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Posted (edited)

Fair enough.

But the genes that are associated with homosexuality will continue to exist whether you believe in them or not.

 

Don't forget that it doesn't take a very high percentage of straight men to maintain fecundity in the group as a whole.

Plenty of men are happy to fill in for their brothers and cousins if those relatives don't want to sleep with women.

Also, plenty of women who prefer female company in bed still want children and may be prepared to accept that there are not many options for getting them.

 

Those are good points. But the whole basis for evolution is that he who sends his seed forward, wins. The fill-in's genes go into the next generation, and the homosexual's don't, in comparison. Some genetic crossover between the homosexual and his generous fill-in if a relative, perhaps .. but only if a relative. My argument is that most likely there aren't gay genes, that it's an error in the development of sexual preference, which must be very complicated to accomplish, perhaps by hormonal or other inconsistencies in the womb. Regardless, I don't think anyone has a choice in the matter of which body parts turn him or her on.

 

In case this wasn't clear, eusociality is a reproductive strategy whereby most members of the species do not reproduce themselves but care for the young of the breeding members of the species who are the brothers and sisters (or nieces and nephews or whatever) of the non-breeders. It is most commonly seen in hive and colony species, like ants and bees.

 

This isn't about socialization and empathetic responses to relatives. It's about an increase in reproductive fitness being achieved by members of the "family" failing to reproduce for themselves.

 

I understand that. Of course with ants and bees, the DNA of all individuals is so closely matched that evolution works differently than it does in most species. In humans, once you have a group of people, bonded together by empathy as well as self-interest, they will work out their own arrangements, and some of the participants will be those who for whatever reason are non-reproducers. Not every social arrangement is codified in our DNA; I think that a lot of general personality traits are set in our brains, and various versions of social interactions spring from that. For example, I doubt that communication by email and texting and cell phones is specified in our DNA.

 

Remember, not every couple is fertile; evolution isn't perfect in getting the plumbing exactly right in all of us. In the case of sexual preference, which presumably is hard wired in the brain and must be even more difficult to get right than the physical structure of our pee-pees, mistakes are going to be made from time to time.

Edited by CCWilson
Posted

"Those are good points. But the whole basis for evolution is that he who sends his seed forward, wins."

No. He who sends the best seed forward wins (in the slightly longer run).

 

"My argument is that most likely there aren't gay genes"

You are, I take it, aware of the evidence that says they do.

Obviously it's not a strict one- to one relation where "this variant of gene makes you gay and this variant doesn't". It's a combination of factors but it's simply absurd to say it's not genetic when the evidence is right there.

Posted

I understand that. Of course with ants and bees, the DNA of all individuals is so closely matched that evolution works differently than it does in most species.

Yes, but this ignores the fact that they had to evolve into that state. Their whole reproductive strategy Is reinforced by a sort of positive feedback loop of kin selection, but if kin selection didn't work they wouldn't have started down the path to eusociality and hyper-relatedness.

 

As far as success being defined as getting your genes passed on, let's back it up a generation.

 

Let's have two competing families with the patriarchs Adam and Steve.

 

Adam has five grown sons. Each son has two children. Each child gets resources from it's father and grandfather equally. Since there are ten children, that means each gets 50% of the total care output of one adult from their father and 10% of the total care output of an adult from their grandfather. Each child receives 60% of the total care output of an adult. Let's keep it simple and say that that's enough for 60% to survive to adulthood. Adam has 10 grandchildren, 6 of whome survive to adulthood.

 

Steve also has five sons, but Steve carries genetic material that can cause homosexuality, and two of his sons are gay. Each of his six straight sons has two children. That's six children and six caregivers (each child's father plus the grandfather and two brothers). Each child receives 100% of the care output of each adult, so all six children survive.

 

Now Adam and Steve have each managed to pass their genes on successfully to six children, however, Steve's grandchildren each received more resources than each of Adam's children and so are healthier and more likely to be able to care for their own children.

 

The "gay gene" present in Steve's two gay sons made them less reproductively fit, but Steve's ability to have gay sons increased his ability to produce fit descendants and therefore the fitness of his own genes.

 

Perhaps it is better to look at it not as a situation where having a gene that causes homosexuality increases your fitness, but having the gene that allows you to bear children who are gay as a small fraction of your offspring is advantageous, thereby perpetuating homosexuality on a genetic level.

Posted

"My argument is that most likely there aren't gay genes"

You are, I take it, aware of the evidence that says they do.

Obviously it's not a strict one- to one relation where "this variant of gene makes you gay and this variant doesn't". It's a combination of factors but it's simply absurd to say it's not genetic when the evidence is right there.

Actually, I'm not aware of any solid evidence that there are gay genes. I believe that periodically somebody announces such things, and then it turns out to be false. I'm certainly willing to change my opinion if there's substantial evidence of a gay gene. For me, it's illogical - but in science often the illogical turns out to be true, and a different logic makes sense of it.

 

Perhaps it is better to look at it not as a situation where having a gene that causes homosexuality increases your fitness, but having the gene that allows you to bear children who are gay as a small fraction of your offspring is advantageous, thereby perpetuating homosexuality on a genetic level.

 

Thanks for a thoughtful scenario. I don't doubt that having extra caregivers - and maybe more important, extra warrriors - could be of benefit to the survival of a family group. It's just that the balance between the benefit of having extra bodies in a family or group, which would perhaps indirectly carry some of the homosexual's genes forward, and the detriment to the homosexual's individual genetic legacy seems to me to be pretty heavily biased in favor of the genetic loss of any gay genes. If a couple has two or three sons, and they all are gay, their entire genetic heritage could be lost.

 

Incidentally, this argument mainly concerns men; I don't know that women, at the time these evolutionary changes were occurring, had much choice in avoiding pregnancy.

Posted

There are some fairly serious problems with group selection that may alter the path of this discussion: http://edge.org/conversation/the-false-allure-of-group-selection

That essay is arguing against a fairly specific use of the term "group selection" that I don't think applies to what we've been discussing. In fact, he even makes the following point:

 

"If a person has innate traits that encourage him to contribute to the group's welfare and as a result contribute to his own welfare, group selection is unnecessary; individual selection in the context of group living is adequate."

 

Which is more or less how I've considered group selection to work anyway.

 

Furthermore, the essay's discussion of eusocial insects makes exactly the same point I just did about self-sacrificing behavior being advantageous to the copy of the genes the caused it which exists in the "queen" or reproducing entity which birthed the self-sacrificer.

 

The only reference anyone in the thread made to group selection was an offhand comment by CCWilson that, as far as I could tell, wasn't really making a point about the genetic source of homosexuality one way or the other.

 

 

Don't get me wrong, it was a relatively interesting article, but I don't think it's going to change the course of this particular discussion much.

Posted

There are some fairly serious problems with group selection that may alter the path of this discussion: http://edge.org/conv...group-selection

I'm aware of that article by Steven Pinker, and the subsequent attack on E.O.Wilson's book, which promotes group selection, by Richard Dawkins. I haven't read Wilson's book - though I plan to - so I don't know which variety of group selection he believes in - but I'm a firm believer in a particular version of group selection, myself - though since I'm a layman, don't put too much stock in that. E.O.Wilson is a prominent biologist, so it's still an open question, although I think most evolution scientists don't accept group selection. Charles Darwin did, however.

Posted

Actually, I'm not aware of any solid evidence that there are gay genes. I believe that periodically somebody announces such things, and then it turns out to be false. I'm certainly willing to change my opinion if there's substantial evidence of a gay gene. For me, it's illogical - but in science often the illogical turns out to be true, and a different logic makes sense of it.

 

 

 

Thanks for a thoughtful scenario. I don't doubt that having extra caregivers - and maybe more important, extra warrriors - could be of benefit to the survival of a family group. It's just that the balance between the benefit of having extra bodies in a family or group, which would perhaps indirectly carry some of the homosexual's genes forward, and the detriment to the homosexual's individual genetic legacy seems to me to be pretty heavily biased in favor of the genetic loss of any gay genes. If a couple has two or three sons, and they all are gay, their entire genetic heritage could be lost.

 

Incidentally, this argument mainly concerns men; I don't know that women, at the time these evolutionary changes were occurring, had much choice in avoiding pregnancy.

As far as having all gay sons, there is, as mentioned, some evidence that the likelihood of being homosexual increases with the number of older brothers, which could theoretically be a mechanism for maximizing the benefits of being able having homosexual sons while minimizing the risks.

 

Incidentally, I'm not really arguing that homosexuality provides major reproductive benefits to a family, merely that there are enough potential benefits to balance the associated costs and allow for the maintenance of a genetic basis in the population.

Posted

An extra caregiver in a family is going to give a big boost in survival? Really? Come on, now! And on the other side of the equation, significantly reduced intersex copulation and offspring. And teenagers are programmed by evolution to rebel, most likely to prevent inbreeding, so many of them tend to leave the comforts of home and seek new adventures and new possibly like-minded friends, so you can't count on the family staying together. If you are Mr. Evolution Designer, taking all that into account, does homosexuality sound like a good idea? Um, let's see.

 

I specified that I didn't fall into the group selection camp, I was merely pointing out that your argument against it is much weaker than the argument itself. Who ever said evolution needs a big boost in survival? If only a small percentage of increase that small percent will grow as a whole were the other side wouldn't. A large boost is unnecessary. Why would you think teenage rebellion is programmed to prevent inbreeding when there are already psychological aversions to inbreeding to begin with? Where is the evidence that teenagers leave home for extended periods that would have an effect on this idea? Why would you assume something has to be a good idea for our thought process for evolution to use it?

 

 

It isn't a matter of morality, or whether homosexuality is a good thing today, it's just that all evolution is concerned with is the propogation of an individual's genes into future generations, and on that score homosexuality fails.

 

So does sickle cell anemia. But wait, a single recessive gene for that trait is beneficial in areas with high rates of malaria due to increased resistance. If the individual genes that, together, are involved with homosexuality have a negligible or positive effect on an organism it could easily come about.

 

 

I don't believe it is genetic. There may be a propensity that is genetically influenced, but I would say that is true for all things. I think sexual orientation is very much a choice, but for most it is probably not a choice that is easily altered.

 

So when did you decide the opposite sex sexually aroused you?

Posted
Why would you think teenage rebellion is programmed to prevent inbreeding when there are already psychological aversions to inbreeding to begin with? Where is the evidence that teenagers leave home for extended periods that would have an effect on this idea? Why would you assume something has to be a good idea for our thought process for evolution to use it?

 

I think teenage rebellion is built into our species somehow. When those hormones kick in, our parents, who seemed so wise and wonderful before, suddenly don't have a clue, and are almost evil in trying to control us. Now maybe this isn't related directly to evolution, maybe it's just some side effects of necessary changes, but on the other hand maybe evolution pushed the disatisfaction because it was useful. In what ways might it be useful? One would be to encourage breaking away from the family's ways of doing things, to try new solutions, to be creative rather than accepting the conventional way of doing things. Another would be to spread genetic diversity - which is very important - by encouraging the teenager to leave the family and seek fame and fortune, thus cutting down on inbreeding. I think there probably are innate psychological aversions to inbreeding, but I think it happens a lot in some families and communities, and if you're a horny brother, sister might be awfully tempting. I know that it happened frequently in some royal families. So the idea that teenage rebelliion might have come about because it was good for the species is just a guess on my part, but it makes sense. To be honest, most of the theory of evolution is based on guesswork and logic, in the absence of much solid scientific evidence. We can see evolution in action in bacteria and other simple organisms, but for homo sapiens most evolution happened long before science began, and we have to make educated guesses, supplemented currently by DNA studies, as to how things got to this point.

Posted

I think teenage rebellion is built into our species somehow....

You do realize that many species exhibit adolescent behavior like juvenile rebellion, it's not just us.

Posted
I think most evolution scientists don't accept group selection.

Many used to, but recent arguments have turned the consensus away from it fairly profoundly based on what I can tell.

 

All in all, the evidence all suggests that sexuality is very much predisposed by genes, regardless of what people personally choose to believe. You can choose your friends and choose your hobbies, but you can't choose your family or choose who you love. Why homosexuality may have evolved or survived is another question (that's also been answered elsewhere).

Posted

Many used to, but recent arguments have turned the consensus away from it fairly profoundly based on what I can tell.

 

All in all, the evidence all suggests that sexuality is very much predisposed by genes, regardless of what people personally choose to believe. You can choose your friends and choose your hobbies, but you can't choose your family or choose who you love. Why homosexuality may have evolved or survived is another question (that's also been answered elsewhere).

 

if you put it that way then people might not have to choose their hobbies, it can be genetic too when you think about it. Things you love to do whether its draw, play sports, men, women, etc. Still sources claim there is a gay gene others say there isnt, there are even gay people who suggest they chose to be gay.

 

 

 

Posted (edited)

...there are even gay people who suggest they chose to be gay.

I'm sure there are. While some people are genetically one extreme or the other there are going to be some in the middle without a predisposition one way or the other. Some choose to go one way or the other and some choose to go both ways. For those in the middle it is more of a choice than a natural disposition.

Edited by doG
Posted

I'm sure there are. While some people are genetically one extreme or the other there are going to be some in the middle without a predisposition one way or the other. Some choose to go one way or the other and some choose to go both ways. For those in the middle it is more of a choice than a natural disposition.

 

The distribution of sexual orientation is likely on a continuum, just more heavily weighted towards heterosexuality.

Posted (edited)

It has been suggested earlier in the thread that a family member who is unlikely to pass on their genes such as a homosexual person might have been of benefit to his/her family as a whole and in that way contribute to the gene pool.

I see this as a similar argument concerning the long post menopause life of human females - particularly grandmothers. There is an argument that the extra care these older people can give the family increases the survival rate of the grandchildren (who will in turn carry genes for longevity). So perhaps an element of extra care is important enough to be of benefit to the family's gene pool.

 

http://en.wikipedia....ther_hypothesis

Edited by Joatmon
Posted

The distribution of sexual orientation is likely on a continuum, just more heavily weighted towards heterosexuality.

Indeed. Here's the post to which I linked in the very first reply to this thread:

 

 

 

if you put it that way then people might not have to choose their hobbies, it can be genetic too when you think about it.

There's some validity to this point. Even though people are attracted to members of a given sex, they could still "choose" to have sex with people toward whom they're not attracted. A person attracted to the same sex could choose to have sex with an opposite sex person, just as a person attracted to the opposite sex could choose to have sex with a member of the same sex.

 

Likewise, we may be predisposed to prefer certain hobbies (skydiving versus stamp collecting, video game playing versus wood working, for example), but we could still choose to act contrary to our natural preferences and inclinations and choose a different hobby.

 

Where the comparison breaks down a bit is in the neuropsychological intensity of the preference. Sex tends to involve the reward and craving centers of the brain far more profoundly than something like gardening.

Posted (edited)

I agree. No one can consciously decide what turns him on, which sex he prefers to be intimate with. But he can indeed choose who to have sex with. I'm sure that many men with homosexual orientation in the past did confine themselves to sex with women - ugh! Now that homosexuality is more socially acceptable, we'll probably have more homosexual sex - but the desires and preferences will likely be much as always. Those who are halfway between homosexuality and heterosexuality in desire can choose to swing either way, or both ways, and godspeed.

Edited by CCWilson
Posted

My cousin - who I grew up around and is only 4 months older than me is gay. Were more like brothers than cousins though. I always knew he was a little different, being younger I would tease him but getting older and more mature, you just have to accept someone for who they are especially when you know they were that way since birth. I'm not going to lie when we had the talk where he confirmed to me he was attracted to the opposite sex, I felt really awkward. Even knowing my whole life, being confirmed that it was true was a very weird feeling. I thought about hugging him and it seemed almost different. After the initial shock and calming down, coming to my senses was a lot easier. That is my cousin who I'm going to love and support no matter what.

 

How I Knew he was homosexual - We would be in the back yard, playing pretend. Were fighting a monster so I tell my cousin about the shield, sword, and armor I have on. He usually started off by saying he was a girl. Why is that relevant when were fighting a monster at age 5? As we got older in elementary school it was obvious he felt more comfortable around girls. Well now its obvious, but back then it was weird. He was born this way.

 

Original posters opinion - I do believe that for some people, it is a choice. Although genes still probably have a lot to do with it. Growing up around someone who is gay, I got to see an individuals side of it. I can tell you that not everyone who is gay is by choice. It can be scientifically proven, it just has not been yet. They genetically engineered the aids virus to fight cancer. Theirs a lot about genetics that we are oblivious too, We have only scratched the surface scientifically of what our illusions allow us to grasp. Open your mind.

 

 

 

 

 

  • 1 month later...
Posted

Homosexuality is genetic. Definitely no question about that, there are multiple independent studies which have shown the heritability of homosexuality to be within the region of 30-60% (can't remember the exact value) and other studies which have shown the risk of recurrence between relatives being higher than control groups. To those who are saying it still has no genetic basis, explain why the studies are incorrect. That being said to say the environment has no effect, like one of the links I came across did, is not true. If it was true then the heritability would be 100%, but it is not. Homosexuality amongst monozygotic twins is also not 100% concordant.

 

So what genetic factors and environmental factors contribute to homosexuality? I think that there have been very few, if any, loci/genes which have been discovered to contribute to homosexuality in humans. I don't think the environmental factors have been looked into much either. Assuming that there is one gay gene is stupid, all possibilities should be considered. If anything it is more likely to be a polygenic trait because there are no discrete phenotypes, a range of preferences are possible. If you imagine there is a scale from 0-100, 0 being homosexual and 100 being hetero, I think it is safe to say there would be a range of values amongst populations from 0-100. This points to homosexuality being a complex trait, where there are many genetic and environmental factors which contribute to the sexuality value. How many factors there are is unknown. For other complex traits, like height, it is estimated that there are 100's to 1000s of contributing factors.

 

The way some have been thinking about the potential propagation of gay genes is not correct. "I can't see how a gay gene could survive" and other such comments. If you applied the same line of thinking to some genetic diseases you'd come to the same conclusion? that x genetic disease is not genetic? Some have been looking at survival of genes too closely at the level of the individual, saying the homosexual won't pass on his genes (this is not even true in all cases). This statement is wrong for two reasons, 1. the reason i just stated, some homosexuals do have children. and 2. brothers and sisters of the homosexual that do go on to have children will pass on their genes, and thus indirectly the homosexual passes on his genes because he and the sister share 50% of their genes on average. Sure if there was a 100% penetrant homosexual allele which accounted for all homosexulaity in a population then it would be weeded out fast, it is clearly not like that in reality.

 

To add to potential ways in which Homosexuality genetic factors can propagate and increase in frequency. Homosexuality is quite prevalent considering it reduces the individuals liklihood of reproducing. So how could genetic factors survive? one possibility is that some of the factors could have hitchiked to higher frequencies by being close to other genes which are under strong selection. If, for example, a genetic factor contributing to homosexuality was nearby a gene under strong selection such as brain size genes, then the homosexuality gene would increase in frequency despite the negative selection against it because of the more powerful positive selection of the nearby factor. Linkage disequilibrium allows for hitchiking to occur, although there is a limit to how long this effect will occur due to breakdown of the Linkage disequilibrium after recombination events over time.

Posted

It's possible that we're overlooking a factor - the human mind.

 

Our minds often make us do things that don't make sense genetically. Like caring for handicapped old ladies, who've long passed reproductive age. So they can't produce more babies to strengthen the community. Or help the community in a more passive sense - by looking after children. If the old ladies can't even do that, because of physical or mental enfeeblement, shouldn't we kill them off, and eat their flesh?

 

Perhaps mindless animals might do it. But our human minds recoil in abhorrence from the idea. Even if eating granny might be pro-survival.

 

We don't do such things, because our minds can override the programming of our genes. We have the freedom to do the opposite of what our genes try to make us do. The most spectacular example, perhaps, is consciously and deliberately committing suicide. Does any other animal do that? (Lemmings long ago bebunked!)

 

The point is, the human mind is not, despite Dawkins, just a computer programmed to control a survival-machine. We have broken free from our genetic programming.

 

And don't we rejoice in this freedom? It enables us to take pleasure in doing what Nature doesn't intend - in being "perverse".

 

As Edgar Allan Poe wrote: "I am not more sure than I breathe, that the assurance of the wrong or error of any action is often the one unconquerable force which impels us to its prosecution...resulting from the spirit of the Perverse. We perpetrate such acts, merely because we feel that we should not."

And this I think, is why gay sex has such a powerful attraction for humans. It appeals to us not despite the fact that it's perverse and against Nature, but precisely because it is.

So while the propensity to indulge in gay sex may have some somatic genetic component, a hormonal imbalance for example, I think it's mostly the product of an innate human impulse - to rebel against Nature, and take delight in doing so.

 

 

 

Posted

Note that even bacteria have altruistic behavior. Examples are fruiting body formations in which many bacteria give up the ability to reproduce so that others can form spores and pass on their genes. Also if we go down the "mind" route, it is still biology. Your mind is not something that works detached from matter. As such there is a genetic foundation on the plasticity that works on it.

Also cannibalism is not terribly widespread in many animals (although ritualistic cannibalism exists in humans). Likewise certain social animals do take care of their weak. So nothing terribly special in humans in that regard.

Posted

We don't do such things, because our minds can override the programming of our genes. We have the freedom to do the opposite of what our genes try to make us do. The most spectacular example, perhaps, is consciously and deliberately committing suicide. Does any other animal do that? (Lemmings long ago bebunked!)

 

Finding a few examples of animal who commit suicide is only a quick wiki away:

http://en.wikipedia.org/wiki/Animal_suicide

The point is, the human mind is not, despite Dawkins, just a computer programmed to control a survival-machine. We have broken free from our genetic programming.

 

I don't think that Dawkins had much input on our design during our evolutionary history. What's the evidence to say we have broken away from our genes because if you can give some there are many inherited diseases that you could take care of.

 

And don't we rejoice in this freedom? It enables us to take pleasure in doing what Nature doesn't intend - in being "perverse".

As Edgar Allan Poe wrote: "I am not more sure than I breathe, that the assurance of the wrong or error of any action is often the one unconquerable force which impels us to its prosecution...resulting from the spirit of the Perverse. We perpetrate such acts, merely because we feel that we should not."

And this I think, is why gay sex has such a powerful attraction for humans. It appeals to us not despite the fact that it's perverse and against Nature, but precisely because it is.

 

 

So I don't think you have bothered to read all the examples about how homosexuality isn't perverse nor is it against nature.

 

 

So while the propensity to indulge in gay sex may have some somatic genetic component, a hormonal imbalance for example, I think it's mostly the product of an innate human impulse - to rebel against Nature, and take delight in doing so.

 

So what you're saying is that it is genetically programmed, innate, for us to not be genetically programmed?

Posted

It is quite stupid to say that homosexuality is not natural when there are so many more instances of homosexuality than there are instances of homophobia in nature.

 

 

 

We have broken free from our genetic programming

 

 

 

I wish this were the case, I think you do too. However in this instance, it is more appropriate to lean more towards homosexuality not being a choice for a few reasons. Sexual attraction is, in many many animals, non-random. Genetic factors have been identified in many animals which alter preference of potential mates' traits. Most well known example of this is birds of paradise, but there are many other examples. So it is not such a stretch to think that sexual attraction in humans is also non-random. Although there are no genes which have have been discovered in humans which alter mate choice to date (at least none that I know of), There is evidence of non-random sexual attraction in humans by looking at the data from those dirty websites where users rate the appearance of people in the pictures shown to them. So there is more inclination to think that homosexuality is likely to not be a choice than the reverse.

 

 

 

Perhaps mindless animals might do it. But our human minds recoil in abhorrence from the idea. Even if eating granny might be pro-survival.

 

 

 

As charon said altruism is observed in many animals other than humans. Another point is that the comparison is ignoring other important differences. I think it is safe to say that most humans living in first world countries live in an environment where food, water and shelter are in plentiful supply and that there is a low probability that these basic needs will become difficult to obtain overnight. The same can not be said for the environment in which most other animals live. Do you think that we would still care for the old on the same level that we do today if we lived in an environment which was much harsher? where food, water and shelter were hard to come by? The cost of being altruistic is very small to humans in comparison to other animals and you are not taking this into account.

 

In my opinion, based on the sexual attraction arguments and it's subtle nature, I think there is an illusion of freedom and choice in this case which causes the heterosexuals to think that "homosexuals choose to be gay". Do you completely understand your own preferences concerning who you are attracted to completely? Why do you prefer black hair over blonde hair etc? If not, why do homosexuals have to be in complete control of who they are attracted to and therefore choose to be gay?

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