Can natural selection select for genes based on their utility at a group level?

[Martinus]

What the thread title says.

Does the theory of evolution allow for the possibility of certain genes being selected for not because they are necessarily beneficial to the individual, but because they are beneficial to the survival/well-being of the society/group in which such genes are prevalent?

The question is (as usual for me) motivated by the existence of homosexuality. Obviously, it is not a trait that would be genetically beneficial for an individual, and as such it should "die out" in the populace. However, it seems that the number of gay people is fairly constant.

So what if instead of the "gay gene" there is a gene that "procs" (for non-WoWtards, to "proc", in the context of an ability, is to occasionally produce an effect of some kind, instead of providing this effect on a permanent/constant basis) so that each fetus has some chance (let's say 10%) of being gay, due to some hormonal anomaly during pregnancy.

While such gene would not be useful at an individual level, at a society/group level there could be a benefit to a tribe/group in which certain part of the populace does not have kids, and thus can be expected/counted on to support their child-bearing brothers and sisters, and effectively dedicate more time and energy to the wellbeing of the society as a whole (an example of celibate clergy in many societies comes to mind).

Since in primitive/primal societies, the families were tribal, one can see why having such a minority would actually help the whole tribe survive, even though its individual members would breed less, on average, than another tribe where they were no childless people.

Thoughts?

[Strix]

I would imagine that reverse would be true if what you were saying is possible.

It is only recently in human history that over-population has become an issue. So, if what you are saying is true than it would be more likely that the "homosexual" gene would be turned-off so that off-spring would multiple better to insure survival of the species.

[Caliga]

If you're interested in this stuff, you ought to read Darwin's Radio.  Fascinating book.

[PDH]

If you believe that such a complex behavior as homosexuality is caused by a gene or other simple biological mechanism, rather than a complex bio-cultural interplay, you might as well believe what you want about evolution.

[jimmy olsen]

While not addressing the specific issue of homosexuality, natural selection can select for genes based on their utility at a group level? One only has to look at our level of empathy and generosity compared to the great Apes who are extremely selfish.

[Caliga]

Nonsense, Timmy, he shared all the time with Beegle Beagle. 

[Zanza]

Thoughts?

I think you seek a sense where there might be none. While it is well possible (or even likely) that homosexuality may be triggered by a hormonal anomaly during pregnacy it doesn't follow that this must have some kind of purpose. Homosexuality (just like life ) may just exist without a particular purpose.

[jimmy olsen]

Nonsense, Timmy, he shared all the time with Beegle Beagle. 

What?

[Caliga]

Nonsense, Timmy, he shared all the time with Beegle Beagle. 

What?

Grape Ape, Grape Ape. 

[Barrister]

So what if instead of the "gay gene" there is a gene that "procs" (for non-WoWtards, to "proc", in the context of an ability, is to occasionally produce an effect of some kind, instead of providing this effect on a permanent/constant basis) so that each fetus has some chance (let's say 10%) of being gay, due to some hormonal anomaly during pregnancy.

Never, ever make a WoW analogy when trying to discuss a serious topic.

The genetic term your looking for is a recessive gene, that only expresses when two such recessive genes are present.  The gene for sickle cell anemia is  the classic example.

[DisturbedPervert]

Plenty of gays end up reproducing. 

[Grey Fox]

Unlike BB, I approve of the WoW Analogy in a serious topic.

[Faeelin]

If you believe that such a complex behavior as homosexuality is caused by a gene or other simple biological mechanism, rather than a complex bio-cultural interplay, you might as well believe what you want about evolution.

I dunno. I think asking if homosexuality has an evolutionary role is kinda silly, because humans are the only species that has exlucislvey homosexuals. But it's pretty clear same-sex activities have an important role in other mammals.

More seriously... eh. The short answer is yes, the longer answer is still yes, but I'll have to dig up examples later.

[alfred russel]

Natural selection works on an individual level. However it can also work on a group level in certain circumstances--if group A has evolved to specialize in eating clams (perhaps a beak adoption within a bird species) and group B specializes in eating worms, if the clams of an area die out group A may go to extinction. That is even true if you are a member of group A and are a part of a minority that can eat worms, assuming there is little interbreeding.

What may be more complicated but a better explanation of an apparent homosexual / genetic link is that there is a complex series of genes that govern sexuality, and certain combinations can result in homosexuality. These combinations are almost certainly bad from an evolutionary perspective, but are maintained because similar combinations are advantageous. The possible oversimplified example of sickle cell anemia in african populations is an example: you have 2 sickle cell trait genes--one from each parent. If both genes have the trait, you will have sickle cell anemia and die. But if you have only 1 gene, you will have some protection from malaria and live longer than people with only normal genes. Thus a balance is reached where much of the population will have the trait where malaria is present, even if that means some must die form it.

Saying homosexuality is only genetic is almost certainly false, however.

[The Brain]

Does the theory of evolution allow for the possibility of certain genes being selected for not because they are necessarily beneficial to the individual, but because they are beneficial to the survival/well-being of the society/group in which such genes are prevalent?

Yes, obviously.