other animal. Once we understand mice, humans probably aren’t 180 degrees different. Obviously we won’t work the exact same way as mice but we aren’t from Mars either. 😎