From The Huffington Post:
For even without a causal link established between homosexuality and population management, the obvious reduction in population growth attributable to homosexuality by itself indubitably works to preserve the species. (Emphasis mine)
So "homosexuality by itself indubitably works to preserve the species", really?
Thus, my question is: Does homosexuality work to preserve the species?
Two things that are often overlooked in discussions of evolution, particularly when it comes to sexual behaviour, are sexually antagonistic traits and epigenetics. Recent studies indicate that homosexuality may be due to a normally beneficial epigenetic mechanism that occasionally malfunctions. If this is the case, then homosexuality is an abnormal consequence of a beneficial trait, and so there is no reason it should have been selected out of the gene pool.
Due to some very apt criticism regarding my comment on the question I am going to rephrase it as an answer. It is not so much that the question has an invalid premise, but that the cited article that generated the question is based on an invalid premise.
We know as a fact that homosexuals do conceive children.1 The idea that they do not is false and the idea that they did so less than heterosexuals in the Environment of Evolutionary Adaptedness is likely completely untestable. We would really need research to test this claim and none exists. The notion that this idea is in any way indubitable is just foolish. And consider this: if that is what homosexuality is supposed to be "for", then it is doing a very, very poor job considering the continued exponential growth of the human population2. Also, recent evidence is that homosexuality is not genetically determined but epigentic. This would make any sort of idea that there is a selective pressure FOR homosexuality false because it is not directly tied to genes. This means Natural Selection could not "use" it to "better" the species by making it more "stable".
If homosexuality cannot be shown to control population growth, what do we know DOES control population growth? Within other animals we know it to be things like disease (viruses, bacteria, parasites, etc), famine, and increased predation3. I see no reason to assume that humans are exempt from most of these and no evidence to conclude that we have evolved homosexuality as a method of population control, as again, current evidence shows homosexuality to be epegenetic in origin.
I imagine the author of the article thinks himself very progressive but what he is doing is actually harmful. The article seems to imply that homosexuality requires some sort of natural "utility" to make it "ok" or acceptable. This is just an extension of, or perhaps a reversal of, the Naturalistic Fallacy. It seems to be promoting the idea that if something is right or ok, it must be natural because what is natural is right, good, or ok. But if that is the only basis for why homosexuals must be treated with respect and not discriminated against then it rests on a very shaky foundation. If homosexuality is scientifically demonstrated to be a "side-effect" of a natural process, as it seems to be from recent research, then the idea that it is "natural" is eroded. If we as a society are going to make the choice that people should be respected and not discriminated against based on sexuality then we need to do so on real and not fallacious reasoning.
1 Supporting Claim that Homosexuals Conceive Children
Notice I am not claiming all homosexuals conceive children nor that homosexuals conceive children at the same rate as heterosexuals. This American Life: Double Lives
Gay man who fathered child for lesbians wins right to more access
Oscar Wilde, who is generally considered to have been a homosexual and not bisexual had two children. It strikes me as odd that people demanded a reference to this as the claim is, in my opinion, as easily verifiable as to be taken for granted since there have been so many instances of this throughout history.
2 Regarding the Exponential Growth of the World Human Population
In addition to the Wikipedia links given in the text, please see the UN's World Population Prospects site for the statistics regarding historical world population values and Human Population Growth for details regarding the mathematics for demonstrating that the world population has been growing exponentially for several centuries.
I find this question quite frustrating. It is a complete train-wreck, despite the OP's claims that it is "one of the better ones I've seen". It has received way too many upvotes from the community, despite comments pointing out some of its flaws. The answers have pussy-footed around this. It is time to go for the jugular.
The claim makes no sense whatsoever. It isn't just wrong because of its false premises and non-sequiturs. It is meaningless.
I shall use an extended analogy to try to explain this. Imagine I made the claim that:
The addition of the preservatives of sugar and formaldehyde to fruit cake have indubitably worked to preserve the recipe over the years.
You would be flabbergasted. This fruit-cake claim is riddled with errors. So is the original claim.
What does "preserve the recipe" mean? Does it mean keep the recipe unaltered? Does it mean ensuring the recipe exists in the future? Does it mean ensuring the recipe grows in popularity? Does it mean ensuring the popularity remains the same?
If it means keeping the recipe unaltered, then the act of altering it clearly doesn't preserve the recipe. Likewise, if "preserve the species" means keeping the relative distribution of genes in the gene pool the same, introducing a genetic change doesn't preserve the species. [No references. I'm arguing about (lack of) definitions here.]
Further, the fact that homosexuality appears in other related species [Example], shows that homosexuality doesn't somehow stop evolution from happening, in the same way having sugar in the recipe obviously hasn't worked to keep recipes the same, or there would only be one sugary cake. Instead, cake recipes keep changing, and fruit cake recipes keep changing - which is to say, new mutations appear, and the relative populations of the different recipes change. And species with homosexual behaviours keep evolving.
If it means ensuring the popularity/population remains the same, which is implied by "reduction in population growth", then the species is completely failing to be preserved. The population is growing, especially since the advent of homosexuality - i.e. the beginning of homo sapiens. [Ref] This weird argument defends a demonstrably false conclusion.
Fruit cakes don't contain formaldehyde. [Reference: I just made the claim it up, and I really hope it isn't true.]
Homosexuality isn't a simple matter of genetics. Reference.
Using a purely genetic argument to discuss the advent of homosexuality is flawed.
Even if fruit cakes did contain formaldehyde, it doesn't mean that it would act as a preservative in cakes. That would have to be shown empirically.
Even if homosexuality was pure genetics, it doesn't mean that there is a reduction in population growth. That would have to be shown, and is possibly wrong. [Ref: one possible counter-hypothesis: kin selection]
Even if cakes did contain formaldehyde and formaldehyde was a cake preservative, there is a huge difference between preserving an individual cake and preserving a recipe. They are at different levels of abstraction.
The claim makes a similar (common) error of confusing how evolution works - the unit of evolution is the gene, not the species. Evolution works to preserve (i.e. increase the relative population of) the successful genes, even at the expense of the species. [Reference: The Selfish Gene] The suggestion that group selection might occur through natural selection is heavily disputed.
This error in levels is further explained by evolutionary expert, Richard Dawkins, in his video addressing a similar question: "Is Homosexuality Nature’s Population Control?"
There are several false premises in the claim, showing a lack of understanding of populations and the biology of homosexuality. There is fault logic in the claim showing a lack of understanding of evolution. There is no clear definitions of the terms, making the question meaningless.
I hope I have clearly demonstrated: both the original question and my invented analogous statement are fruit-cake claims, riddled with errors.
My answer would be no, but it is not clearly proved nor provable (I don't see how it could ever be proven). I wanted to take a different angle than the other answers and I hope it will help the readers to draw their own conclusions.
If there is a correlation between population control and homosexuality, there should also be a correlation between the homosxuality rate through the ages. Sadly, we were not there to poll the population in ancient times even though it is known that homosexuality was present and accepted in ancient Greece [1] for instance. However, we do have surveys from the early 50's when the world population was only 2.5 billions compared to today 7 billions. So, looking to the research papers, can we see a correlation?
1948 [2] (World pop.: around 2.4 billions)
Had homosexual experience: 37%
More or less homosexual: 10%
Exclusively homosexual: 4%
1974 [3] (World pop.: around 4 billions)
Had homosexual experience: 27%
More or less homosexual: 7%
Exclusively homosexual: 2-3%
1977 [4] (World pop.: around 4.1 billions)
More or less homosexual: 3.1%
Exclusively homosexual: 1.3%
1989 [5] (World pop.: around 5.3 billions)
Had homosexual experience: 20.3%
More or less homosexual: 3.3%
1990 to 1995 [6-12] (World pop.: around 5.3-5.7billions)
Had homosexual experience: 9-20.8%
More or less homosexual: 2-9%
Exclusively homosexual: 1-4%
2002 [13] (World pop.: around 6.5billions)
Bisexual: 1.8% (including bisexual)
Exclusively homosexual: 2.3%
Other: 4%
2006-2008 [14] (World pop.: around 6.8billions)
Had homosexual experience: 4-6%
Exclusively homosexual: 2-4%
Considering the scientific surveys, if there is any correlation to make between homosexuality rate and population, it would be that it is decreasing as population grow. However, it is widely accepted that the decrease after early research by Alfred Kinsey is more related to wrong estimates in the first place [15]. Moreover, we can see that the rate vary a lot between different surveys reflecting inherent uncertainty of the sexual orientation.
We could also look into the census done by different countries to see if the densily populated ones show higher homosexuality rate. Warning! depending on the country, the statistics are more or less accurate.
Canada [16] - Density: 3.41/km^2 - Homosexuality rate: 1.1% - Bisexual: 0.9%
United States [17] - Density: 34.2/km^2 - LGBT rate: 3.4%
China [18] - Density: 139.6/km^2 - Homosexuality rate: 0.8-4%
United Kingdom [19] - Density: 255.6/km^2 - Homosexuality rate: 1.1% - Bisexual: 0.4%
French Republic [20] - Density: 116/km^2 - Homosexual couples: 0.6% (no data on homosexuality)
Norway [21] - Density: 255.6/km^2 - Not Hetero: 1.1% - Do not wish to answer: 5.9%
In conclusion, from the statistics, there does not seem to be any link between the popuplation number and density and the homosexuality rate. Therefore, it does seem to contradict the claim that homosexuality exist to control the population growth.
[1] Davidson, J. (2007). The Greeks and Greek love: a radical reappraisal of homosexuality in Ancient Greece. Weidenfeld & Nicolson.
[2] Kinsey, A., Pomeroy, W., and Martin, C. (1948). Sexual Behavior in the Human Male. Philadelphia: W.B. Saunders.
[3] Hunt, M. (1974). Sexual Behavior in the 1970's. New York: Dell.
[4] Pietropinto, A., and Simenauer, J. (1977). Beyond the Male Myth. New York: Times Books.
[5] Fay, R., Turner, C., Klassen, A., and Gagnon, J. (January 1989). Prevalence and patterns of same-gender sexual contact among men. Science 243, 338-348.
[6] Harry, J. (1990). A probability sample of gay males. Journal of Homosexuality 19(1), 89-104.
[7] Smith, T.W. (1991). Adult sexual behavior in 1989: Number of partners, frequency of intercourse and risk of AIDS. Family Planning Perspectives 23(3), 102-107.
[8] Janus, S., and Janus, C. (1993). The Janus Report on Sexual Behavior. New York: John Wiley & Sons.
[9] Billy, J., Tanfer, K., Grady, W., and Klepinger, D. (1993). The sexual behavior of men in the United States. Family Planning Perspectives 25(2), 52-60.
[10] Taylor, H. (1993). Number of gay men more than four times higher than the 1 percent reported in a recent survey. The Harris Poll #20. New York, NY: Louis Harris & Associates.
[11] Laumann, E., Gagnon, J.H., Michael, R.T., and Michaels, S. (1994). The Social Organization of Sexuality: Sexual Practices in the United States. Chicago: University of Chicago Press.
[12] Sell, R. L., Wells, J. A., and Wypij, D. (1995). The prevalence of homosexual behavior and attraction in the United States, the United Kingdom and France: Results of national population-based samples. Archives of Sexual Behavior 24(3), 235-248.
[13] Mosher WD, Chandra A, Jones J. Sexual behavior and selected health measures: Men and women 15–44 years of age, United States, 2002. Advance data from vital and health statistics; no 362. Hyattsville, MD: National Center for Health Statistics. 2005.
[14] Chandra A, Mosher WD, Copen C, Sionean C. (2011)Sexual behavior, sexual attraction, and sexual identity in the United States: Data from the 2006–2008 National Survey of Family Growth. National health statistics reports; no 36. Hyattsville, MD: National Center for Health Statistics.
[15] McWhirter, D., Sanders, S., and Reinisch, J. (Eds.). (1990). Homosexuality/Heterosexuality. The Kinsey Institute Series. New York: Oxford University Press.
[16] http://www42.statcan.gc.ca/smr08/2011/smr08_158_2011-eng.htm
[17] Gates, Gary J.; Newport, Frank (October 18, 2012). "Special Report: 3.4% of U.S. Adults Identify as LGBT".
[18] http://www.chinadaily.com.cn/english/doc/2004-12/02/content_396559.htm
[20] http://www.insee.fr/fr/themes/document.asp?ref_id=ip1435
[21] http://www.ssb.no/a/english/publikasjoner/pdf/rapp_201038_en/rapp_201038_en.pdf
indubitableclaim in the question.