A couple of questions about natural selection and our gene pool...

[infinix]

1. Natural selection doesn't seem to be operating anymore. Everywhere I look, the smartest and the brightest of the world are choosing to have less and less children while the pool of potential Jerry Springer show guests are growing like wild fire. What is going on here? I fear for our species...

2. On a somewhat related note. (Let me be clear that I'm not judging or assigning value.) A lot of people have advocated that being homosexual is a genetic predisposition rather than a choice. From an evolutionary standpoint, I don't follow that line of reasoning. How would the gene be passed on?

Let's suppose that before the society became more open, people who were homosexuals still got married and produced offspring to hide themselves. But now that more and more people are open and accepting of others' sexual orientation, what reasons/opportunities would the homosexuals have to pass on their genetic trait? The openly gay/lesbians would not be a part of our corporate gene pool

Am I missing something? I'm not out to bash or convert anyone, but I really don't understand how there would be a naturally occurring genetic dead end.

 

[6079SmithW]

1. Natural selection doesn't seem to be operating anymore. Everywhere I look, the smartest and the brightest of the world are choosing to have less and less children while the pool of potential Jerry Springer show guests are growing like wild fire. What is going on here? I fear for our species...

The effects of natural selection are highly diluted in a technologically advanced society like H. sapiens. Basically, our technology shields us from natural influences, an example being modern medicine, allowing many to live who were unadapted to, and would have died from, diseases.

Also, natural selection is a breeding game. Whoever can survive long enough to produce the most offspring wins. Intellectualism isn't neccessarilly selected for.

 

[JarodRussell]

2. On a somewhat related note. (Let me be clear that I'm not judging or assigning value.) A lot of people have advocated that being homosexual is a genetic predisposition rather than a choice. From an evolutionary standpoint, I don't follow that line of reasoning. How would the gene be passed on?

Evolution is only one factor. It is probably genetic. If it weren't, it would be just a decision by the individual, and that's not the case.

Now one could argue that nature has a fail safe mechanism that turns people with bad genes into homosexuals so that it's unlikely for them to reproduce. But I doubt that.

I think it's an error in the wiring. Reproduction is the main goal of life. Males/Females are supposed to react to the features of the opposite sex. Visual stimulation, pheromones, etc... homosexuals react to those from the same sex. Now if that's genetic or if it has something to do with very early childhood when all connections are being build, I don't know. I will probably again get burned for this, but there's no difference between a person being sexually attracted to the same sex and a person being sexually attracted to animals, or inanimate objects like cars. Something simply went wrong there, no doubt. If people should care about it is an entirely different question.

1. Natural selection doesn't seem to be operating anymore. Everywhere I look, the smartest and the brightest of the world are choosing to have less and less children while the pool of potential Jerry Springer show guests are growing like wild fire. What is going on here? I fear for our species...

Nobody said Jerry Springer show guests have bad genes and Nobel prize winners have great genes. Nuture vs. nature and all that...

 

[mari]

The genes for homosexuality (it's probably a combination of several) are likely recessive and can be passed on by straight siblings who carry only a single copy. Until the development of in vitro (by which lesbians can be impregnated) and surrogacy (by which gay men can have biological children), gay aunts and uncles could turn their resources to helping raise their straight siblings' children, thus ensuring that the nieces and nephews would pass along their genes.

Maybe there is some genetic benefit to being gay that we haven't figured out yet, that we would want these genes passed along. Maybe it's nature's way of attempting to limit the procreation of a resource-gobbling, planet-killing species. In other species, particularly ones where the females can reproduce without male assistance when males are rare, homosexuality is useful in procuring a partner to help raise the offspring. Humans obviously can't do that without a doctor's intervention, but maybe we used to, back in the ancient days, or maybe we're evolving toward getting rid of men.

 

[Robert Maxwell]

I think it's an error in the wiring. Males are supposed to react to the features of the opposite sex. Reproduction is the main goal of life. Visual stimulation, pheromones, etc... homosexuals react to those from the same sex. Now if that's genetic or if it has something to do with very early childhood when all connections are being build, I don't know.

To call it an "error" gives a value judgment to something that has no inherent, objective value. Evolution isn't goal-oriented in any way, and viewing it through the narrow lens of individual survival ignores that evolution also impacts group survival. There are species where the vast majority of members are sterile (like bees). Would you also call that an "error"?

Homosexuality arose because there were conditions that didn't select against it enough to weed it out of the genepool. In other words, it must have conferred some benefit toward group survival, and presumably there are a lot of carriers or it would not have propagated at all.

Remember that just because someone has a gene, it doesn't mean they will express it. Some genes are only expressed in combination with other genes. A "gay gene" has not yet been identified as far as I know, and it is most likely the result of a combination of genes, so having the genes passed on from generation to generation is not a problem.

 

[Jadzia]

1. Natural selection doesn't seem to be operating anymore.

It can't not work.

Everywhere I look, the smartest and the brightest of the world are choosing to have less and less children while the pool of potential Jerry Springer show guests are growing like wild fire.

Then the smartest and brightest don't have both the means and the will to reproduce. They are defective in that regard. Natural selection favours those who do have the means and the will.

2. On a somewhat related note. (Let me be clear that I'm not judging or assigning value.) A lot of people have advocated that being homosexual is a genetic predisposition rather than a choice. From an evolutionary standpoint, I don't follow that line of reasoning. How would the gene be passed on?

Homosexuality may not be genetically inherited; it may be caused by environmental factors (eg during mother's pregnancy, or exposure to things as a child, either social or chemical that affect how the brain/hypothalamus grows).

 

[infinix]

In other species, particularly ones where the females can reproduce without male assistance when males are rare, homosexuality is useful in procuring a partner to help raise the offspring.

What species exactly are you referring to? Typically, species that can procreate autonomously don't stick around to raise the offspring. They just lay a bunch of eggs and then either die or go on with their lives. They certainly don't look for another member of the species to help raise the second generation.

Homosexuality arose because there were conditions that didn't select against it enough to weed it out of the genepool. In other words, it must have conferred some benefit toward group survival, and presumably there are a lot of carriers or it would not have propagated at all.

This is closer to what I wanted to discuss. While we may not know the benefits of having homosexuals be a part of our gene pool, it is only logical to assume that as soon as the traits are exhibited, that particular genetic line ends. Whether the genetic trait is recessive or dominant doesn't really matter. If we say that a person is homosexual when the genes become dominant, then what logically follows is that the genetic traits which leads to the gene becoming dominant will not get passed on.

For example, having 6 fingers on your left hand is a dominant genetic trait. But it has been selected out of the gene pool so long ago that basically the entire population carries the recessive version of that gene. If homosexuality is genetic, then it should follow that pattern. Eventually, the entire population will be carrying the recessive version of the gene and there would be virtually no chance of that gene ever becoming dominant.

The only way the dominant homosexual gene gets passed on is if gays are actively trying to use surrogate moms to procreate and lesbians are actually getting pregnant just to have children. But most of the homosexual friends I have are simply content to be able to adopt a child. So it seems that the particular gene (or set of genes) will eventually become all recessive.

 

[Robert Maxwell]

^ You're still assuming homosexuality is caused by a single gene and I suspect the reality is more complex. We like the idea of single-gene explanations because it makes things so neat and tidy, but many genes only work in combination with other genes and specific environmental factors, so it's entirely possible that 90%+ of the population carries at least some of the genes related to homosexuality, and that the proper combination to express that characteristic only happens ~10% of the time.

Things get muddier when you start talking about bisexuals--that could be its own combination of genes/environmental factors.

The point is, the fact that these traits have persisted so long indicates it is not a simple matter of weeding a single gene out of the pool.

 

[JarodRussell]

I think it's an error in the wiring. Males are supposed to react to the features of the opposite sex. Reproduction is the main goal of life. Visual stimulation, pheromones, etc... homosexuals react to those from the same sex. Now if that's genetic or if it has something to do with very early childhood when all connections are being build, I don't know.

To call it an "error" gives a value judgment to something that has no inherent, objective value. Evolution isn't goal-oriented in any way, and viewing it through the narrow lens of individual survival ignores that evolution also impacts group survival. There are species where the vast majority of members are sterile (like bees). Would you also call that an "error"?

Sterile work bees have a specific function in the hive. Drones are not sterile, but they are not work bees (for instance drones also cannot sting). Queens are developed from a special selection of larvae that are specially fed in order to become mature. If a work bee was not sterile, then it would be an error. Heck, if a work bee was male, it would be an error. The word error btw does not give a value judgment, especially not in scientific context. An error is merely the difference between a data point and the defined norm (yeah yeah, I know, what's normal?!?!?!?rant?!?!?!).

 

[infinix]

Then the smartest and brightest don't have both the means and the will to reproduce. They are defective in that regard. Natural selection favours those who do have the means and the will.

How do we define someone as having the means to procreate? Simply having functional sexual organs or actually being able to effectively raise the next generation to be contributing members of the species? In the wild, those without the means to sustain their own survival do not get to procreate regardless of their reproductive organs. In our society, that is not the case. It is typically those without the means to sustain their own survival that tend to procreate the most.

I don't have a problem with people wanting to screw their brains out every chance they get. But please, condoms and other contraceptives can be had for free in most cases. When I was in college, RAs always had a stash of condoms. Nowadays, just about every high school, community center, clinic, and hospital will hand out condoms for free. USE THEM.

 

[farmkid]

Homosexuality may not be genetically inherited; it may be caused by environmental factors (eg during mother's pregnancy, or exposure to things as a child, either social or chemical that affect how the brain/hypothalamus grows).

To my knowledge, despite several studies to find one, no genes have yet been associated with homosexuality. I doubt it is genetic, as you state. It very well could be epigenetic, however.

For those not familiar with the term, epigenetics refers to marks on the DNA, either in the form of methyl groups added to cytosine bases or modifications to histones, that can change gene expression. There are some control regions in the DNA which can control expression from genes extending a million nucleotides in both directions depending on the methylation status of that control region. Those control regions can affect the expression of dozens to hundreds of genes and affect many different biological pathways without changing the sequence of the DNA. Looking solely at genetics--just looking for variations of genes--will completely miss epigenetic causes. During certain windows of time during embryonic development, those epigenetic marks on the DNA can be altered by the environment--by things the mother eats, is exposed to, etc. For example, if a mother does not provide enough calories to the fetus during embryonic development, certain epigenetic changes will be made to the fetus's DNA that will result in metabolic disease as an adult. That individual's body will improperly store energy as fat and the person will, on a normal diet, become morbidly obese and develop type II diabetes. It's entirely possible that something the mother is exposed to or some other event during pregnancy can make epigenetic changes to the fetus's DNA that will cause the person to be homosexual.

You are absolutely right in that homosexuality could be caused by something during pregnancy changing neural development. It very well could be inducing an epigenetic change, or it might just affect how the brain develops.

 

[TerokNor]

Well, not all what we become is only genes...enviroment plays a big role as well. So if the academics and co get less and less kids (the reason here is by the way often they women cannot get career and kids together, not enough nursery-places and that families in financial things are worse off)...so to have the "smart" getting more kids you have to work on these and other points.
The "not-so-smart ones" that get children are not always people, who are "genetically not smart", but people who grew up in an uneducated enviroment...so here soceity has to see, that these parents get the help they need (without unvaluing them and their parentship) so that they can raise the children to educated people.
Of course their also should be ways to help these adults to have hope in their future, to educate themself, to find a job and so on.
There are lots of "smart" people under the people who seem "not smart" they just never had the chance to develop their potential.
However as it is not done enough to help these families and to help all people to be able to have a family I do see why you have fears.

As for homsexual relationships... why should they not have children? Woman can look for a semen-donator and have children nontheless. Males can look for a lady, to get a kid for them, though its forbidden here I think, but allowed in other countries. Or they can adobt or foster care a child. Thats not their biological child then, but they can give it a good enviroment to grow up nontheless, so that this child becomes a "productive member of society" (I always hate to use that describtion...I know that society needs productive members as in working and so on, but it always sounds the way as if strongly handicapped people, who may not be "productive" in they way one understand productive are less valued, which is wrong and not what I mean.)

TerokNor

 

[infinix]

^ You're still assuming homosexuality is caused by a single gene and I suspect the reality is more complex. We like the idea of single-gene explanations because it makes things so neat and tidy, but many genes only work in combination with other genes and specific environmental factors, so it's entirely possible that 90%+ of the population carries at least some of the genes related to homosexuality, and that the proper combination to express that characteristic only happens ~10% of the time.

Things get muddier when you start talking about bisexuals--that could be its own combination of genes/environmental factors.

The point is, the fact that these traits have persisted so long indicates it is not a simple matter of weeding a single gene out of the pool.

True, homosexuality is probably not a single gene but a combination of various genes. But there must be something that triggers this combination of genes to become active and dominant. The general belief is that the trigger is more genetically based then environmentally based since homosexuals show up in just about every segment of the human race regardless of environment.

Given that, I fail to see how this trigger, which is genetically based, would be passed on.

 

[farmkid]

How do we define someone as having the means to procreate?

Generally, an individual is considered to have successfully reproduced when their offspring produce offspring. In other words, to an evolutionary biologist, you haven't successfully reproduced until you become a grandparent. This is because in some cases, an individual is able to produce offspring, but those otherwise normal offspring have a defect that makes them sterile.

 

[Robert Maxwell]

^ You're still assuming homosexuality is caused by a single gene and I suspect the reality is more complex. We like the idea of single-gene explanations because it makes things so neat and tidy, but many genes only work in combination with other genes and specific environmental factors, so it's entirely possible that 90%+ of the population carries at least some of the genes related to homosexuality, and that the proper combination to express that characteristic only happens ~10% of the time.

Things get muddier when you start talking about bisexuals--that could be its own combination of genes/environmental factors.

The point is, the fact that these traits have persisted so long indicates it is not a simple matter of weeding a single gene out of the pool.

True, homosexuality is probably not a single gene but a combination of various genes. But there must be something that triggers this combination of genes to become active and dominant. The general belief is that the trigger is more genetically based then environmentally based since homosexuals show up in just about every segment of the human race regardless of environment.

Given that, I fail to see how this trigger, which is genetically based, would be passed on.

I don't get it, what are you not understanding about the "combination" part? If most people carry some portion of the combination, then it's getting passed on by lots of heterosexuals. Yes, the full combination wouldn't typically be passed on, but if enough of it is surviving from generation to generation it's really not a problem--it will persist.

And if it's not entirely genetic but depends on certain environmental factors for expression (such as specific gestational circumstances) then you'll have people with the full combination of genes passing them on as heterosexuals.

Clearly, we don't know exactly what must happen for someone to be gay, but its continued occurrence at a significant level (~10% is hardly anything to sneeze at) is strong evidence that it is a genetically-resilient trait, being passed on by heterosexuals.

 

[Franklin]

1. Natural selection doesn't seem to be operating anymore. Everywhere I look, the smartest and the brightest of the world are choosing to have less and less children while the pool of potential Jerry Springer show guests are growing like wild fire. What is going on here? I fear for our species...

This is a spurious assumption on its own. Can you cite something to back it up? Statistics?

 

[Jadzia]

There are species where the vast majority of members are sterile (like bees).

That's an interesting example, which in a broader sense leads us to compare individualist vs collectivist societies.

In the latter case, we have a group organism, with the individual bees as the cells of that organism.

In a similar way, my blood cells do not reproduce, yet they exist to serve the whole collection that is my body.


If we assume that homosexuality has a genetic basis, and is stable in natural selection, we could hypothesise that it is supported to benefit the greater whole,
eg,

a) having more adults per child could nurture fitter children, or

b) specialisation (as with bees) into distinct roles (reproductive, supportive, intellectual, etc) that serves the whole group, far better than individuals could achieve as jacks-of-all-trades.

 

[Asbo Zaprudder]

1. Natural selection doesn't seem to be operating anymore. Everywhere I look, the smartest and the brightest of the world are choosing to have less and less children while the pool of potential Jerry Springer show guests are growing like wild fire. What is going on here? I fear for our species...

Translation: I ain't getting my share.

 

[RoJoHen]

^ You're still assuming homosexuality is caused by a single gene and I suspect the reality is more complex. We like the idea of single-gene explanations because it makes things so neat and tidy, but many genes only work in combination with other genes and specific environmental factors, so it's entirely possible that 90%+ of the population carries at least some of the genes related to homosexuality, and that the proper combination to express that characteristic only happens ~10% of the time.

Things get muddier when you start talking about bisexuals--that could be its own combination of genes/environmental factors.

The point is, the fact that these traits have persisted so long indicates it is not a simple matter of weeding a single gene out of the pool.

True, homosexuality is probably not a single gene but a combination of various genes. But there must be something that triggers this combination of genes to become active and dominant. The general belief is that the trigger is more genetically based then environmentally based since homosexuals show up in just about every segment of the human race regardless of environment.

Given that, I fail to see how this trigger, which is genetically based, would be passed on.

I don't get it, what are you not understanding about the "combination" part? If most people carry some portion of the combination, then it's getting passed on by lots of heterosexuals. Yes, the full combination wouldn't typically be passed on, but if enough of it is surviving from generation to generation it's really not a problem--it will persist.

Indeed. It seems like somebody needs Mendel to come give a refresher course in Inheritance.

Generations upon generations can carry and pass on a gene without that gene being active. But under the right circumstances and with the right pairing from your partner's genetic material, you can come up with the right combination to make all sorts of things happen. Homosexuality, while obviously more complex, is no different from hair color in that regard.

 

[RJDiogenes]

1. Natural selection doesn't seem to be operating anymore. Everywhere I look, the smartest and the brightest of the world are choosing to have less and less children while the pool of potential Jerry Springer show guests are growing like wild fire. What is going on here? I fear for our species...

This is true. Natural Selection is no longer a major factor in Human evolution. Medical Selection is a far bigger influence.

2. On a somewhat related note. (Let me be clear that I'm not judging or assigning value.) A lot of people have advocated that being homosexual is a genetic predisposition rather than a choice. From an evolutionary standpoint, I don't follow that line of reasoning. How would the gene be passed on?

It seems very likely that homosexuality is a fail-safe mechanism inherent in all Humans linked to population density. Other species of primates, in crowded conditions, will exhibit homosexual behavior (and some, like bonobos, don't bother to wait for crowded conditions ). In other words, everybody has the potential for homosexuality, but the likelihood of their expressing it is based on both the totality of their individual genetic structure and the specific circumstances of their lives. For example, someone with high potential may be triggered by being stuck in a crowded elevator as a child; others may have so little potential that they will never be triggered; others will have such a high potential that triggering is inevitable; others will have a balance of factors that lead to bisexuality. But the genetic potential for all this is carried in our common genetic heritage.