Homosexuality and 'Usefullness'

[Dancing David]

I am not sure this is sufficient to explain homosexuality in other species

Critters are driven to engage in sex. the gender may or may not matter. If you are driven to have sex and are not hardwired to have sex only with the opposit egender, they you will have sex. It is why female dogs hump male dogs and male dogs hump legs and toys.

 

[Dancing David]

I think you have to be very explicit and state what criteria you are using when you decide that some characteristic which has survived evolution is an advantage, a disadvantage, or neutral. For example, is bisexuality an advantage, a disadvantage or neither?

There is only one criteria, reproductive success, none other.

 

[Dancing David]

It wouldn't even have to be useful in an evolutionary sense. Perhaps one of the benefits of intelligence (if you can call it that) was the development of social pressures to keep people with homosexual tendencies reproducing. They may have always snuck stuff on the side, but still had their wives and husbands and kids.

The development of a sexually open and free society is really just within the past generation or so. In any case, legion, still, are the homosexuals who come out of the closet later in life, even to themselves, having already reproduced.

E.g. Ted Haggard, Larry Craig, et al.

I think presuming there must have been a valid (i.e. evolutionary) reason for homosexuality to develop may be missing the bigger picture that, for all human history but the very recent, they were functionally heterosexual "enough". The organism may have been gay, but the slightly larger organism that is gay biology + social pressure, functionally was not. Evolution doesn't care why you reproduce, only that you do. Gay biology (for no reason, or genetic drift, or god knows what) + social pressure is just fine with it.

Discussions about this are, unfortunately, hopelessly entangled with the politics, that, wrongly IMO, seems to demand people be "born this way" in order to justify their actions. That is technically irrelevant. In a properly defined society, The People never grant the government the authority to regulate adult sexuality. Hence questions like these are of purely academic interest.

Critters are driven to have sex, the gender is not a hard wired component in some animals. So the homosexuality is just a byproduct of the drive to have sex.

 

[ponderingturtle]

Pardon, but studies do show that altruism, via kin selection, may indeed be part of the cause of the retention of the genetic factors of homosexuality.

The last one requires a subscription, sorry.

So how do you get kin selection in non social animals? You would seem to need preservation of a family unit for that to make sense, and so would fail for most birds. I don't ever remember hearing about a brother bird hanging out with its siblings helping raise their chicks, but that would be interesting to see.

 

[ponderingturtle]

Critters are driven to engage in sex. the gender may or may not matter. If you are driven to have sex and are not hardwired to have sex only with the opposit egender, they you will have sex. It is why female dogs hump male dogs and male dogs hump legs and toys.

I agree but that is very different from those argueing for a evolutionary benefit for homosexuality.

 

[ImaginalDisc]

So how do you get kin selection in non social animals? You would seem to need preservation of a family unit for that to make sense, and so would fail for most birds. I don't ever remember hearing about a brother bird hanging out with its siblings helping raise their chicks, but that would be interesting to see.

Source

The museum said the exhibition, opening on Thursday despite condemnation from some Christians, was the first in the world on the subject. Soeli said a Dutch zoo had once organised tours to view homosexual couples among the animals.

"The sexual urge is strong in all animals. ... It's a part of life, it's fun to have sex," Soeli said of the reasons for homosexuality or bisexuality among animals.

One exhibit shows two stuffed female swans on a nest -- birds sometimes raise young in homosexual couples, either after a female has forsaken a male mate or donated an egg to a pair of males.

The genetics of altruism are strongest for kin-selection, but the articles I liked explained other sound mechanisms for the retention, and even promotion, of a theorized genetic component to homosexuality; It's clearly influenced by genetics, but the, ahem, penetrance, isn't 100%.


ETA: Oh, I'd forgotten about the gay penguins in the zoo. Behavior in captivity really isn't a good indicator of behavior in the wild.

 

[Hawk one]

With regards to our eyes, there is one thing I've wondered about, as I'll happily admit I'm still rather ignorant in the world of biology.

First of all, is it possible that we keep having the eyes we have simply because none of our ancestors ever got so lucky as to get himself two better eyes (I'll just keep using this term to cover all the things about our eyes), and then lived on to pass off those genes? After all, if the alternative never presents itself through mutation and genetic drift, then it doesn't matter whether or not it's a superior alternative, does it? Natural selection can only choose between traits that are already in existance, can't it?

And even if someone did get himself a better pair of eyes, if there is one thing I thought I had learned, it's that pretty much everything has a cost. Maybe developing and/or maintaining a better eye requires more resources, or it may be that some of the ways a better eye could evolve would mean a less stable copying of DNA sequences... Well, I'm expressing myself poorly, but I hope you get my meaning: That one really has to take a good, hard look at all possible aspects of a trait before one can even get close to make a judgement on what is better from any evolutionary view (whether it's "selfish genes", "punctuated equillibrium", or other variants).

Well, just some random thoughts, really.

 

[ImaginalDisc]

With regards to our eyes, there is one thing I've wondered about, as I'll happily admit I'm still rather ignorant in the world of biology.

First of all, is it possible that we keep having the eyes we have simply because none of our ancestors ever got so lucky as to get himself two better eyes (I'll just keep using this term to cover all the things about our eyes), and then lived on to pass off those genes? After all, if the alternative never presents itself through mutation and genetic drift, then it doesn't matter whether or not it's a superior alternative, does it? Natural selection can only choose between traits that are already in existance, can't it?

And even if someone did get himself a better pair of eyes, if there is one thing I thought I had learned, it's that pretty much everything has a cost. Maybe developing and/or maintaining a better eye requires more resources, or it may be that some of the ways a better eye could evolve would mean a less stable copying of DNA sequences... Well, I'm expressing myself poorly, but I hope you get my meaning: That one really has to take a good, hard look at all possible aspects of a trait before one can even get close to make a judgement on what is better from any evolutionary view (whether it's "selfish genes", "punctuated equillibrium", or other variants).

Well, just some random thoughts, really.

Evolution often leads to short-sighted half-measures, though Evolution obviously has no foresight. Traits, especially in animals, tend to be modified by very small increments, rather than by wholesale restructuring. Once an ancestral trait has developed, that trait tends only to be modified, or lost. That's why dolphins, bats, moles, and humans have such astoundingly similar forelimb bones.

A mutation that makes our crappy mammalian eye slightly better is much more likely to be passed on than any mutation that makes a huge change to it, such as sticking the vessels behind the eye, because so many other genes code for traits that depend on the first genes doing what it has done in the past. Even if that kind of mutation gave us an eye 50% as good as an octopus's eye, that would be an eye much worse than what we currently have, for the purposes which we use eyes. A blind spot is an obvious flaw, to our design-capable mind, but it's no enough of a hinderence for a malformed eye without a blindspot to persist. An eye without a blindspot just isn't enough of a benefit for it to be passed on because of the problems it would have.

 

[ponderingturtle]

Source



The genetics of altruism are strongest for kin-selection, but the articles I liked explained other sound mechanisms for the retention, and even promotion, of a theorized genetic component to homosexuality; It's clearly influenced by genetics, but the, ahem, penetrance, isn't 100%.


ETA: Oh, I'd forgotten about the gay penguins in the zoo. Behavior in captivity really isn't a good indicator of behavior in the wild.

I remembered the penguins but was wondering how common such a behavior would be in the wild. Female-female couples could well have chicks as there is plenty of infidelity noted in the avian community. The idea of egg donation seems a bit far fetched though.

But I am not sure that such a situation would be that beneficial, you could potentially double the number of chicks in a nest, but if that only meant the stronger survived it might not be bad.

 

[Dancing David]

So how do you get kin selection in non social animals? You would seem to need preservation of a family unit for that to make sense, and so would fail for most birds. I don't ever remember hearing about a brother bird hanging out with its siblings helping raise their chicks, but that would be interesting to see.

It is common in jays and crows if I recall correctly.

 

[Dancing David]

I agree but that is very different from those argueing for a evolutionary benefit for homosexuality.

Sibling rearing is one possibility.

 

[Hawk one]

Evolution often leads to short-sighted half-measures, though Evolution obviously has no foresight. Traits, especially in animals, tend to be modified by very small increments, rather than by wholesale restructuring. Once an ancestral trait has developed, that trait tends only to be modified, or lost. That's why dolphins, bats, moles, and humans have such astoundingly similar forelimb bones.

A mutation that makes our crappy mammalian eye slightly better is much more likely to be passed on than any mutation that makes a huge change to it, such as sticking the vessels behind the eye, because so many other genes code for traits that depend on the first genes doing what it has done in the past. Even if that kind of mutation gave us an eye 50% as good as an octopus's eye, that would be an eye much worse than what we currently have, for the purposes which we use eyes. A blind spot is an obvious flaw, to our design-capable mind, but it's no enough of a hinderence for a malformed eye without a blindspot to persist. An eye without a blindspot just isn't enough of a benefit for it to be passed on because of the problems it would have.

Yeah, forgot all about how you need to set it in context as well.

So, it seems to me that my point simply needs to be pushed back a bit. That I'll need to go back to the earliest stages of light receptors to speculate whether or not you at that point had the opportunity to later evolve "better eyes" (than what we currently have) some million years later. And if such mutations at those crucial early points never arised for whatever reason, then they obviously couldn't have been selected for, could they?

Sorry if this seems like I'm repeating myself. It's just one of those things I want to make sure I understand.

 

[ImaginalDisc]

I remembered the penguins but was wondering how common such a behavior would be in the wild. Female-female couples could well have chicks as there is plenty of infidelity noted in the avian community. The idea of egg donation seems a bit far fetched though.

Well, penguins often have large, populous, rookeries. Considering how incredibly dangerous every hunting trip is, and how many predators find penguins to be delicious, and the mortality rate of the penguins who remain behind as egg tenders, I have little doubt that numerous eggs become available as their parents die.

Assuming even a moderate rate of egg abandonment (by death of parents or otherwise) I’d hardly be surprised to find a significant portion of penguins to be homosexual. The parenting instincts of all the species are incredibly strong, so a mechanism for adopting stray eggs is already in place.

 

[ponderingturtle]

Well, penguins often have large, populous, rookeries. Considering how incredibly dangerous every hunting trip is, and how many predators find penguins to be delicious, and the mortality rate of the penguins who remain behind as egg tenders, I have little doubt that numerous eggs become available as their parents die.

Assuming even a moderate rate of egg abandonment (by death of parents or otherwise) I’d hardly be surprised to find a significant portion of penguins to be homosexual. The parenting instincts of all the species are incredibly strong, so a mechanism for adopting stray eggs is already in place.

Is that mode of breeding common in all penguins?

 

[ImaginalDisc]

Is that mode of breeding common in all penguins?

Chinstrap penguins, in whom homosexuality has been observed in captivity, do. All penguins except the Galapagos penguins do. They nest in caves and such, and I don't know how gregarious they are when nesting. Also, in the wild, female Chinstrap penguins have been observed to try to take offspring to rear from other females in order to rear them.

 

[Smiledriver]

Incidently I was trotting out Catholic arguments in an attempt to better explicate the 'useless' argument. It naturally falls on its face once you think about it a bit. There just more value in examining your opponent's argument in their own terms.

 

[Cuddles]

I think you have to be very explicit and state what criteria you are using when you decide that some characteristic which has survived evolution is an advantage, a disadvantage, or neutral. For example, is bisexuality an advantage, a disadvantage or neither?

One mistake you have to avoid is assuming a trait actually has survived evolution. Just because we see behaviour today doesn't mean it has stood the test of time. It could be a relatively new mutation that just hasn't had time to evolve away yet. This probably isn't the case with homosexuality, especially since it is seen in so many different species, but it is an important point to remember.