Is homosexuality genetic? [Archive]

BillHoyt

27th March 2003, 06:43 AM

Originally posted by Biker Babe
No it isn't how could it be, unless you prescribing to the thought the homosexual gene is carried and passed on like any other genetic marker ot trait?
How would that then go to explain a family history of continous 'hetrosexual 'people and then one day up pops a non hetrosexual person into the mix?

A recessive allele could do exactly that: "hide" for generations.

As for the "wouldn't evolution preclude this" argument, the short answer is no. The longer answer is that many unfit (in the evolutionary selection sense) alleles are maintained simply by a combination of mutation rates and genetic drift. The even longer answer is that you have to factor in human social factors which, for millenia, forced homosexuals into the closet. Many married and had children. Many continue to marry and have children before they finally discover their homosexuality and give up the heterosexual ruse.

To the direct question of what might genetically dictate this, I'd point your attention to the fruit fly mutation found in 1963. The mutant males attempted to mate with other males, and ignored females. The mutation was originally named fruity, but has since been renamed fruitless.American Scientist (http://www.americanscientist.org/Issues/Sciobs01/sciobs0111gene.html)

Cheers,

UnrepentantSinner

27th March 2003, 07:45 AM

In mammals sometimes genes develop that are social and don't necessarily effect direct procreative efforts. Compassion for the sick, dying and retarded have no evolutionary value for direct procreative efforts, but we have them anyway.

It's all a product of being a social being.

Besides {political incorrectness} where would we get our choreographers and interior decorators from? {/political incorrectness}

arcticpenguin

27th March 2003, 08:16 AM

Here's the best evidence yet for a genetic basis of homosexuality: http://news.bbc.co.uk/1/hi/sci/tech/2266135.stm

Someone engineered a gene such that homosexual behaviour could be triggered by temperature. It's clear and reproducible. Oh, and it's in Drosophila fruit flies. Good luck extrapolating to human bahaviour.

Dymanic

27th March 2003, 08:36 AM

I wonder if anyone's ever done a study on whether homosexuality in humans is more prevalent in warmer climates?

Frenchy

27th March 2003, 08:52 AM

Denise

27th March 2003, 09:02 AM

I've read that the denser the population, the higher percentage of homosexuality. I haven't studied it, or seen any studies, but I have read about it. Have there been studies of percentage of homosexual behavior in animal colonies with high density vs low density?

If it is, in fact, there is a higher number of homosexual animals in denser populations then I think it would have an evolutionary advantage. That is, of course, if the animals do not reproduce. It allows for less offspring for competition on scarce resources.

Of course, the question would still remain if homosexuality is genetic or not. Maybe it's not tied to the genes but hormones that are bathing the fetus in the womb depending on the situation of the population.

BillHoyt

27th March 2003, 09:18 AM

If this so called homosexual gene pops up in a heterosexual 9th generation , are you claiming that they have been carrying it recessively, how is that possible?

I would be more inclined to go with a view that it is a hormonal and brain chemical change that cause this. It is not sex but a gender cause.

Frenchy,

Let's take this away from homosexuality for a moment, and look strictly at recessive/dominant alleles. How can a recessive gene suddenly "pop up" after several generations? The simple answer is: it doesn't. The recessive allele was always there, not showing itself because it never had the chance. To express itself, a single individual would need to have two of the recessive alleles. All other individuals express the dominant allele.

Okay so far, so why does the recessive "hide"? Let's say that only 10% of the alleles in a population are this recessive one. To show the effects of the allele, an individual needs to have two such alleles. The probability of that happening is .1 x .1 = .01. That is, 10% of the alleles in the population can be this recessive, yet only 1% of the individuals will express the recessive trait.

Cheers,

Titananarchy

27th March 2003, 12:30 PM

A: No there is no homosexual gene in mammals. If there was, then quite rightly, as someone has already pointed out, no way for that homosexual gene to be passed on to the next generation. The key to understanding passing on genetic traits is through the pathway of natural selection.

The cause of homosexuality is not genetic, but it is biological in origin, and it is not a choice, any more than heterosexuality is a choice. It is also not related to environmental conditions, culture, race, creed or any other societal pressure.

garys_2k

27th March 2003, 12:38 PM

BillHoyt

27th March 2003, 12:46 PM

Originally posted by Titananarchy
A: No there is no homosexual gene in mammals. If there was, then quite rightly, as someone has already pointed out, no way for that homosexual gene to be passed on to the next generation. The key to understanding passing on genetic traits is through the pathway of natural selection.

The cause of homosexuality is not genetic, but it is biological in origin, and it is not a choice, any more than heterosexuality is a choice. It is also not related to environmental conditions, culture, race, creed or any other societal pressure.

Titanarchy,

Your first claim here is tantamount to claiming that no early-onset lethal genetic disease exists. This is patently untrue. Your second claim is that something can be biologic yet not genetic. This is also patently absurd. The basic flow of biological information is DNA->RNA->protein. For something to be biologically (rather than culturally) defined, it must perforce have its origins in the genes.

Cheers,

Titananarchy

27th March 2003, 01:47 PM

Originally posted by BillHoyt
[B]

Titanarchy,

Your first claim here is tantamount to claiming that no early-onset lethal genetic disease exists. This is patently untrue.

If the early-onset genetic mutation regularly kills the host before he/she/it is able to reproduce, then yes. There are genetic mutations such as cystic fibrosis, where people with only one half of the information are perfectly fine, but when combined from both parents will produce an early-onset genetic disease. That is different.

Your second claim is that something can be biologic yet not genetic. This is also patently absurd.

Wrong! Terribly sorry Bill, but there's a gap in your knowledge of mammalian reproduction, and in it is the answer to how homosexuality arises and why it is not related (directly) to genetics.

The basic flow of biological information is DNA->RNA->protein. For something to be biologically (rather than culturally) defined, it must perforce have its origins in the genes.

Cheers,

No Bill, it doesn't. There are other mechanisms which come into play with regard to brain structure and function whose origin is not directly the result of genetic mutation.

There is no gay gene. There is however, a biological reason why homosexuality appears in mammals (in general) and humans (in particular)

Sorry garys_2k for sounding too precise about it. Perhaps you unused to definite answers when social scientists and others positively embrace ambiguity and, dare I say it, ignorance. The question of the origin of homosexuality has been polarised between genetics and environmental causes. However mammalian reproduction introduces a third reason which is biological in origin but which does not require a genetic precursor to happen.

boooeee

27th March 2003, 02:58 PM

Wrong! Terribly sorry Bill, but there's a gap in your knowledge of mammalian reproduction, and in it is the answer to how homosexuality arises and why it is not related (directly) to genetics.

What specifically about mammalian reproduction leads to homosexuality? Just curious.

BillHoyt

27th March 2003, 06:13 PM

Originally posted by Titananarchy
If the early-onset genetic mutation regularly kills the host before he/she/it is able to reproduce, then yes. There are genetic mutations such as cystic fibrosis, where people with only one half of the information are perfectly fine, but when combined from both parents will produce an early-onset genetic disease. That is different.

There are lethal genetic defects that kill before puberty. Always have been. Always will be. The problem is you have an extraordinarily limited understanding of how evolution works.

Now do a bit of research on Duchene's Muscular Dystrophy, a lethal, X-linked characteristic. Male fetuses spontaneously abort. Females are born with DMD.
a bit on DMD (http://www.mdausa.org/research/020304dmd_study.html)

That's just the first example. If you like, I can more directly address your misunderstandings about evolution. If you care to persist in this idiotic line of reasoning, I will simply pepper you with more examples that refute your preposterous claim. Your move.

Wrong! Terribly sorry Bill, but there's a gap in your knowledge of mammalian reproduction, and in it is the answer to how homosexuality arises and why it is not related (directly) to genetics.
Straw man. I never said homosexuality in mammals was caused by genetics. I have spoken only to homosexuality in Drosophila and to the various erroneous claims about evolution that have been made here.

No Bill, it doesn't. There are other mechanisms which come into play with regard to brain structure and function whose origin is not directly the result of genetic mutation.

There is no gay gene. There is however, a biological reason why homosexuality appears in mammals (in general) and humans (in particular)

Sorry garys_2k for sounding too precise about it. Perhaps you unused to definite answers when social scientists and others positively embrace ambiguity and, dare I say it, ignorance. The question of the origin of homosexuality has been polarised between genetics and environmental causes. However mammalian reproduction introduces a third reason which is biological in origin but which does not require a genetic precursor to happen.
Balderdash. If it is biological, it is genetic, sir. Stop with the lame proclamations and get to marshalling evidence.

Cheers,

arcticpenguin

27th March 2003, 06:23 PM

Originally posted by BillHoyt

Balderdash. If it is biological, it is genetic, sir. Stop with the lame proclamations and get to marshalling evidence.

I don't know what he's getting at, but there is the possibility of it being developmental; i.e. due to environmental influence at specific stages of growth.

All in all he sounds much too certain of himself on a topic where the science is not clear.

arcticpenguin

27th March 2003, 06:26 PM

Originally posted by Titananarchy

Wrong! Terribly sorry Bill, but there's a gap in your knowledge of mammalian reproduction, and in it is the answer to how homosexuality arises and why it is not related (directly) to genetics.

No Bill, it doesn't. There are other mechanisms which come into play with regard to brain structure and function whose origin is not directly the result of genetic mutation.

There is no gay gene. There is however, a biological reason why homosexuality appears in mammals (in general) and humans (in particular)

Put up or shut up. You say there are mechanisms and reasons but so far have refused to name any.

BillHoyt

27th March 2003, 06:27 PM

Originally posted by arcticpenguin

I don't know what he's getting at, but there is the possibility of it being developmental; i.e. due to environmental influence at specific stages of growth.

All in all he sounds much too certain of himself on a topic where the science is not clear.

Hi, A/P,

But those influences would be cultural, not biological. Frankly, this one is a pompous clown who is already past the limits of his knowledge. He'll have to do more than proclaim and gainsay to make any headway.

Cheers,

arcticpenguin

27th March 2003, 06:29 PM

Originally posted by BillHoyt

But those influences would be cultural, not biological.
Not necessarily, could be chemical and therefore biological. Influence of hormones in the womb, that sort of thing. Agreed on the other point.

BillHoyt

27th March 2003, 07:15 PM

Originally posted by arcticpenguin

Not necessarily, could be chemical and therefore biological. Influence of hormones in the womb, that sort of thing. Agreed on the other point.

Most of the fetal hormones are from the fetus itself, rather than from the mother. The placental barrier permits transfer of maternal steroidal hormones, but largely blocks maternal protein hormones.

Cheers,

Denise

27th March 2003, 07:19 PM

I read somewhere that the fetus is female before it is bathed in a certain hormone, I believe testosterone which causes the fetus to take on male secondary charactoristics. The baby was genetically XY before hand, but it's not clear how the hormones "know" which fetus to bathe the hormone with. Does this make any sense?

Denise

27th March 2003, 07:20 PM

Originally posted by BillHoyt

Most of the fetal hormones are from the fetus itself, rather than from the mother. The placental barrier permits transfer of maternal steroidal hormones, but largely blocks maternal protein hormones.

Cheers,

OMG! LOL! Read the post I just posted while you were posting! Looks like you answered my question! Cue twilight theme music....

BillHoyt

27th March 2003, 07:28 PM

Originally posted by Denise
I read somewhere that the fetus is female before it is bathed in a certain hormone, I believe testosterone which causes the fetus to take on male secondary charactoristics. The baby was genetically XY before hand, but it's not clear how the hormones "know" which fetus to bathe the hormone with. Does this make any sense?

Worshipful one,

I think you mean primary sexual characteristics. The adam's apple, deep voice, beard and ability to guzzle great quantities of bad beer are the secondary sexual characteristics. The hormones are triggered during the gonadal differentiation phase of embryological development. The genes for those hormones reside on the Y chromosome.

Cheers,

BillHoyt

27th March 2003, 07:31 PM

Originally posted by Denise

OMG! LOL! Read the post I just posted while you were posting! Looks like you answered my question! Cue twilight theme music....

Hmmm, you did mean twilight zone there and not some sort of romantic serenade? Shades of that other thread...

Cheers,

Denise

27th March 2003, 07:32 PM

Originally posted by BillHoyt

Worshipful one,

I think you mean primary sexual characteristics. The adam's apple, deep voice, beard and ability to guzzle great quantities of bad beer are the secondary sexual characteristics. The hormones are triggered during the gonadal differentiation phase of embryological development. The genes for those hormones reside on the Y chromosome.

Cheers,

Yep, you got me. I was thinking penis and testes which, of course, are primary.:D At least to most men anyhow from what I've heard.

Anyhow, is there any measurable differences attributable from testosterone on homosexual vs heterosexual males?

spoonhandler

27th March 2003, 08:16 PM

Can we consider the possibility that rather than one obvious mutation in one gene, the combination of more subtle differences is at work? Slightly lower or higher expression of any number of genes, slightly better or worse binding affinities on certain receptors and so on, would have no impact on the overall viability of the affected organism, but may change behaviour.

Also, for evolution to somehow eliminate a particular mutation/behaviour, there needs to be selective pressure. What pressures do humans face that would delete such a hypothetical gene or mutation?

DrChinese

27th March 2003, 08:20 PM

Originally posted by Drooper

Would not evolutionary theory preclude the existance of genetically caused homosexuality?

No, as already mentioned by others. You are focused on the fact that homosexuals don't reproduce. First, this is not a true statement. Second, the relevant question is "do people which the hypothetical gene repreduce"? which is entirely different.

Further, it is a mistake to confuse "evolutionary advantage" with the actual mechanisms of evolution (random mutation, natural selection) . There is nothing that requires the adaption to be "useful" according to a simple, easily understood and objective criteria. Many - if not most - mutations have no discernible benefit for the species. Obviously, some do.

However, I think the research on the genetic component of homosexuality leaves a lot to be desired. It is a bit hard to get at without a coherent theory of human behavior to work against.

Denise

27th March 2003, 08:39 PM

As I asked earlier in the thread, what kind of studies have been done in homosexual non humans? Do they reproduce usually? Why is it that the denser the human population, the higher percentage of homosexuals? Is that true in the animal kingdom as well?

Fade

27th March 2003, 09:39 PM

I am not a biologist. In fact, my knowledge of genetics is limited to three years (only) of various courses that are somewhat related to the topic.

I have never, in my entire life, thought 'hey, I want to have sex with men and alienate myself from a large portion of the population'

Not once. It wasn't a choice. So it must be something else.

Titananarchy

28th March 2003, 12:23 AM

Originally posted by BillHoyt
Straw man. I never said homosexuality in mammals was caused by genetics. I have spoken only to homosexuality in Drosophila and to the various erroneous claims about evolution that have been made here.

Bill, you were replying to my statements about mammalian reproduction. It is not a straw man to say that your statements that something can be biologic without having a direct genetic cause. You have made a statement that I believe to be false. I have not misrepresented your argument.

Balderdash. If it is biological, it is genetic, sir. Stop with the lame proclamations and get to marshalling evidence.

Cheers, [/B]

Absolutely, but later. I'm busy but I will try to return to this later today or tomorrow with evidence of how a biological difference can happen without a direct genetic cause in humans, and in a burst of keeping to the subject of the thread, how homosexuality (or come to think of it) heterosexuality arises in humans.

Cheers.

Shane Costello

28th March 2003, 03:16 AM

As someone with a growing knowldege of genetics, led me add my tuppence worth.

IMO it's going to be difficult to measure any genetic influence on sexual preference without having a reliable and reproducible measurement of the phenotype, in this case homosexuality. Neither is it likely that there would be a single gay gene, rather a number of genes expressed together would influence sexual preference one way or the other.

Homosexuality has been accepted and practised to varying degrees throughout history. AFAIK it was very prevalent among the ancient Greeks, but that it went hand in glove with heterosexual relationships. I'd imagine that with the advent of Christianity and the role played by the Church in Greek society that homosexuality was frowned upon. It's hard to see how genetics could have influenced this about change.

In some species only a few animals in a colony or wider group assume reproductive duties. Last week's edition of "New Scientist" did a feature on this, and I'll get back to it when I have time.

a_unique_person

28th March 2003, 04:08 AM

since humans are social animals, it could well be that we need the 'gays' to perform essential societal functions.

BillHoyt

28th March 2003, 06:01 AM

Originally posted by Titananarchy
Bill, you were replying to my statements about mammalian reproduction. It is not a straw man to say that your statements that something can be biologic without having a direct genetic cause. You have made a statement that I believe to be false. I have not misrepresented your argument.

I'm afraid you really put the dash in the balder again. Here is the exact exchange of posts:
Wrong! Terribly sorry Bill, but there's a gap in your knowledge of mammalian reproduction, and in it is the answer to how homosexuality arises and why it is not related (directly) to genetics.
Straw man. I never said homosexuality in mammals was caused by genetics. I have spoken only to homosexuality in Drosophila and to the various erroneous claims about evolution that have been made here.

I repeat again: I have not said homosexuality is caused by genetics. Your statement clearly implies I made a genetic claim about human homosexuality. I have not. I have attempted to shed light on what seems to be a common misconception about how selection works.

And on that point, before we go any further, are we agreed that your claim about lethal genes was in error?

Cheers,

Dymanic

28th March 2003, 06:31 AM

In some species only a few animals in a colony or wider group assume reproductive duties.
In haplo-diploid species like ants and bees, the non-reproducing members are acting in their best genetic interests by aiding their siblings, to which they are more closely related than they would be to their offspring.
It's not going to help to explain homosexuality in humans.

I'm curious about where this (1994) research ended up:

WASHINGTON (AP) -- Two Canadian researchers have found
a link between the number of ridges in fingerprints and male
homosexuality, adding to the theory that sexual orientation is
determined before birth.

Hall JAY, Kimura D.
Dermatoglyphic asymmetry and sexual orientation in men.
Behavioral Neuroscience 1994;
108(6):1203-1206.

These guys evidently studied only male homosexuals. Even if we establish that male homosexuality has a biologicalgenetic cause, I wonder if homosexuality among females will be traceable to the same cause.

arcticpenguin

28th March 2003, 07:40 AM

Originally posted by Titananarchy

Absolutely, but later. I'm busy but I will try to return to this later today or tomorrow with evidence of how a biological difference can happen without a direct genetic cause in humans, and in a burst of keeping to the subject of the thread, how homosexuality (or come to think of it) heterosexuality arises in humans.

Once again, you have all the answers, but fail to reveal them. Put up or shut up, troll boy.

BillHoyt

28th March 2003, 08:17 AM

Also, for evolution to somehow eliminate a particular mutation/behaviour, there needs to be selective pressure. What pressures do humans face that would delete such a hypothetical gene or mutation?

There are two parts to the "any homosexual allele should have been eliminated" hypothesis:
o the presumed homosexual allele is recessive
o homosexuals don't reproduce
The errant conclusion is: the allele should have been eliminated.

First of all, the second premise isn't universally true. Secondly, if it were true, it still would not effectively eliminate the homosexual allele. Directional selection would, at best, reduce the homosexual allele frequency to its mutation-selection equilibrium value -- the point at which the rate of new homosexual alleles being introduced by mutation equals the rate at which these alleles are being removed by selection.

Cheers,

phobos

28th March 2003, 09:11 AM

Originally posted by Denise
Why is it that the denser the human population, the higher percentage of homosexuals?

Hypothesis: it isn't. The percentage of _out_ homosexuals will be higher in a region of denser population. If I'm gay and living somewhere sparsely populated, I'm unlikely to meet out gays very often, I'm unlikely to be part of any gay community. I'm therefore going to be reluctant to come out myself.

On the other hand, if I'm gay and in a major city, I'm going to encounter other gays much more frequently. I'm going to realise that there's a whole gay subculture. Therefore I'm far more likely to have the confidence to come out.

If anyone in this thread is _actually_ gay... comments?

Denise

28th March 2003, 10:53 AM

Yes, phobos, I agree. That's why I was asking if that was also true in animal populations. Meaning that there would be an evolutionary advantage to homosexuality if the animals do not produce offspring.That is, if the population is getting to the point of not being able to be sustained by the habitat. But, alas, everyone is focusing on Titanpoint. :D Yet, I sit here in the chair with my hand up like Horseshack "OOh! OOh! OOh!":D

phobos

28th March 2003, 11:15 AM

Originally posted by Denise
Yes, phobos, I agree. That's why I was asking if that was also true in animal populations. Meaning that there would be an evolutionary advantage to homosexuality if the animals do not produce offspring.That is, if the population is getting to the point of not being able to be sustained by the habitat. But, alas, everyone is focusing on Titanpoint. :D Yet, I sit here in the chair with my hand up like Horseshack "OOh! OOh! OOh!":D

Ah! Quite possible, then. I could, in a saturated population, decide not to breed, and still benefit my genes by helping my relatives with the work of rearing their children. Genetically, every brother is as valuable to me as one of my own children, since they carry 50% of my DNA. A nephew is worth 25%, and a cousin 12.5%. Such a strategy would become worthwhile in a population crisis, where it makes sense to emphasise quality over quantity in the business of breeding.

It seems plausible that homosexuality might be the method used to switch an organism from breeder to supporter. Asexuality would be optimal, though, and this is the solution worker bees have arrived at. Maybe sex is too fundamental in the mammal, and so the quick-hack of homosexuality was good enough for evolutionary purposes?

This would also mean that homosexuality is a genetic contingency plan, and we shouldn't expect a clear-cut 'gay gene'. Any gene or genes for homosexuality would, under this model, only become activated as a result of environmental factors.

IANABiologist, however, and so I might well be talking out of my gaping goatse.

Denise

28th March 2003, 11:28 AM

Well, going way out there here....

What if the percentage of homosexual animals rises with maternal malnourishment? So, there is a population of animals that are competing for scarce resources, and, as a result, many of the animals are malnourished. It would be better for the population as a whole, because none of them are fully nourshed, to have less of a population next generation so that they fit into their habitat. It seems to me that animal homosexual has been noted in the wild because they do not reproduce. They don't have the peer pressure that humans have to be heterosexual. So, as a result of the malnourishment, the next generation has a higher percentage of homosexuals that will not reproduce. Yes, I know it's out there.

phobos

28th March 2003, 11:43 AM

Originally posted by Denise
Well, going way out there here....

What if the percentage of homosexual animals rises with maternal malnourishment? So, there is a population of animals that are competing for scarce resources, and, as a result, many of the animals are malnourished. It would be better for the population as a whole, because none of them are fully nourshed, to have less of a population next generation so that they fit into their habitat. It seems to me that animal homosexual has been noted in the wild because they do not reproduce. They don't have the peer pressure that humans have to be heterosexual. So, as a result of the malnourishment, the next generation has a higher percentage of homosexuals that will not reproduce. Yes, I know it's out there.

Let's take this line of thought further. What if things look REALLY bad? Suppose I've been born in a litter. Suppose food is dangerously short, and suppose that I happen to be the weakest of my siblings, the runt of the litter, the least likely to be a breeding success. What's my best strategy to preserve my genes?

Suicide.

If I die on the spot, then my brothers and sisters will have more food. If they have more food, then they'll have more success in propagating their genes, many of which are my genes which they share. Some of those genes will say 'if you're the runt of the litter and food is very short, drop dead.'

Is this sort of thing observed in the wild? Runts and sickly young just dropping dead for no particular reason?

ISTR there was something like this in Selfish Gene, but I can't remember exactly what. I shall look it up.

Denise

28th March 2003, 11:58 AM

It has been observed that animals will decide not to feed one of their offsprings. So I don't think suicide really enters into the picture.

phobos

28th March 2003, 12:22 PM

Originally posted by Denise
It has been observed that animals will decide not to feed one of their offsprings. So I don't think suicide really enters into the picture.

Wow. That's even more brutal. I had the mental image of noble self-sacrifice, whereas the reality is one where the parents genes say 'It's not worth your time and effort to feed that loser; let it die.' Selfish genes can be real _bastards_...

DrChinese

28th March 2003, 07:40 PM

Originally posted by Dymanic

I'm curious about where this (1994) research ended up:

quote:
--------------------------------------------------------------------------------
WASHINGTON (AP) -- Two Canadian researchers have found
a link between the number of ridges in fingerprints and male
homosexuality, adding to the theory that sexual orientation is
determined before birth.

Hall JAY, Kimura D.
Dermatoglyphic asymmetry and sexual orientation in men.
Behavioral Neuroscience 1994;
108(6):1203-1206.
--------------------------------------------------------------------------------

I consider it self-evident that the number of ridges in a person's fingertips does not determine their sexual preferences. Does anyone reading this disagree?

What may not be so clear is that even finding a statistical corelation would still not demonstrate the biological nature of homosexuality.

Many studies detect spurious relationships. Such studies have no scientific value. It is not true - as stated in the quote - that this study would add to the theory that homosexuality is determined before birth. Unless of course the study identified an independent variable which was properly studied with random samples of the population, causal mechanisms hypothesized, etc.

This is an example of what I consider bad science. A spurious relationship is reported because it is interesting or controversial, when in reality there is no scientific value. Believe it or not, there are literally an infinite number of spurious corelations available to be studied. Don't be taken in.

Dymanic

28th March 2003, 10:21 PM

This is an example of what I consider bad science. A spurious relationship is reported because it is interesting or controversial, when in reality there is no scientific value.
Thanks, Doc! (may I call you 'Doc'?)

That's more confirmation for what I had heard about those guys--that some of their work is considered... less than rigorous. I figure a skeptic's forum is a good place to air stuff like that out.

I consider it self-evident that the number of ridges in a person's fingertips does not determine their sexual preferences. Does anyone reading this disagree?
I would have assumed they were not suggesting that the ridges determine sexual orientation, but simply that the increased numbers in ridges occur more frequently among homosexual men (for whatever reason--I doubt they claimed to know that).

What may not be so clear is that even finding a statistical corelation would still not demonstrate the biological nature of homosexuality.
You're right--that isn't so clear to me. Can you expand on that? How else could we confirm a thing like that, if not on a statistical corelation of some type? I obviously haven't read their book, and I'm guessing you haven't either--but suppose they did identify an independent variable, etc.?

garys_2k

28th March 2003, 10:35 PM

Don't forget that a definition of homosexuality is also hard to nail down. One incident, a few, thoughts about it, maybe 10% of sexual experiences with a same-sex partner? What and who decides the lines between hetero, bi and homosexuality?

I suspect that these vague definitions will cause comparing studies or surveys to be very difficult.

JamesM

29th March 2003, 09:35 AM

Originally posted by Dymanic

How else could we confirm a thing like that, if not on a statistical corelation of some type?

Probably not a useful answer to your question, but two things to look out for in statistical studies:

1. Were the subjects assigned randomly to the different groups? You can easily do this, for example, when testing for the efficacy of drugs. One group gets the drug, the other gets a placebo. If you do this, and get a statistically significant result, you may reasonably state cause and effect, e.g. taking the drug makes you better. It can be argued that bad luck meant that healthier people were put in the drug-taking group, but that can be accounted for by tests of significance.

In a study of something like homosexuality, however, you can't assign people to the homosexual and non-homosexual groups. Even if you had some special ray-gun which turned people gay, you would probably run foul of ethics committees before getting your hands on the cash to carry out the experiment. Here, you can only do a retrospective study, and you can never be sure that there isn't some hidden variable at work that you've not identified. At best you can only say the correlation is suggestive, but you can't say what's a cause and what's an effect (maybe fingertip ridges can turn you gay?) - you may have two effects.

Of course, problems with causation vs correlation can also apply to randomised studies. If you have a plausible mechanism to take you from cause to effect, you're on much safer ground.

2. Were the test subjects selected randomly from the general population, or from some subset? If they weren't from the general population (which, let's face it, is extremely difficult to arrange), then strictly speaking,it's only valid to apply your conclusions to the population from which you sampled. However, in many cases, the results would be extremely suggestive in applying to the population as a whole.

DrChinese

29th March 2003, 02:20 PM

Originally posted by Dymanic

Thanks, Doc! (may I call you 'Doc'?)

I would have assumed they were not suggesting that the ridges determine sexual orientation, but simply that the increased numbers in ridges occur more frequently among homosexual men (for whatever reason--I doubt they claimed to know that).

I obviously haven't read their book, and I'm guessing you haven't either--but suppose they did identify an independent variable, etc.?

Call me Doc, sure (LOL).

The deal about the number of ridges is the spurious correlation. The existence of the spurious correlation is meaningless. For instance, is it "more" or "less" ridges we are expecting in gays? Neither, you say, it is just that if there is a relationship it proves the genetic basis of homosexuality. Not true.

This is the fallacy of the spurious correlation. It leads us to believe that even if we don't know what the "true" independent variable is, it must exist. But such is not the case. It is a trick, and you have to alert to catch it. Scientists make this mistake all the time.

Let me use a spurious correlation to prove that homosexuality is NOT based on genetics. If homosexuality is not genetic, then presumably it is learned. If I prove it is learned, then by the logic of the correlation with fingerprint ridges, it must not be genetic.

Suppose I prove that gays listen to Barbra Streisand's music. This correlation (made up, but plausible if you saw that Kevin Kline movie) would say that gays learn to like such music, just as they learn to be gay. This would be a spurious correlation - no scientific value.

Darat

29th March 2003, 03:55 PM

There is a interesting news piece in New Scientist

http://www.newscientist.com/news/news.jsp?id=ns99993008

A study of gay sheep appears to confirm the controversial suggestion that there is a biological basis for sexual preference.
The work shows that rams that prefer male sexual partners had small but distinct differences in a part of the brain called the hypothalamus, when compared with rams that preferred to mate with ewes.

...

INRM

29th March 2003, 05:51 PM

I have a theory, but it's that there are multiple factors which determine homosexuality.

I've seen many types of gays but these are the two most common.

The first type is the one you rarely see on TV. They're the ordinary looking gay guy, with no speech impediment (lisp) whatsoever. They look ordinary, and act normally.

The second type are the kind who are flaming gays. They act all feminine and have a lisp, and walk with their wrists limped. Rather than saying "Oh God" like an ordinary person would, they would say "ooh, goodneth!" while limping their wrist.

The second type is the most popular view of gays.

Now, some gays have gender-recognition issues too! The kinds who either act like women, or those who have sex-change operations (I've talked to one).

The second one have no gender recognition disorders; they know they're men, they're happy being men; they just like other men.

Now, it gets even more complicated because some straight men have gender-recognition disorders. A film on HBO called "Normal" was based upon this.

And there *are* men who like women who have undergone sex-change operations.

Some gays knew they were gay from childhood. And others discovered they were gay in their teens, either after their first sexual encounter, or after a few times when they just realized they didn't like it. That must suck.

That's another interesting issue.

I think there are varying degrees of homosexuality, just as if there are varying degrees of skin-color. I'm a bit tan myself. I'm not blank white, or pure-black, I'm right in the middle.

IIRC, there are seven different alleles for producing skin color...

I think there are multi-alleles for determining homosexuality.

Some of these alleles may ALSO play a role in gender recognition, as some gays ALSO act effeminate. A much higher-percentage than in straight men.

It's definetly a recessive trait.

There is a final factor: environmental-- I believe that in some cases the homosexuality trait surfacing outright is probabilistic... just as some people have fairly light-skin, but can get real-tan when the time arises.

I believe that the trait may not surface if the right "triggers" aren't set off. Could be temperature like in the fruit-flies, or it could be something different in human beings... It could be excessive stress, it could be being raised around people of an opposite gender.

There are some guys, even if they were raised as guys, would turn out straight no matter what. There are guys where if they were raised around girls they would turn gay... others would turn gay even if they were raised around men.

But whatever this trigger, or triggers are, we don't know what they are. When they are set off, however, homosexuality surfaces.

Some cases it might not be a slight homosexuality (like a slight-tan), it could be much more. Such that the person could be homosexual no matter what. And in some cases (extreme), the person can realize they are gay from the start.

Despite this, the gender recognition factor... not all gays have it. Some can be quite openly gay and not have any trouble figuring out what gender they are. Some do think they were born in the wrong body. Like a man in a woman's body. Or the other way around.

For the most part, this I should mention. All the people that knew they were gay from the start... they were probably all women. One might have been a guy, but that's it.

-INRM
P.S. If some of this stuff doesn't make any sense, it's because I'm really tired.

DrChinese

29th March 2003, 10:07 PM

Originally posted by Darat
There is a interesting news piece in New Scientist

http://www.newscientist.com/news/news.jsp?id=ns99993008

See above about spurious correlations. Unless there is a causal mechanism between the size of the hypothalamus and sexuality, it is a spurious relationship and has no scientific value.

I don't care what magazine reprints a study, it is evidence of exactly nothing. This problem is more common than you think. What is the hypothesized causal mechanism? Where is the independent variable? If you don't know what they are, how can you measure it? That is the criticism of these types of studies.

It is a joke really. It used to be that the standard for such studies was that you came up with a hypothesis with a causal mechanism - an independent variable - and then prepared a rigorous study to support or deny the hypothesis. Nowadays, that is too difficult for most scientists. So they measure a relationship between two things with no known cause and effect relationship - because it is easy. Then they say... hmmm, maybe there is a cause-effect relationship in there somewhere, let's do another study!

But guess what - no matter how many times the study is done, and no matter what the results, it will NEVER prove the hypothesis. Not if it is a spurious relationship, which can't be determined by the study itself.

BillyJoe

30th March 2003, 01:17 AM

Originally posted by phobos
If anyone in this thread is _actually_ gay... comments?

.

Phaycops

30th March 2003, 03:59 PM

Originally posted by garys_2k
Don't forget that a definition of homosexuality is also hard to nail down. One incident, a few, thoughts about it, maybe 10% of sexual experiences with a same-sex partner? What and who decides the lines between hetero, bi and homosexuality?

I suspect that these vague definitions will cause comparing studies or surveys to be very difficult.

This is what I want to know. Obviously, in fruit flies, it is obvious. But fruit flies don't have human emotions and needs, and certainly aren't exposed to human media :)

Consider the tendency of college-freshman-aged women to identify as "bisexual," fool around with some girls, and then go get married (to a guy) and have kids after graduation, never to look back. It has been hypothesized by lesbians I have known that one reason for this is that there's this human desire to be a part of a group, but is also reinforced by cultural messages saying that it's ok for girls to sleep together (it's just gross if it's guys :rolleyes: ). How coudl you possibly assign these girls to "hetero" or "homo" groups? If they were just "doin it to be cool," wouldn't this skew your study in some way?

And anyway, doesn't it seem more likely that in reality it's a combination of factors and not just one gene? But then, people don't like to hear that kind of thing. It's too difficult and doesn't sell newspapers :D

arcticpenguin

30th March 2003, 04:01 PM

Originally posted by Phaycops

Consider the tendency of college-freshman-aged women to identify as "bisexual," fool around with some girls, and then go get married (to a guy) and have kids after graduation, never to look back.
I have heard that at women-only colleges there is an acronym for this: LUG, lesbian until graduation.

K-W

30th March 2003, 05:41 PM

Just speculation on my part, but I think if/when we do get an answer to this question it will be that its a very complicated genetic/enviromental interaction, and that there are multiple causes of the behaviors we lump together has homosexual. I think that the behavior of Homosexuality could be brought out by genetics, by cultural practices, or by a particular enviromental history. If this is the case than finding any patterns in the behavior would be extremely difficult. It would explain exprimentation, and the many variations in sexual preference and behavior.

DrChinese

30th March 2003, 06:07 PM

Originally posted by K-W
Just speculation on my part, but I think if/when we do get an answer to this question it will be that its a very complicated genetic/enviromental interaction, and that there are multiple causes of the behaviors we lump together has homosexual. I think that the behavior of Homosexuality could be brought out by genetics, by cultural practices, or by a particular enviromental history. If this is the case than finding any patterns in the behavior would be extremely difficult. It would explain exprimentation, and the many variations in sexual preference and behavior.

Well said, I agree totally. Most analysis is oriented to demonstrating environment over genetics, or vice versa. Such a simplistic reduction of the mechanisms probably doesn't work for human behavior. It is the interactions of both one's environment and heredity which are fundamental to explaining what is observed.

Phaycops

30th March 2003, 06:17 PM

Originally posted by DrChinese

Well said, I agree totally. Most analysis is oriented to demonstrating environment over genetics, or vice versa. Such a simplistic reduction of the mechanisms probably doesn't work for human behavior. It is the interactions of both one's environment and heredity which are fundamental to explaining what is observed.

I completely agree. But it doesn't change the fact that people want easy explanations for things. They want to be able to say "Oh, hey, I'm gay but it's genetic so you can't deny me basic rights anymore," or whatever. The whole debate is tinged with politics and agendas, you know, just like global warming, etc. People with agendas don't like messy things like, oh, I dunno, reality, because it's difficult.

Soapy Sam

31st March 2003, 10:23 AM

Who knows? If something as complex as Thalassaemia can be genetic, why not? I can see how a gene that makes a person sexually active may spread, even if it goes wrong some of the time;- say it makes you wildly attracted (and / or attractive to) men. If it finds itself in a man, it is merely unsuccessful reproductively; in a woman it may more than make up for that. What if such a gene tended to be linked to multiple birth in females? Potentially advantageous in a food rich culture, probably lethal in most of human history.

If there is a situation in which genes for X are advantageous, then they will evolve. Now choose your scenario.

This sort of thing is testable. But who cares?
Is voting Socialist genetic? Dunno. Is it hereditary? Yes, to a significant extent. Human culture is tricksy.

Kiri

31st March 2003, 10:52 AM

Originally posted by a_unique_person
since humans are social animals, it could well be that we need the 'gays' to perform essential societal functions.

Someone did a standup bit about this- citing gays' necessity to a successful hetero date: you go to a hairstylist who's gay, a florist who's gay, you take her to dinner and the waiter's gay, you go to a show and the actors are gay... "Without the gays, straight people would NEVER get laid!"

I don't know how much of it is genetics, but I don't think it's a matter of choice; I WOULD agree that the incidence of homosexuality is "normal".

Kiri

31st March 2003, 11:30 AM

Originally posted by INRM
I have a theory, but it's that there are multiple factors which determine homosexuality.

I've seen many types of gays but these are the two most common.

The first type is the one you rarely see on TV. They're the ordinary looking gay guy, with no speech impediment (lisp) whatsoever. They look ordinary, and act normally.

The second type are the kind who are flaming gays. They act all feminine and have a lisp, and walk with their wrists limped. Rather than saying "Oh God" like an ordinary person would, they would say "ooh, goodneth!" while limping their wrist.

The second type is the most popular view of gays.

Yeah, but isn't that a case of people getting caught up in a cultural stereotype? The culture at large can't accept gays as "normal", so the image of the cartoonish "fag" is used to isolate and marginalize gays, out of heterosexual insecurity. The sad part is that some gays, out of a desire for acceptance, buy into the stereotype themselves.

Now, some gays have gender-recognition issues too! The kinds who either act like women, or those who have sex-change operations (I've talked to one).

The second one have no gender recognition disorders; they know they're men, they're happy being men; they just like other men.

Now, it gets even more complicated because some straight men have gender-recognition disorders. A film on HBO called "Normal" was based upon this.

And there *are* men who like women who have undergone sex-change operations.

I draw some distinctions between gays, transvestites, and transsexuals: they're not necessarily all one and the same:

Gays prefer same-gender sex. They may or may not dress in drag, but they know they're men and like it that way. They're far too fond of penises to want them removed.

Transvestites like wearing the other gender's clothes. They may or may not be gay- it's not exclusively a "gay thing". Lots of "closeted" cross-dressers are straight guys experimenting with their femininity, hoping their women understand.

Transexuals feel they got the wrong gender, and want to change. I knew one such person: wore dresses, liked guys. NOT a gay transvestite; this is a female person, regardless of the body she's in.

Dymanic

31st March 2003, 12:07 PM

Originally posted by Phaycops

I completely agree. But it doesn't change the fact that people want easy explanations for things. They want to be able to say "Oh, hey, I'm gay but it's genetic so you can't deny me basic rights anymore," or whatever. The whole debate is tinged with politics and agendas, you know, just like global warming, etc. People with agendas don't like messy things like, oh, I dunno, reality, because it's difficult.

You've got a finger pointing at a them there, but I fear the problem is worse than that.

Announcing results of any scientific study seems to draw people with agendas like stink draws flies. When what is being studied happens to be humans (or especially then), objective interpretation of results (or even unbiased collection of data) is, almost by definition, impossible. When it comes to what makes us tick, everybody has an agenda (in addition, there are limits to what types of experiments can be done using humans as subjects). So any progress has to occur in the face of these obstacles. Often, before we can adopt a new way--hopefully a better way--of looking at something, an old way has to be abandoned; one observation about human behavior that can be made with confidence is that we don't like to give up a simple, working hypothesis for something that forces us to grapple with more complexity.

Some of the new tools that have dropped into our hands during the last eyeblink of human history are shining light into places previously unseen, revealing things that may make some of us uncomfortable--so much so that we might argue that these are things we can never understand; perhaps even that some things would be best left unexamined altogether.

The Nature/Nuture debate is an old one, and it seems obvious that most aspects of human behavior are affected by both--we may turn out to be 'meat puppets' to a far greater extent than we would like to think, but even so, we will never be meat puppets that live in a vacume.

Determining the degree to which we are driven by genetic predispostition is one thing; deciding what the moral consequences of those findings are is another. The latter may prove to be the more complicated matter.

31st March 2003, 09:21 PM

Originally posted by Drooper
I've read numerous articles in the past on this question.

But the thing that occurs to me is:

Would not evolutionary theory preclude the existance of genetically caused homosexuality?

Ask to Patricio Elicer?

Titananarchy

1st April 2003, 01:33 AM

Originally posted by Denise
Well, going way out there here....

What if the percentage of homosexual animals rises with maternal malnourishment? So, there is a population of animals that are competing for scarce resources, and, as a result, many of the animals are malnourished. It would be better for the population as a whole, because none of them are fully nourshed, to have less of a population next generation so that they fit into their habitat. It seems to me that animal homosexual has been noted in the wild because they do not reproduce. They don't have the peer pressure that humans have to be heterosexual. So, as a result of the malnourishment, the next generation has a higher percentage of homosexuals that will not reproduce. Yes, I know it's out there.

It could be Denise, except homosexuality does not have a genetic cause, and so therefore cannot be "bred" out of the population via natural selection.

In humans, the rate of male homosexuals is around 1-3 %. This remains stable across populations, cultures and societies, which does strongly indicate its biological origin.

Arcticpenguin: I will start a thread with the biological explanation of homosexuality (and come to think of it, heterosexuality) soon. However i) I have some coursework related to my degree which requires much of my time ii) my wife is expecting our first child and there's a lot of preparation to do and iii) I'm having hand problems related to RSI.

Titananarchy

1st April 2003, 01:41 AM

Originally posted by DrChinese

[b]See above about spurious correlations. Unless there is a causal mechanism between the size of the hypothalamus and sexuality, it is a spurious relationship and has no scientific value.

I don't care what magazine reprints a study, it is evidence of exactly nothing. This problem is more common than you think. What is the hypothesized causal mechanism? Where is the independent variable? If you don't know what they are, how can you measure it? That is the criticism of these types of studies.

Wait around and you'll find out.

It is a joke really. It used to be that the standard for such studies was that you came up with a hypothesis with a causal mechanism - an independent variable - and then prepared a rigorous study to support or deny the hypothesis. Nowadays, that is too difficult for most scientists. So they measure a relationship between two things with no known cause and effect relationship - because it is easy. Then they say... hmmm, maybe there is a cause-effect relationship in there somewhere, let's do another study!

But guess what - no matter how many times the study is done, and no matter what the results, it will NEVER prove the hypothesis. Not if it is a spurious relationship, which can't be determined by the study itself.

Actually there is clear evidence as to what causes these changes and where and when. I begin to wonder if the real reason you write this is because you don't believe that sexual identity is biologically elided, and therefore every scientific study becomes for you an issue of denial against your prior beliefs.

BillHoyt

1st April 2003, 06:10 AM

Originally posted by Titananarchy
Actually there is clear evidence as to what causes these changes and where and when. I begin to wonder if the real reason you write this is because you don't believe that sexual identity is biologically elided, and therefore every scientific study becomes for you an issue of denial against your prior beliefs.

You've been making these assertions since 27 March, sir. Is it not long past time to marshall your evidence?

Cheers,

Titananarchy

1st April 2003, 06:35 AM

Originally posted by BillHoyt

You've been making these assertions since 27 March, sir. Is it not long past time to marshall your evidence?

Cheers,

Bill, if you read the bit above to Arcticpenguin, you'll see why its taking a little time. When I've got the thing together, then I'll stick it into a new thread and everyone can see it for themselves.

BillHoyt

1st April 2003, 06:49 AM

Originally posted by Titananarchy

Bill, if you read the bit above to Arcticpenguin, you'll see why its taking a little time. When I've got the thing together, then I'll stick it into a new thread and everyone can see it for themselves.

I did read it, sir. I've been waiting, sir. You're like watching paint dry, sir.

Cheers,

Fade

1st April 2003, 10:27 AM

If anyone in this thread is _actually_ gay... comments?

I am, and I already did.

It seems to me that many people don't understand what is going through a gay persons mind. As I said before, there was no choice in the matter. I grew up looking at men (and women actually) as objects of my desire. When I had hots for the teacher, it was for the female AND male teachers. When I had crushes on celebrities, it was the female AND male celebrities.

I never consciously chose what to feel. It was as basic and natural to me as my love of avacados. I grew up devoid of gay culture and gay influence, my mother and father never spoke of it (good or bad) until I outed myself. So, I had these feelings in a relative vacuum.

If I had a choice, I would be straight, and that is the simple truth for just about every gay person out there. Life is easier when you're straight. You get treated better when you're straight. It would be foolish to want to be gay. Yet, here I am.

And I would put transsexuals under another orientation entirely, it rarely has anything to do with homo/heterosexuality. Transvestites on the other hand rarely WANT to be women, watch To Wong Foo, Thanks for Everything, Julie Newmar to get a good handle on what drag queens actually think.

DrChinese

1st April 2003, 11:44 AM

Originally posted by Titananarchy

Wait around and you'll find out.

Actually there is clear evidence as to what causes these changes and where and when. I begin to wonder if the real reason you write this is because you don't believe that sexual identity is biologically elided, and therefore every scientific study becomes for you an issue of denial against your prior beliefs.

I think I have stated my beliefs clearly. I am 100% open to the evidence, if you care to offer any.

For the record: I deny that any relationship has ever been demonstrated between human homosexuality and genetics other than a spurious one.

If I am wrong, show me the independent variable. Show me the causal mechanism. Keep in mind that a relationship can be measured between any two observables, and that many such measured relationships demonstrate a statistically valid correlation. Such does not mean there is a cause-effect relationship.

For example, the purported link between hypothalamus size and homosexuality does not describe a causal mechanism because it does not state which is the cause and which is the effect. Think I am splitting hairs? It is not as simple as it seems. It would be perfectly reasonable to suggest that homosexuality causes a change in the hypothalamus size. That would certainly upset the applecart of asserting that homosexuality is genetically determined if the physical changes occur at a later time.

I am sorry if my standards seem high. But the fact is, such is the nature of the scientific method - to which I subscribe.

Titananarchy

2nd April 2003, 12:46 AM

Originally posted by DrChinese

I think I have stated my beliefs clearly. I am 100% open to the evidence, if you care to offer any.

For the record: I deny that any relationship has ever been demonstrated between human homosexuality and genetics other than a spurious one.

If I am wrong, show me the independent variable. Show me the causal mechanism. Keep in mind that a relationship can be measured between any two observables, and that many such measured relationships demonstrate a statistically valid correlation. Such does not mean there is a cause-effect relationship.

For example, the purported link between hypothalamus size and homosexuality does not describe a causal mechanism because it does not state which is the cause and which is the effect. Think I am splitting hairs? It is not as simple as it seems. It would be perfectly reasonable to suggest that homosexuality causes a change in the hypothalamus size. That would certainly upset the applecart of asserting that homosexuality is genetically determined if the physical changes occur at a later time.

I am sorry if my standards seem high. But the fact is, such is the nature of the scientific method - to which I subscribe.

Nothing wrong with high standards for evidence, but bear in mind that direct evidence in humans is (for ethical reasons) more circumstantial, but nonetheless compelling.

Please also note that I do not make the case that homosexuality causes changes in hypothalmus size, only that both sexual orientation and hypothalmus size have a common (biological) cause.

Again, I have got to travel to the West Coast of America tomorrow, returning Sunday. I will probably start a new thread towards the end of next week, when I have discharged my other responsibilities first.

BillHoyt

2nd April 2003, 05:00 AM

Originally posted by Titananarchy
Again, I have got to travel to the West Coast of America tomorrow, returning Sunday. I will probably start a new thread towards the end of next week, when I have discharged my other responsibilities first.

*yawn*

arcticpenguin

2nd April 2003, 07:15 AM

Originally posted by Titananarchy

Bill, if you read the bit above to Arcticpenguin, you'll see why its taking a little time. When I've got the thing together, then I'll stick it into a new thread and everyone can see it for themselves.
I have a devastating and foolproof set of evidence that the earth is actually flat, and I would post it here except that I'm too lazy. I am not, however, too lazy to make absurd claims. Go figure.

Titananarchy

2nd April 2003, 08:10 AM

Originally posted by arcticpenguin

I have a devastating and foolproof set of evidence that the earth is actually flat, and I would post it here except that I'm too lazy. I am not, however, too lazy to make absurd claims. Go figure.

So there is a difference between a skeptic and a cynic.

BillHoyt

2nd April 2003, 08:47 AM

*chirp* *chirp*

BillHoyt

2nd April 2003, 09:00 AM

Welcome back from our commercial break, sports fans. A quick recap:

3/27: (Titananarchy) "However mammalian reproduction introduces a third reason which is biological in origin but which does not require a genetic precursor to happen."

3/27: (BillHoyt) "Balderdash. If it is biological, it is genetic, sir. Stop with the lame proclamations and get to marshalling evidence."

3/28: (Titananarchy) "Absolutely, but later. I'm busy but I will try to return to this later today or tomorrow with evidence of how a biological difference can happen without a direct genetic cause in humans, and in a burst of keeping to the subject of the thread, how homosexuality (or come to think of it) heterosexuality arises in humans."

3/29:[Note: this would have been "tomorrow" - bh ]

4/1: (Titananarchy) "I will start a thread with the biological explanation of homosexuality (and come to think of it, heterosexuality) soon. However i) I have some coursework related to my degree which requires much of my time ii) my wife is expecting our first child and there's a lot of preparation to do and iii) I'm having hand problems related to RSI."

4/2: (Titananarchy) "Again, I have got to travel to the West Coast of America tomorrow, returning Sunday. I will probably start a new thread towards the end of next week, when I have discharged my other responsibilities first."

Tomorrow has come and gone. As has "soon," which is now replaced with "towards the end of next week." The excuse count, however, slowly rises in the east as he heads to the west. Even the beer and peanut vendors are now leaving the stands, and the maintenance guy is turning off the stadium lights.

Click,

Soapy Sam

2nd April 2003, 11:23 AM

Can't help feeling the "truth" about homosexuality, genetic or cultural , will be established by study of the phenomenon among non-human organisms. Certainly gets rid of the emotive associations.

Kiri

2nd April 2003, 12:16 PM

Originally posted by Soapy Sam
Can't help feeling the "truth" about homosexuality, genetic or cultural , will be established by study of the phenomenon among non-human organisms. Certainly gets rid of the emotive associations.

Studies with gay sheep, and so on? I doubt that would address the supposed cultural contributing factors... unless the LACK of such factors proves to be significant. Hm.

Ace_of_Sevens

2nd April 2003, 12:43 PM

My understanding is that things can be biological without being genetic. Handedness, for instance.

And it seems extremely doubtful that human sexuality is genetical determined. We'd see more clear links if that were the case. It's more likely gentically influenced like any number of other personality traits.

BillHoyt

2nd April 2003, 01:06 PM

Originally posted by Ace_of_Sevens
My understanding is that things can be biological without being genetic. Handedness, for instance.

There are suggestions that birth order plays a role in handedness in chimps (Hopkins & Dahl, 2001). Even within the context of these suggestions, Hopkins and Dahl found that "the genetics of their [the chimps'] handedness is very strong." Since they found about 30% left-handed chimps and since human lefties are far fewer they hypothesize that there is more cultural mediation in human handedness. This work, whose title I can't put my hands on (sorry) was published in Psychological Science Vol 12, No. 4.

Cheers,

DrChinese

2nd April 2003, 10:15 PM

Originally posted by Titananarchy

Nothing wrong with high standards for evidence, but bear in mind that direct evidence in humans is (for ethical reasons) more circumstantial, but nonetheless compelling.

Please also note that I do not make the case that homosexuality causes changes in hypothalmus size, only that both sexual orientation and hypothalmus size have a common (biological) cause.

1. "Circumstantial but compelling" - I am saying there really isn't such a thing in science. Could be coincidence. Ethical reasons do not enter into the equation when determining proof.

2. "both ... have a common (biological) cause" - that means - BY DEFINITION - that the relationship is spurious. If there were such an underlying common cause, you would need to identify it and measure it. Despite the apparent reasonableness of the results, they will not be valid. Period.

athon

2nd April 2003, 11:29 PM

The role of genetics in determining the functioning of an organism is one of the most abstract of all biological systems. The 'cause - effect' relationship is impossible to unravel.

What I tell my students is this - genes are like the blueprints for making a vehicle. A car can go fast, or slow, have massive torque or all the grunt of a squirrel. Over time, things happen to the car to change its performance. Ultimately a driver's free will will determine how fast the car goes based on circumstances such as weather, need for speed etc.

So Hitler was not a dictator genetically, nor an arsehole. He had the basic mechanisms there for leadership based on the essential emotions.

Is homosexuality genetic? The basic biochemical tools required are. But they are merely influential - a straight person may have the exact same molecular machinary but act differently.

It's looking more and more like a true chaos theory at work.

Athon

BillyJoe

3rd April 2003, 04:20 AM

Originally posted by athon
What I tell my students is this - genes are like the blueprints for making a vehicle. This sounds wrong, athon.

Blueprints are exactly what genes are not.
The blueprint for a vehicle tells you exactly how the vehicle should turn out

What about recipe?
A recipe is nearly always pretty vague. A pinch of this. A dash of that. Add some of this and a handful of that......

"Genes are like recipes for making cakes."

How does that sound?

Dymanic

3rd April 2003, 07:50 AM

Blueprints are exactly what genes are not.
The blueprint for a vehicle tells you exactly how the vehicle should turn out.

What about recipe?
A recipe is nearly always pretty vague. A pinch of this. A dash of that. Add some of this and a handful of that......

"Genes are like recipes for making cakes."

A recipe generally has two types of information; a list of ingredients, and some instructions for putting them together. It's easy to see a gene as a list of ingredients, but where are the instructions for putting them together?

Diogenes

3rd April 2003, 07:58 AM

Originally posted by Dymanic

A recipe generally has two types of information; a list of ingredients, and some instructions for putting them together. It's easy to see a gene as a list of ingredients, but where are the instructions for putting them together?

Since things do (usually) get put together correctly ( i.e.. one eye on each side of the nose etc..), can't we assume the instructions are there? Even if we haven't learned how to read them yet.

arcticpenguin

3rd April 2003, 08:01 AM

Originally posted by Ace_of_Sevens
My understanding is that things can be biological without being genetic. Handedness, for instance.

And it seems extremely doubtful that human sexuality is genetical determined. We'd see more clear links if that were the case. It's more likely gentically influenced like any number of other personality traits.
Handedness and cilia (http://www.nurseminerva.co.uk/handedne.htm)

Dymanic

3rd April 2003, 08:13 AM

Originally posted by Diogenes

Since things do (usually) get put together correctly ( i.e.. one eye on each side of the nose etc..), can't we assume the instructions are there? Even if we haven't learned how to read them yet.
Since we haven't learned how to read the instructions, how can we know how much flexibility in the assembly process is tolerable, or to what extent it may be influenced by external factors?

Diogenes

3rd April 2003, 08:22 AM

Originally posted by Dymanic

Since we haven't learned how to read the instructions, how can we know how much flexibility in the assembly process is tolerable, or to what extent it may be influenced by external factors?
We cant.. Yet..

And your observation is quite valid.

It is apparent that gene damage can result in improper assembly.. Thalidomide, comes to mind..

However, it is also apparent that certain degrees of damage can be repaired. It would seem to be comparable to ' error-checking-and correction' as it applies to computer memory, where the original code can be reconstructed, based on a series of check bits.

spoonhandler

3rd April 2003, 02:47 PM

Thalidomide's effect is not a result of genetic damage. Thalidomide suppresses functional pathways of proteins involved in formation of new blood vessels, the downstream effect of which is malformation.

However, your point, that damaged genes can lead to errors in assembly, stands.

BillHoyt

3rd April 2003, 04:05 PM

Originally posted by Diogenes
However, it is also apparent that certain degrees of damage can be repaired. It would seem to be comparable to ' error-checking-and correction' as it applies to computer memory, where the original code can be reconstructed, based on a series of check bits.

Interestingly, you're pretty close with the ECC analogy. The code is both redundant and degenerate. Recent research has suggested that the redundancies, in many cases, correspond with the most common transcription (copying) errors. In addition, there are built-in mechanisms to correct translation errors. Its a bit of a hodge-podge, but the various mechanisms serve together in error-checking and -correcting.

Cheers,

corplinx

3rd April 2003, 04:15 PM

I have been reading this thread and waiting to comment. Let me just say this, show me proof homosexuality is genetic and I'll believe you. To be honest though, I could care less what makes someone gay. I have a friend Bryan who is gay and the root of his gayness has never come into question nor have I deemed it to affect our friendship in any way.

The only thing I am remotely curious about is just why Tom Cruise is gay. Genetics, Choice, or Scientology?

BillHoyt

3rd April 2003, 04:16 PM

Originally posted by spoonhandler
Thalidomide's effect is not a result of genetic damage. Thalidomide suppresses functional pathways of proteins involved in formation of new blood vessels, the downstream effect of which is malformation.

spoonhandler,

If you're talking about the suppression of Fibroblast Growth Factor (FGF), its less closely directed to blood vessels than this post implies. FGF clearly mediates vascularization, but it more proximal effect here seems to be a general distalizing signal. With thalidomide, the FGF signals that say "hey, you cells here need to turn into fingers (or toes) now" doesn't get properly suppressed. So limb buds too early start to form hands and fingers or feet and toes. The net effect of this early distalizing signal is foreshortened, malformed limbs. Although I note the jury is still out on exact mechanisms.

Cheers,

Kiri

3rd April 2003, 04:47 PM

Originally posted by corplinx

The only thing I am remotely curious about is just why Tom Cruise is gay. Genetics, Choice, or Scientology?

Beause he's just too damn cute to be straight! :D

slimshady2357

3rd April 2003, 05:34 PM

Bill and AP, you do realize that Titananarchy is Titanpoint from back a few months, don't you?

I think there were lots of times he acted like a troll (hey, I think there are lots of times I act like a troll :D) but in general, I think he backed up his claims if dealt with in a civil manner.

Just give him the time and I think he'll come through with the goods.

Obviously I'm not speaking to the quality of the goods ;) But I don't think he's just running you around the yard for a giggle.

Sheesh, what am I doing here defending TP? :D

Adam

arcticpenguin

3rd April 2003, 06:01 PM

Originally posted by slimshady2357
Bill and AP, you do realize that Titananarchy is Titanpoint from back a few months, don't you?

Yes, but do I care? If it looks like a troll and it quacks like a troll, I'm going to treat it like a troll.

Do you understand that Bill and I are both biologists and that if there were a clear and accepted answer to the question of the origin of homosexuality, we probably would have heard about it?

3rd April 2003, 06:04 PM

Originally posted by Diogenes

We cant.. Yet..

And your observation is quite valid.

It is apparent that gene damage can result in improper assembly.. Thalidomide, comes to mind..

However, it is also apparent that certain degrees of damage can be repaired. It would seem to be comparable to ' error-checking-and correction' as it applies to computer memory, where the original code can be reconstructed, based on a series of check bits.

Um, I was under the impression that Thalidomide caused an unbalance of hormone/precursor/something that, when present at the wrong time, messed up limb formation.

I wasn't aware that it was "gene damage", in fact if I recall correctly, it's not, it causes a failure in the development process instead.

(edited to say never mind, somebody already got there, somebody who is much closer to the subject)

arcticpenguin

3rd April 2003, 06:08 PM

Originally posted by jj

Um, I was under the impression that Thalidomide caused an unbalance of hormone/precursor/something that, when present at the wrong time, messed up limb formation.

I wasn't aware that it was "gene damage", in fact if I recall correctly, it's not, it causes a failure in the development process instead.
Yes, Thalidomide-induced birth defects are developmental. They may occur if a pregnant mother takes the drug in her first trimester. http://www.thalidomide.ca/english/brochure2.htm The drug is safe for adults.

He chose a bad example.

slimshady2357

3rd April 2003, 06:21 PM

Originally posted by arcticpenguin

Yes, but do I care? If it looks like a troll and it quacks like a troll, I'm going to treat it like a troll.

Do you understand that Bill and I are both biologists and that if there were a clear and accepted answer to the question of the origin of homosexuality, we probably would have heard about it?

Yes, I was aware of both of your expertise in this area.

But do you really think he's going to come back with nothing, or something completely laughable?

I'm interested in what he's going to come back with (man, where is this faith coming from?). I can wait.

Adam

arcticpenguin

3rd April 2003, 06:24 PM

Originally posted by slimshady2357

But do you really think he's going to come back with nothing, or something completely laughable?

I'm interested in what he's going to come back with (man, where is this faith coming from?). I can wait.
Adam
If/when that happens, I can deal with it, and if he's got legit evidence I will acknowledge that. But claiming "I have proof but can't post it now" is behaviour indistinguishable from several forum contributors whom I do not respect and will not name.

Cheers,

spoonhandler

3rd April 2003, 06:53 PM

BillHoyt - although there's still debate about the mechanism, Stephens and Fillmore have a pretty good theory involving FGF-2, VEGF and IGF-I, but more importantly, the downstream element, alpha v beta 3 integrin, a cell survival signal for newly formed endothelial cells. I was looking into the possibility that thalidomide might be a good anti-angiogenic agent to use in renal cell carcinoma and found their paper very interesting. Some of my lines of inquiry followed their theory and confirmed the possible importance of beta 3 integrin in angiogenesis and/or tumour growth.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10799645&dopt=Abstract

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10661908&dopt=Abstract

And no, thalidomide is probably not effective as a single agent against renal cell carcinoma and could in fact very bad indeed. Bugger. Yes, I published this negative result.

Ace_of_Sevens

3rd April 2003, 10:22 PM

On handness:

From the article linked to above, it does seem to be genetically linked, but it's fairly common for identical twins to have different handedness, so it's not straight-forward.

corplinx

3rd April 2003, 11:39 PM

What I want to know also is if front-loaded studies are causing meme propagation. Most people have heard about "some study saying homosexuality is genetic". Are studies that "look for a genetic cause of homosexuality" that get reported in the press causing these memes?

I say this because I was perturbed by an article I read in a paper a few weeks back where critic reviewing the "Rawhide Kid" comic said that homosexuality was genetic and that was that. He went on to say that if "god made them that way" that it was "for a reason" and that we should accept it.

Of course, he can probably show me about as much evidence for genetic homosexuality as he can for proof of a deity. I just wonder why so many people believe there is proof of this genetic link out there.

Ace_of_Sevens

3rd April 2003, 11:55 PM

I'd also argue that justr because somethign is genetic doesn't mean it's okay in a moral sense. IIRC, genetic links have been shown for alcoholism and violent tendencies as well.

Not saying that homosexuality is wrong, just that this is a seperate issue from its cause.

BillyJoe

4th April 2003, 04:33 AM

Originally posted by Ace_of_Sevens
[Handedness] does seem to be genetically linked, but it's fairly common for identical twins to have different handedness, so it's not straight-forward. Perhaps they're identical mirror images?

Diogenes

4th April 2003, 04:52 AM

Originally posted by spoonhandler
Thalidomide's effect is not a result of genetic damage. Thalidomide suppresses functional pathways of proteins involved in formation of new blood vessels, the downstream effect of which is malformation.

However, your point, that damaged genes can lead to errors in assembly, stands.

Thanks for the correction on thalidomide...

The information that followed from others was very educational..

arcticpenguin

4th April 2003, 07:31 AM

Originally posted by Ace_of_Sevens
On handness:

From the article linked to above, it does seem to be genetically linked, but it's fairly common for identical twins to have different handedness, so it's not straight-forward.
My understanding is that if the cilia are spinning in the 'usual' direction, the result will be right-handedness. If the cilia are not spinning, then the result is a coin flip.

Tiime to bring out the anecdotes: I have 5 brothers. 3 of us are left-handed, 3 are right. All of my 4 sisters are right-handed.

DrChinese

5th April 2003, 07:15 PM

Originally posted by Ace_of_Sevens
I'd also argue that justr because somethign is genetic doesn't mean it's okay in a moral sense. IIRC, genetic links have been shown for alcoholism and violent tendencies as well.

Are you sure? I know there have been a number of studies of statistical correlations. If there is a genetic link, which gene is it? What is the test to determine an individual is at elevated risk for alcoholism?

I think this is what corplinx was getting at. Everybody "recalls" hearing it somewhere. Then you look, and poof! It's gone.

And please, don't bother showing me studies that "suggest" a link. Scientific evidence only, please. A study done by a scientist does not make it scientific evidence.

Dymanic

5th April 2003, 09:54 PM

And please, don't bother showing me studies that "suggest" a link. Scientific evidence only, please. A study done by a scientist does not make it scientific evidence.
Insisting on evidence is a good thing and all, but are the requirements for what does and does not constitute evidence ever met with absolute certainty?

Is it inappropriate to speculate at all simply because of the way speculations have of getting transformed into fact as they enter the popular media?

If a genetic link (to anything) exists, won't evidence of that tend to emerge somewhat gradually? Aren't we most often working with small pieces of a puzzle that tend to present themselves one at a time? I mean, how often are we actually able to flick on a spotlight, suddenly suddenly revealing in stark detail all the mysteries of some previously unexplained phenomenon?

DrChinese

6th April 2003, 09:17 AM

Originally posted by Dymanic

Insisting on evidence is a good thing and all, but are the requirements for what does and does not constitute evidence ever met with absolute certainty?

If a genetic link (to anything) exists, won't evidence of that tend to emerge somewhat gradually? Aren't we most often working with small pieces of a puzzle that tend to present themselves one at a time? I mean, how often are we actually able to flick on a spotlight, suddenly suddenly revealing in stark detail all the mysteries of some previously unexplained phenomenon?

Studies which purport to show "evidence" of a link by virtue of the statistical relationship they document are not really science. It is a lot like doing part of the work and not the rest of the work, because the rest of the work is too difficult.

Did you know that there is a positive statistical relationship between life expectancy and owning life insurance? (I.e. people who have life insurance live longer than those who don't, I'm not making this part up.) This would imply that life expectancy is related to your insurance salesman, wouldn't it? Obviously not. You can intuitively see that such a relationship is spurious.

The reason it is spurious is that no cause-effect relationship is offered by me to allow the base hypothesis to be tested. A hypothesis which states that the correlation is fundamental is avoiding the scientific requirements of theory development. Yet how is my evidence "suggesting" a link between life expectancy and the purchase of life insurance any different than other such studies which "suggest" a genetic basis for this or that?

The correct sequence would be to a) hypothesize a casual relationship; b) determine a test which could falsify that hypothesis; and then c) perform that test. If such was done, one would quickly determine that there are many easier ways to falsify the hypothesis (a) than to perform a study which loosely supports the hypothesis (c). Most statistical studies take the easy way out because measuring a relationship - usually without bothering to create a random sample or gathering a sufficiently large sample size, etc. - is pretty easy and it makes for great headlines in peer journals.

Certainly I agree that theory development takes time. But shortcuts - however well intentioned - do nothing but lead us in the wrong directions. There are statistic relationships between literally millions of putative factors - all totally spurious - yet which purport to show a statistically significant correlation as being "interesting", "worthy of more study", "highly suggestive", etc. It is sometimes difficult to see that measuring the relationship is not really science.

Dymanic

6th April 2003, 10:14 AM

Did you know that there is a positive statistical relationship between life expectancy and owning life insurance? (I.e. people who have life insurance live longer than those who don't, I'm not making this part up.) This would imply that life expectancy is related to your insurance salesman, wouldn't it? Obviously not. You can intuitively see that such a relationship is spurious.

The reason it is spurious is that no cause-effect relationship is offered by me
Does it have to be you that offers the cause-effect relationship? Suppose that it was you who discovered the statistical correlation, and it was someone else who offerred the explanation that life expectancy and life insurance are related because the individuals who have the foresight and the resources to purchase life insurance also tend to be more consistent about seeking health care and living healthy life styles? Is an explanation like that (even though it may actually be the truth) ever going to be completely testable--or falsifiable? Even when we are pretty doggone sure about something, we aren't ever absolutely sure, are we?
It is sometimes difficult to see that measuring the relationship is not really science.
Seems like it's at least pre-science or something. I see what you're saying, and I don't disagree, but I don't see a big problem with saying, "These are some of the things we think may deserve a closer look". It might even turn out that somebody else already has some data--how else are you going to know?

DrChinese

6th April 2003, 11:54 AM

Originally posted by Dymanic

Does it have to be you that offers the cause-effect relationship? Suppose that it was you who discovered the statistical correlation, and it was someone else who offerred the explanation that life expectancy and life insurance are related because the individuals who have the foresight and the resources to purchase life insurance also tend to be more consistent about seeking health care and living healthy life styles? Is an explanation like that (even though it may actually be the truth) ever going to be completely testable--or falsifiable? Even when we are pretty doggone sure about something, we aren't ever absolutely sure, are we?

Of course it doesn't have to be me. And someone else could have postulated the cause-effect relationship. But that requires a causal mechanism too, and that is what is missing in such studies. So in the case of the life insurance, a specific, testable mechanism would be put forth for review. I could test it, anyone could test it. It should have sufficient detail to be falsifiable.

In your hypothesis about life insurance, you are actually stating that there is no causal relationship between the measured variables. That is because the relationship is spurious. It is certainly possible that X is related to Y, and X is related to Z. But that does not mean that Y is casually related to Z in any way at all.

A simple example of that is the sex of two siblings. The sex of each siblings is determined by the father (X or Y passed down). Yet there is no correlation between the sex of the siblings themselves. You would never be able to use statistics to figure out what was going on unless the causal mechanism was set forth. Then you would know exactly what to test. Everything else is spurious.

You ask whether there are cases in which such studies might be useful, like pre-science. Sure, there are cases in which the study is useful. I don't dispute that. But you really won't know that tell later, will you? My position is simple: the study is not the fundamental science. You need more - a lot more - to make it science. Theory + Experiment = Science.

Dymanic

6th April 2003, 06:44 PM

In your hypothesis about life insurance, you are actually stating that there is no causal relationship between the measured variables. That is because the relationship is spurious. It is certainly possible that X is related to Y, and X is related to Z. But that does not mean that Y is casually related to Z in any way at all.

A simple example of that is the sex of two siblings. The sex of each siblings is determined by the father (X or Y passed down). Yet there is no correlation between the sex of the siblings themselves. You would never be able to use statistics to figure out what was going on unless the causal mechanism was set forth. Then you would know exactly what to test. Everything else is spurious.

That makes perfect sense to me now. Thank you for taking the time.