What evolutionary purpose does homosexuality serve?

Question

This is a follow-up to my last question: Does homosexuality exist because of intolerance?

So I am going to assume evolution works towards the benefit of entire species and individuals within that species do not have to procreate to obtain this, e.g. worker bees. I'm also going to assume evolution starts off with every animal for themselves and at some point they evolve beyond that; to where we have species collectively combining their own unique genetic talents together to form societies, instead of having every member of the species equipted with every possible positive trait.

If this is true we have to look at the definition of the human species in terms of our collective genetic traits and sociology, how we manage these traits. A genetic trait being something that must serve an essential purpose to be successfully developed over time, as opposed to a genetic mutation which just appears. What does/did homosexuality contribute to humanity in order justify its prevalence?

Answer 1

It could be a safety valve to prevent overpopulation.

Answer 2

You're wrong from the start. Modern evolutionary theory doesn't assume that evolution works toward the benefit of entire species. Tha's what Dawkins' "Selfish Gene" was all about.

Given that, though, there's no convincing argument I've seen as to why homosexuality wouldn't have been bred out of a population long ago.

Two possibilities:

It's not a genetic trait.

It's not directly beneficial but is associated with another trait or gene that is useful.

There's the same problem in trying to account for the persistence of schizophrenia.

Answer 3

Population control makes about ZERO sense. If the role of homosexuals, from an evolutionary standpoint, was to prevent overpopulation, since they will be less likely to reproduce, how in the world is the gene responsible for homosexuality supposed to get passed on to the next generation?

If their niche is to be the people who DON'T reproduce, how do their genes get passed on to create a new generation of homosexuals?

I honestly don't know what the advantage of being a homosexual serves, in the sense that I don't know what advantage that particular trait gives a member of a species.

It might be that a community's young benefit from a member who isn't burdened with children of his or her own. Still doesn't explain how the gene gets passed on, unless it's recessive. I suppose a recessive gene could potentially allow a family to produce a mix of hetero and homo children (though the homosexual children would probably be much rarer) so you have a mix of child bearers and primary and secondary child rearers. But this is all guesswork. I don't actually know. Maybe it's a common mutation that doesn't serve a purpose. Maybe our orientation is something that is particularly prone to alteration at some formative stage. Who knows?

I'm an archaeologist, not a biological anthropologist, so I'll stop now.

EDIT: the old dog: You seem to be confusing recessive genes with vestigial traits. The two are very different.

Answer 4

Homosexual behavior appears among numerous animal species, although it is seldom an exclusive sexual behavior in other species. For some, it seems that male homosexuality may be the norm during the greater part of the year, except for when females become sexually receptive. During what would conventionally be called "the mating season," males that would normally turn their attention toward one another redirect their energies temporarily toward fertile females. Later, the females are forgotten and the males resume their same-sex pairings. This would seem to serve the purpose of redirecting the attention of male animals when the female is pregnant, or rearing her young.

Other species, like the bonobo, practice a variety of sexual behaviors for a variety of social, not necessarily biological, purposes. Sex, sometimes same gender, sometimes opposite gender, provides bonding experiences, reconciliation, consoling, etc. I'm not sure that it is as easy to say that homosexuality contributes a biological benefit to the human species, but it may be possible to understand human sexuality as being far more complex than a mere biological process. Therefore, in any human sexual pairing, there are numerous issues; emotional bonding (love), psychological comfort, physical gratification, spiritual connections, economic trade-offs, etc. Simply put, where human beings are concerned, I believe that very little can be reduced only to biological considerations.

Answer 5

There are many instances of conditions which are carried in the gene pool which may not be initially apparent, but which do help the individual directly or indirectly.
From a purely scientific point of view, if we assume that homosexuality is an inherited condition, then perhaps it is the homozygous state of a yet unknown condition which benefits the individual or protects him/her in the carrier (heterozygous state), much like sickle cell trait (heterozygous) protects the heterozygotes from malaria, while the homozygous sufferers may well die young in life. Similarly with thallassaemia.
Such a scenario, if it existed, would be one reason why it has persisted.
So, it could be that homosexuality is the homozygous state of a beneficial heterozygous state.

(And, as they say on Seinfeld - "not that there's anything wrong with that")

Answer 6

The very fact that you make the assumption that evolution serves to benefit a species leaves your argument flawed. You are putting human characteristics on a natural process.

If you want proof that evolution does not work in favor of one species or another just take a look at any species that is now extinct.

Answer 7

I think homosexuality serves as population control for our species. I read in an article last year that scientists in Sweden have confirmed that homosexuality is on the genetic level so it would back up that theory.

There are also evidence that there are just too many of us on this planet and, instead of killing each other off (although, looking at current international politics, we're not far off from that), a....mutation, for lack of a PC word, had to happen to ease overpopulation.

And to answer your follow up, no, I don't think it exists because of intolerance.

Answer 8

First off, evolution does not work towards the benefit of the entire species. The reason worker bees protect the other members hive rather than themselves is because they share 100% of their genes with the queen, so working to protect the queen and her offspring is even more valuable to the worker bee than self-protection is.

Homosexuality doesn't exist to benefit the whole species. It isn't a population control. If homosexuals kept the population down by not reproducing, then their genes would never get passed on, so genes for homosexuality would cease to exist.

Some believe it exists because of kin selection - like the worker bees, homosexuals look after their relatives, who share their genes. Therefore, they protect their OWN genes, only those genes exist in OTHER PEOPLES' (relatives) bodies.

Even that doesn't make that much sense, though, because homosexuals would have to really highly increase their relatives' chances of survival, which they don't.

Another theory is overdominance - that homosexuality only happens when an individual has two genes for it. If they only have one gene for it, they carry that gene on, but are not homosexual. So perhaps having only one 'homosexual' gene is somehow advantageous for survival. Then that gene would be carried on, even though it would sometimes get paired up with another homosexual gene, causing a person to be homosexual.

The same thing happens with sickle-cell anemia in Africa. Sickle-cell anemia is a very serious disease, but you can only get it if you have two genes for it. But if you have just one gene for it, then you don't get sickle-cell anemia. AND people who have just one gene for it also are much less likely to get malaria. So the gene is preserved because it increases peoples' chances of survival, even though sometimes people end up with two of the gene and have sickle-cell anemia.

There are other similar theories for why homosexuality exists, but none of them say that it is for the good of the group. Group selection is not very popular among evolutionary biologists.

Answer 9

I think homosexuality (or even bisexuality) has been around for eons. It's more a question of whether the practice is accepted culturally. It's always been around in our culture (Western) but it's only been in the last thirty years or so (since the gay revolution of the 70's) that it's come out of the closet. While it's true that homosexuality seems to contradict the whole "survival of the fittest" passing along of the genes theory, I think that as humans we are not that simple. We are complex people, whether we are homosexual or not.

Answer 10

In an already overpopulated world, it tends to limit further overpopulation, if allowed free expression. There are other species with no males, and others with males, but the females don't need them to reproduce (sparsely distributed over large ranges, so encounters are few), but will mate if given the opportunity. The psychologists inform us that most of us are born with no particular predisposition to either heterosexuality, or homosexuality, and that it is largely cultural and religious reasons that mould all but a small percentage, which is either strongly heterosexual, or homosexually inclined. The ancient Greeks, and some modern day tribal cultures are oft quoted examples.

Answer 11

Your assumptions are false. Even the most ardent group selectionist would be embarrassed for you. You need a stringent and comprehensive review of evolutionary theory and not in social science. To answer your question. My favorite hypothesis is the sex influenced trait hypothesis. This means the same gene has different effects in different sexes. In truth, though, we do not know the evolutionary purpose of homosexuality; if even it has such purpose. Anything else is just BS.