Mystery of Homosexual Behavior

[dmaiski]

Whereas, when a man gets into bed with a man - Nature is transcended - and gloriously outwitted! We say "Forget the ruddy genes, whey-hey, let's just have some fun!"

 

this made me smile, and is a good summary of why you would chose to be bi...

 

"a hole is a hole"

 

im not sure about people who are "forced" to become gay due to the mythical "gay gene", but personaly I chose who i like based on what I think would be enjoyable

[jp255]

Evolution has built a mechanism to ensure procreation

 

It seems to me that while our conscious minds may think we are having sex for pleasure, deep down we are having sex to procreate

Except one can effectively break the association between pleasure of sex and procreation, that evolution created, by using contraception, so that the probability of getting pregnant is practically 0.

 

Homosexual behavior, whether genetic, environmental, or cultural is of no particular benefit and simply exists because the mechanism for procreation is not flawless.

I'd agree that the mechanism is not flawless. There seems to be no obvious benefit to the behavior, but whether or not is has been under positive selection or not isn't clear.

 

Having an attraction sounds to me like it must be from something like a genetic or developmental cause, rather than a social cause.

 

How much do you think those can explain though? Attraction seems to be subtle and complex, could genetics/environmental factors ever explain why an individual finds some people more attractive than others?

 

 

This makes gay and lesbian sex a fairly logical by product

I don't see the logic in that reasoning.

 

im not sure about people who are "forced" to become gay due to the mythical "gay gene", but personaly I chose who i like based on what I think would be enjoyable

The choice aspect mainly stems from attraction I think, in that homosexuals are homosexual primarily because they are attracted to the same sex. I've heard people say that they feel as though they didn't really actively make the choice to be homosexual because they didn't choose to be attracted to indiviuals of the same sex and they couldn't change it even if they wanted it. I think when they say they were forced they mean they didn't have the choice to be attracted to the other sex. They might choose to participate in homosexual behavior but did they choose the underlying attraction to the same sex?

 

Whereas, when a man gets into bed with a man - Nature is transcended - and gloriously outwitted! We say "Forget the ruddy genes, whey-hey, let's just have some fun!"

contraception is the transcention? anyways, can't the underlying reason for the two men winding up in bed together be explained by some of evolutions other creations, attraction + pleasure of sex?

[overtone]

Whether or not benefits do or don't exist is not the important question.

The question of what to presume' date=' what is the likely state of affairs given Darwinian theory and observed reality, appears to be a significant concern in this thread - possibly the single most important relevant issue, to the OP.

 

We have a body of posts and posters apparently presuming that there are no significant Darwinian benefits to whatever the genetic component of homosexuality is eventually found to be. I am pointing out that the presumption should be otherwise, given our current state of knowledge.

 

In my opinion, the argument should not go beyond how likely it is that homosexual behanvioural traits confer selective advantages as there is no/very little evidence suggesting that there is or isnt. Assuming either possibility isn't appropriate as it is an open question whether there are or are not selective advantages.

To the extent that there are reproductive disadvantages - and the OP asserts them as the main source of the "mystery" of homosexuality.

 

to the extent that homosexuality has a genetic component - and its presence among all known human societies in recorded history argues for a least some factor not dependent on purely cultural factors alone - the OP claims this as a mystery, an odd and inexplicable circumstance contrary to Darwinian theory.

 

My posts have been in response to the OP, and the following discussion. If you wish the discussion to have been different, one in which no one is making such claims, then you have my sympathy. In this discussion, the observation that the indicated presumption about the Darwinian effects of homosexuality in intelligent, social mammals and birds (including humans) should be that there are some, and that they are significant, is perfectly appropriate,

 

and so far unaddressed by you, btw. This, for example, overlooks the major factors in the assessment:

When you say that you are not talking about a leftover from former times' date=' that is assuming that there is very high penetrance [/quote'] And that is the presumption I claim should be made - if any are made, and without them the whole thread evaporates - based on the ubiquity of homosexuality throughout recorded history.

and that a genetic component that contributes to homosexual behaviour cannot be found in an individual that reproduces.

Typo?

Proove the high penetrance or take back the statement.

I am not asserting high penetrance. I am asserting that it should be the presumption, in the OP of a thread like this, based on the evidence we have. The opposite, at least, should not be presumed, since it is highly unlikely given the facts at hand.

It is your perception that a homosexuality trait should in theory be wiped out from the gene pool very fast, but that might not be the case in reality.

My term was "apparent", duly qualified.

 

And: Maybe not, but such extreme unlikelihoods, such long shots, are not to be presumed for argument.

 

And: It is the case in theory, given the presumptions of the OP and the theory we have. If in reality it is not so, then we have something in need of explanation - in particular a correction in the OP, and new relevant facts, that show us where this standard but underinformed application of Darwinian theory has let us down.

 

Meanwhile, my point stands: if as seems likely (cultural, geographical, and historical ubiquity, cross cultural ineradicablity, physical and developmental occurrence ) homosexual behavior has an underlying genetic component; if as asserted it imposes at least some significant visible reproductive penalty; then: any presumption that this genetic component delivers no reproductive benefit capable of countering the asserted penalty is manifestly unlikely on Darwinian grounds. The presumption should be that it does, and that evidence and argument are required before presuming that it does not.

 

And has noted, we have no such evidence or argument.

[jp255]

In this discussion, the observation that the indicated presumption about the Darwinian effects of homosexuality in intelligent, social mammals and birds (including humans) should be that there are some, and that they are significant, is perfectly appropriate,

 

I have not addressed the question because there is no meaningful evidence to suggest homosexual behavior has been under positive selection. I presented the view that it isn't appropriate to assume there is a benefit, until there is supportive evidence. Would you say that all genetic disease alleles have reached the frequency they are at today because they confer selective advantage, by automatic presumption because they can result in survival/reproductive hits and so should have been eradicated long ago?

 

Yes, I didn't address that question, but we are not really in a position to address though.

 

And that is the presumption I claim should be made - if any are made, and without them the whole thread evaporates - based on the ubiquity of homosexuality throughout recorded history.

I don't understand why this presumption should be made, please explain.

 

that a genetic component that contributes to homosexual behaviour cannot be found in an individual that reproduces.

Not a typo, except i shouldn't have written cannot. If genetic factors which contribute to homosexual behavior are highly penetrant then those factors should be almost completely associated to individuals that display homosexual behavior, and therefore be fairly strongly selected against depending on how much of a hit to reproduction it causes.

 

if as seems likely (cultural, geographical, and historical ubiquity, cross cultural ineradicablity, physical and developmental occurrence ) homosexual behavior has an underlying genetic component

 

It is suggested that there are genetic components to homosexual behavior in humans, not because of those observations, but because of the estimated heritability from numerous studies.

[overtone]

I don't understand why this presumption should be made, please explain

Given the absence of any specific objection or counterargument, I am just going to refer you to the past two or three posts of mine, above, as they respond to the OP.

 

Would you say that all genetic disease alleles have reached the frequency they are at today because they confer selective advantage, by automatic presumption because they can result in survival/reproductive hits and so should have been eradicated long ago?

That is the standard presumption when considering ubiquitous, high frequency, cross-culturally extant and persistant, reproductive-age onset genetic disorders, yes. When inbreeding has been ruled out, etc.

 

Sickle cell is the famous one, but there are a few others. None as prevalent or directly influential (as the OP feels needs explanation) as homosexual orientation, but that level of indication is unnecessary - overkill.

[dmaiski]

http://en.wikipedia....social_behavior

"Sexual intercourse plays a major role in bonobo society observed in captivity, being used as what some scientists perceive as a greeting, a means of forming social bonds, a means of conflict resolution, and postconflict reconciliation."

 

humans aren't the only species that has discovered sex can be fun...

 

I turn your questions around:

 

why dose being "gay" necessitate a strict genetic cause, it can also be indicative of intelligence (in other words not being driven by basic biological programs), and freedom of choice

 

or it can be indicative of a deep rooted neuroses, or even some form of imprinting mechanism at work

Edited October 28, 2012 by dmaiski

[Appolinaria]

it can also be indicative of intelligence (in other words not being driven by basic biological programs), and freedom of choice

 

If someone believes they are only sexually attracted to the opposite sex, and "choose" to enter a sexual relationship with the same sex, then they are not only sexually attracted to the opposite sex, and that is not a conscious decision.

 

Perhaps your statement is true with some same-sex relationships who don't engage in sexual activity.

[overtone]

Homosexual behavior, whether genetic, environmental, or cultural is of no particular benefit and simply exists because the mechanism for procreation is not flawless.

That assertion requires serious evidence and argument. Meanwhile it is a pretty dubious presumption.

 

We have quite a bit of evidence against that presumption -

 

The historical, geographical, and cultural ubiquity of human homosexual orientation argues against a purely cultural origin and the lack of cultural benefit, both (there are some arguments out there for a predominant role in the founding of cities, trade empires, etc, for example).

 

The historical, geographical, and cultural ubiquity argues against a purely environmental origin - besides, environmental factors are culturally and genetically mediated, filtered.

 

The appearance of homosexual orientation during development in humans, the widespread occurrence of homosexual orientation among all known human populations, and its documented prevalence among many of the higher mammals and more social, long-lived, and intelligent birds, argues strongly for some genetic influence. That also indicates the likelihood - the presumption, unless disproven - of serious reproductive benefit inherent in whatever that genetic influence is. That would be basic Darwinian principle - features (including behavioral tendencies) that vary genetically between individuals and influence reproduction are under selection pressure, for or against.

[Chap]

Cannot homosexuality be the result of a recessive gene or set of genes surviving through the ages? Compare this with the case of an albino animal. In humans as well as in many other vertebrate species, there are several albino organisms existing within that species. They exist, even though they are at a disadvantage in the wild (obviously humans who have albinism are not at such a disadvantage because we don't live in the wild). Just like that, isn't it possible that the genes which may (directly or indirectly) lead to homosexuality be present within the human-gene pool, affecting only a small number of humans at a time, but present, nevertheless?

[jp255]

That assertion requires serious evidence and argument

 

I agree. Although, the point of it was that we currently have no/little knowledge of the benefits of homosexual behavior in humans. I still think you should apply this quoted response to your own statements.

 

The appearance of homosexual orientation during development in humans, the widespread occurrence of homosexual orientation among all known human populations, and its documented prevalence among many of the higher mammals and more social, long-lived, and intelligent birds, argues strongly for some genetic influence

 

Not sure why you keep saying that, when there is more meaningful suggestive evidence for a genetic basis in humans. Heritability studies.

 

That also indicates the likelihood - the presumption, unless disproven - of serious reproductive benefit inherent in whatever that genetic influence is

 

I strongly disagree. I don't think the liklihood is high enough to presume it. I think that the level of selection throughout history for homosexuality is a very important factor in this discussion, but unfortunately it is one which we have practically no information about. I'd take a guess that the level of selection might be a common contributor to people's opinion on this topic, and one which I think is possibly being assumed without much thought (by using observation about homosexuals today and applying it to history as well, and in overtone's case usage of darwinian logic). I'd think it inappropriate to assume that gentic loci which contribute to homosexual behavior will be selected against strongly, selected against weakly, neutrally, or positively. Consider them all!

 

You are using observational evidence to suggest that it should be standard to presume that homosexuality traits confer reproductive benefits, this does not need to be disproven as it can be trashed quite easily by simply asking you to provide real evidence for it (many theories can't be disproven but it doesn't make them true). Whilst you might presume that there is a benefit, you should also be willing to admit that there is an x% probability it is correct with x being totally unknown. Yes? if not, why.

 

Personally, I think that the importance of the historical selection is too great to assume it being this or that with no evidence. Depending on what assumption is made (high -ve selection, low -ve selection, neutral, +ve selection etc), I can imagine differeing conclusions will be produced. We don't know whether or not it has been under selection or whether or not it confers some advantage or disadvantage. You are simply eliminating possibilities using weak evidence, but what if homosexuality has largely risen in frequency due to it being a neutral trait? would you say that the hitchiker's thumb must be at it's prevalence today because of a survival/reproductive advantage? same question can be applied to anticlockwise hair whirl, ear wax, (insert any neutral trait). Did you know that neutral traits can rise in frequency too? if so, why is the possibility ignored.

 

This is what I suggest you do. Don't ignore genetic drift. Be very careful when considering historical selection for or against homosexuality. Consider all possibilities and question whether the particular behavior in question does contribute to some change in average number of offspring or not(is it really under selection -ve or +ve???). Don't place too much value in observation or the standard "it is prevalent so it must be beneficial" line of thinking.

 

Currently, we know of no benefits that homosexuality might confer to humans now or in the past. It isn't terribly logical to presume there are.

[overtone]

Although' date=' the point of it was that we currently have no/little knowledge of the benefits of homosexual behavior in humans. [/quote'] No, what I argue against was not that we have little evidence. What I argued against was the presumption in the OP - used as an assumption and the basis of an argument - that homosexuality has no reproductive benefits and in particular a net reproductive cost. I pointed out that all the evidence we have points to the opposite - if you don't want to make any assumptions at all, fine, but don't make the one the evidence counters, eh?

 

You are using observational evidence to suggest that it should be standard to presume that homosexuality traits confer reproductive benefits' date=' this does not need to be disproven as it can be trashed quite easily by simply asking you to provide real evidence for it [/quote'] As observed above by me, and kindly buttressed by you (you have been insisting all along that we have direct evidence for a significant genetic component to homosexual orientation, thank you), my "suggestion" is not subject to "disproof" in that manner. It is the counter proposal that is rendered dubious by the many factors listed above, the genetic component not least among them, and a simple application of Darwinian theory that would pass without question in almost any other context. You have not argued against the evidence by describing it as "observational", and you are not dealing with the argument by claiming it is based on nothing but "observational" evidence.

 

You are simply eliminating possibilities using weak evidence' date=' but what if homosexuality has largely risen in frequency due to it being a neutral trait? would you say that the hitchiker's thumb must be at it's prevalence today because of a survival/reproductive advantage? same question can be applied to anticlockwise hair whirl, ear wax, (insert any neutral trait). Did you know that neutral traits can rise in frequency too? if so, why is the possibility ignored. [/quote'] I don't ignore it, I deal with it directly - starting with the OP claim that homosexuality imposes a direct and visible reproductive cost. It is possible for homosexual geese, penguins, or people, to reproduce, but not to the extent they devote their time and resources to homosexual behavior - and so a larger percentage of homosexuals do not, and the rest do less, on average.

 

That is common observation, one made by every frustrated sheep breeder who found himself feeding a ram that wasn't doing its job with the ewes, every wannabe grandmother who watched the years pass with the attractive but unmarried son and no grandchildren arriving. If you really want to claim that homosexuality is reproductively neutral, like a hair whorl's direction, (but not like a hitchhiker's thumb or ear wax), I think you need the evidence and the argument, not me.

 

Currently' date=' we know of no benefits that homosexuality might confer to humans now or in the past. It isn't terribly logical to presume there are. [/quote'] Well, until you can come up with some kind of argument or evidence, you are asserting stuff that makes little sense. As argued above, in my posts, given the reality of homosexual behavior in mammals and birds and people, given the genetic component, it is in fact logical to presume that there are, unless and until we have evidence definitely demonstrating the contrary.

 

Such a presumption is a standard, right down the center line, Darwinian theory motivated approach. One of the great contributions of that theory is its capability of suggesting lines of research into counter-intuitive or overlooked reproductive benefits, in situations like this, beginning with the observation that there almost have to be some.

[jp255]

It is possible for homosexual geese, penguins, or people, to reproduce, but not to the extent they devote their time and resources to homosexual behavior - and so a larger percentage of homosexuals do not, and the rest do less, on average.

 

This is exactly the type of mentality I was warning against in my previous post! Using observational evidence you see today and then extending it to the whole of the evolutionary history of the genetic components of homosexual behavior. Is it really appropriate? I don't think it is. The level of selection for a trait can change over time, and I was not claiming homosexuality is neutral. I was merely suggesting that it is possible homosexuality might have been neutral or at least have a small cost to reproduction, and so might have risen in frequency randomly or by genetic hitchiking etc.

 

Consider cystic fibrosis, at very low frequency, individuals with CF alleles will have practically the same average number of children as the rest of the population as the probability of two carriers comming together is very low/0. As the frequency rises the strength of selection against it will rise however as the difference between CF carriers and non-carriers average offspring numbers will become larger. So in the beginning of CF it wouldn't have been under strong selection would it? most likely neutral. Maybe it has been only recently that homosexuality behavioral traits have had much of a reproductive cost. I'm just saying assuming the fixed cost to reproduction that you observe today and assuming it through out history is silly, what if the cost has been negligible for a long time such that the frequency could rise. Or what if throughout history the frequency of exclusive homosexuality has been non-uniform, and has been rare for a long time (up until recently)?

 

This mentality is quite common, there are quite a few threads like this. "How can homosexuality ever reach the prevalence it is at today when it has such profound effects on reproduction?". To me, you are just answering this question by assuming it is advantageous.

 

I don't even see the need to even try to attach advantageous or disadvantageous to genetic contributing factors of homosexuality. We only know of one or two loci which contribute, we don't really know the allele frequencies, we don't know how the frequencies have changed at the population level, we can't observe the nucleotide sequence changes. So we don't really know if the frequency of homosexual behavior is at a level which suggests there is an advantage or not.

 

Since your response suggests you assume there is a cost to reproduction. I'd like you to supply evidence that this cost has been there throughout history, such that an advantage to overcome this cost should be needed to explain today's prevalence.

 

Again, be very careful when you assume there is a cost to reproduction and that this cost has been present since homosexual behavior's evolution. Just because there might be a cost today does not mean there has been one since long ago, and observation of a cost today therefore might of little relevance.

[overtone]

Maybe it has been only recently that homosexuality behavioral traits have had much of a reproductive cost.

And similarly in penguins, geese, sheep, monkeys, apes, every human culture known throughout history and across the planet, and so forth.

 

This mentality is quite common, there are quite a few threads like this. "How can homosexuality ever reach the prevalence it is at today when it has such profound effects on reproduction?". To me, you are just answering this question by assuming it is advantageous.

No. You continue to mistake my entire argument. I am pointing out that assuming, without evidence, that there is no reproductive advantage, is not reasonable. I am arguing against a bad assumption already made, in the OP.

 

I am pointing out that on the basis of the evidence we have, which I listed, the reasonable assumption of the ones available would be that there is some significant evolutionary advantage to whatever the genetic basis of homosexuality is. As I said above, if you don't want to make any assumptions at all that would be just fine, but the OP does make an assumption in the matter, and it is not the reasonable one. That OP is what I was responding to, not some post claiming that we don't know enough about this matter to make assumptions.

 

Consider cystic fibrosis, at very low frequency, individuals with CF alleles will have practically the same average number of children as the rest of the population as the probability of two carriers comming together is very low/0. As the frequency rises the strength of selection against it will rise however as the difference between CF carriers and non-carriers average offspring numbers will become larger. So in the beginning of CF it wouldn't have been under strong selection would it? most likely neutral.

1) Cystic fibrosis is nowhere near as prevalent or widespread as homosexuality, in humans or anything else. It's the prevalence and universality that argues for the advantage, not the mere presence.

2) In point of fact, the genetic basis of cystic fibrosis has been researched with a view to discovering some advantage, which is deemed likely to exist - because it's perfectly reasonable to hypothesize an advantage, in such traits. It is difficult to account for their establishment otherwise, as the arithmetic of genetic drift or other available mechanism does not work very well even at the low frequencies and geographic isolation currently measured.

 

That is, it's reasonable (will get you grant money from competent evaluators) to presume such an advantage is likely even with the low frequencies and geographic/demographic isolation pockets characteristic of cystic fibrosis. Solid researchers have devoted much effort to clarifying the situation. http://en.wikipedia....ygote_advantage

 

It is not reasonable to simply assume, take for granted, as the OP pattern would have it, that there is no such advantage - even in a case like cystic fibrosis, much less something as prevalent and universal as homosexuality.

 

Again, be very careful when you assume there is a cost to reproduction and that this cost has been present since homosexual behavior's evolution. Just because there might be a cost today does not mean there has been one since long ago, and observation of a cost today therefore might of little relevance.

Of course. And you would have to be even more careful - much more careful, since you have no evidence or argument visible - in assuming no advantage to account for the apparent cost, the visible and verifiable cost, currently indicated by the evidence we do have.

 

So you join with me in objecting to the OP's assumption of such a net cost over an evolutionary time scale, based merely on the observation of its apparent nominal cost nowdays. We have agreement.

Edited November 13, 2012 by overtone

[jp255]

So you join with me in objecting to the OP's assumption of such a net cost over an evolutionary time scale, based merely on the observation of its apparent nominal cost nowdays. We have agreement.

 

I didn't really read much of the OP's posts. stopped after I read the curbing population suggestion. If that assumption was made, I'd agree.

 

The CF example was just to show that the cost to survival/reproduction is variable and can change depending on various factors, and that such a situation might be the case for homoseuality genetic factors. I was ignoring any advantages CF alleles confer.

 

 

Of course. And you would have to be even more careful - much more careful, since you have no evidence or argument visible - in assuming no advantage to account for the apparent cost, the visible and verifiable cost, currently indicated by the evidence we do have.

 

I'm not going to repeat my arguments, there has already been a fair amount of repitition. I was only trying to make you question the usefulness of any evidence of reproductive costs you are aware of, because if this cost to reproduction you see today hasn't been present throughout history then an advantage isn't required to explain the prevalence, is it?

 

I have not read any papers on this so I don't know how good the evidence is and whether or not it can be assumed that there has been a cost to reproduction since homosexuality began increasing in prevalence. Would you mind giving me some links to any papers that have information on how homosexuality impacts survival or reproductione rates?

[overtone]

I was only trying to make you question the usefulness of any evidence of reproductive costs you are aware of,

Something I quite clearly already did, and posted about repeatedly, from the beginning, right here.

 

because if this cost to reproduction you see today hasn't been present throughout history then an advantage isn't required to explain the prevalence, is it?

It has been present throughout history, as observed - you apparently refer to evolutionary time scale, not historical: and as noted above, you have no evidence or argument visible here that such is the case. It remains a theoretical possibility only, acknowledged but not supported. In particular, it is not something one can reasonably assume, base an argument on.

 

Meanwhile, there is plenty of evidence and argument that such is not the case (see above). Thus among the choices for assumption, the reasonable assumption, the one that agrees with the evidence and arguments we have: that some countervailing advantages exist, attendant upon the genetic basis of homosexual behavior - whatever that genetic basis, if any, may be.

[jp255]

It remains a theoretical possibility only, acknowledged but not supported

 

Yes, I said in my previous post I am not well read on this topic at all.

 

In particular, it is not something one can reasonably assume, base an

argument on.

 

Meanwhile, there is plenty of evidence and argument that such is not the case

 

If you have evidence for the cost to reproduction throughout evolutionary history then please post a link or citation, I'd like to read it.

Edited November 14, 2012 by jp255

[overtone]

If you have evidence for the cost to reproduction throughout evolutionary history then please post a link or citation, I'd like to read it.

My assertion is that the evidence we have points to a net reproductive benefit from whatever the genetic basis of homosexuality may be.

 

A net benefit, not a cost, is what I claim the evidence we have (inadequate as it is) supports. A benefit is what I claim is the reasonable assumption, if any such assumption is to be made. That would be the major point and motivation behind all my posting here. I'm not sure where the confusion is coming from.

 

As far as immediate reproductive costs of homosexual behavior, several are more or less obvious now and the reasonable assumptions for the past in any scale - the costs in time, energy, opportunity, and resources, for example, are sufficient to make the point, and currently visible in all homosexual taxa observed. Unless you are hypothesizing the absence of such costs in the past?

Edited November 15, 2012 by overtone

[jp255]

A net benefit, not a cost, is what I claim the evidence we have (inadequate as it is) supports. A benefit is what I claim is the reasonable assumption, if any such assumption is to be made. That would be the major point and motivation behind all my posting here. I'm not sure where the confusion is coming from.

 

As far as immediate reproductive costs of homosexual behavior, several are more or less obvious now and the reasonable assumptions for the past in any scale - the costs in time, energy, opportunity, and resources, for example, are sufficient to make the point, and currently visible in all homosexual taxa observed. Unless you are hypothesizing the absence of such costs in the past?

 

I understand that you are arguing for a net benefit. However I don't think your arguments are strong enough to presume a benefit and I don't think we have enough information to make such conclusions.

 

It isn't that I deny the existence of a cost, there is energy and time devoted to homosexual behaviors, it is that I am questioning the significance of them. How costly was/is homosexual behavior? Are the costs high or low when you consider the evolution of homosexuality traits (how much do they affect reproduction/survival rates)? I would agree that it would be likely that there is a benefit to homosexuality if one could demonstrate high costs throughout evolution of the trait. Though I wouldn't join you in assuming that the costs are such that advantages should be presumed to explain the prevalence.

 

I'm not sure that the observation of other species displaying homosexual behavior is evidence for a benefit in humans, we live in different environments and our fitness landscapes will probably be different. Not only that but the homosexual behavior is quite varied across all of the species that do display homosexual behavior.

[overtone]

However I don't think your arguments are strong enough to presume a benefit

This whimsical thought of your would have more effect if backed with some reasoning, maybe some evidence, something besides the bald declaration of opinion, relevant to what I posted.

and I don't think we have enough information to make such conclusions.

Then we are in complete agreement - as long as you also invoke those criteria against the OP assumption, which motivated the posting.

 

I would agree that it would be likely that there is a benefit to homosexuality if one could demonstrate high costs throughout evolution of the trait.

Or a low cost. Any cost, actually.

Though I wouldn't join you in assuming that the costs are such that advantages should be presumed to explain the prevalence.

Thepresent observed costs among mammals and birds, projected as plausible into the evolutionary past, are only one kind of evidence. The prevalence, distribution geographical and cultural and historical and familial, would be others.

 

I'm not sure that the observation of other species displaying homosexual behavior is evidence for a benefit in humans, we live in different environments and our fitness landscapes will probably be different.

True, humans could be some kind of bizarre exception, completely different, not at all subject to the common evolutionary patterns and presumed influences we take as normal in the hundreds of other taxa known to feature homosexual behaviors. But that's hardly the way to bet, eh?

[CuriousChris]

Epigenetics May Be a Critical Factor Contributing to Homosexuality, Study Suggests

The artical linked to above makes very interesting reading. The existance of homosexual behaviour is counter-intuitive. It should die out as a trait because it is unlikly to foster successful reproduction; a perfect selection pressure for natural selection to work on. The article posites that homosexual behaviour is caused by a faulty transmission of epigenetic markers from a father to daughter or mother to son.

 

Here is the key paragraph from the article.

 

The study solves the evolutionary riddle of homosexuality, finding that "sexually antagonistic" epi-marks, which normally protect parents from natural variation in sex hormone levels during fetal development, sometimes carryover across generations and cause homosexuality in opposite-sex offspring. The mathematical modeling demonstrates that genes coding for these epi-marks can easily spread in the population because they always increase the fitness of the parent but only rarely escape erasure and reduce fitness in offspring.

 

Interesting?

[jp255]

Thanks for that, definitely interesting. I wonder why you posted the article though. You should have just posted a link to the original paper, as that is always going to be more informative than a watered down summary (it is incorrect in places too, imo).

 

The potential involvement of epigenetics seems to be a possibility. I would disagree with the statement that the study "solves the riddle of homosexuality". This study does no such thing (not even close), but rather it proposes a new model based on suggestive evidence of epigenetics and transgenerational epigenetic inheritance.

Edited January 17, 2013 by jp255

[CuriousChris]

I've only made 4 posts still trying to find the ropes

 

This appears to be the originating work.

Homosexuality as a Consequence of Epigenetically Canalized Sexual Development

[overtone]

The existance of homosexual behaviour is counter-intuitive. It should die out as a trait because it is unlikly to foster successful reproduction; a perfect selection pressure for natural selection to work on. The article posites that homosexual behaviour is caused by a faulty transmission of epigenetic markers from a father to daughter or mother to son.

The problem there is the assumption revealed by the invocation of poorly supported "intuition" and the completely unjustified adjective "faulty".

 

The apparent discovery that sexual orientation is epigenetically influenced is interesting. The assessment that this influence is "faulty" in its normal, common, ubiquitous, and evolutionarily established workings is without support, and runs contrary to some obvious circumstantial evidence.

Edited January 18, 2013 by overtone

[CuriousChris]

The problem there is the assumption revealed by the invocation of poorly supported "intuition" and the completely unjustified adjective "faulty".

 

The apparent discovery that sexual orientation is epigenetically influenced is interesting. The assessment that this influence is "faulty" in its normal, common, ubiquitous, and evolutionarily established workings is without support, and runs contrary to some obvious circumstantial evidence.

Why is the word 'faulty' a problem? The epi-markers are normally swept away are they not? And homosexuality occures when they are not correctly swept away?

 

I don't think that the article does say the influence is "faulty" in its normal workings. What obvious circumstantial evidence?

 

I've read your post a few times and I'm not 100% sure I'm getting your point.

[jp255]

With regards to the "counter intuitive" comment you made, I do agree that it is unjustified and unsupported. Also the article made the statement "From an evolutionary standpoint, homosexuality is a trait that would not be expected to develop and persist in the face of Darwinian natural selection", which is not only terribly vague but also unjustified or supported. The original paper cannot be used as evidence to support these assertions in any way, the model is barely in it's infancy and there is no evidential support for the underlying hypothesised causes of homosexuality. Homosexuality and it's contribution to fitness isn't totally clear to me, if you have evidence to support the assertion please provide it.

 

 

 

The epi-markers are normally swept away are they not? And homosexuality occures when they are not correctly swept away?

 

you missed out an important word there "homosexuality might....", as I said the model is barely in it's infancy and there is no support for the model to be a true contributing cause.

 

I think the issue with the usage of the word faulty is that suggests that the epigenetic transmission is by mistake. That would be unsupported. The author's of the paper leave it at "escape epigenetic erasure", not commenting on the nature of the erasure.