Study reveals potential evolutionary role for same-sex attraction

Male homosexuality doesn't make complete sense from an evolutionary point of view. It appears that the trait is heritable, but because homosexual men are much less likely to produce offspring than heterosexual men, shouldn't the genes for this trait have been extinguished long ago? What value could this sexual orientation have, that it has persisted for eons even without any discernible reproductive advantage?

One possible explanation is what evolutionary psychologists call the "kin selection hypothesis." What that means is that may convey an indirect benefit by enhancing the survival prospects of close relatives. Specifically, the theory holds that homosexual men might enhance their own genetic prospects by being "helpers in the nest." By acting altruistically toward nieces and nephews, would perpetuate the family genes, including some of their own.

Two evolutionary psychologists, Paul Vasey and Doug VanderLaan of the University of Lethbridge, Canada tested this idea for the past several years on the Pacific island of Samoa. They chose Samoa because males who prefer men as sexual partners are widely recognized and accepted there as a distinct gender category—called fa'afafine—neither man nor woman. The fa'afafine tend to be effeminate, and exclusively attracted to adult men as sexual partners. This clear demarcation makes it easier to identify a sample for study.

Past research has shown that the fa'afafine are much more altruistically inclined toward their nieces and nephews than either Samoan women or heterosexual men. They are willing to babysit a lot, tutor their nieces and nephews in art and music, and help out financially—paying for medical care and education and so forth. In a new study, the scientists set out to unravel the psychology of the fa'afafine, to see if their is targeted specifically at kin rather than kids in general.

They recruited a large sample of fa'afafine, and comparable samples of women and heterosexual men. They gave them all a series of questionnaires, measuring their willingness to help their nieces and nephews in various ways—caretaking, gifts, teaching—and also their willingness to do these things for other, unrelated kids. The findings, reported on-line this week in the journal Psychological Science, lend strong support to the kin selection idea. Compared to Samoan women and , the fa'afafine showed a much weaker link between their avuncular - or uncle like - behavior and their altruism toward kids generally. This cognitive dissociation, the scientists argue, allows the fa'afafine to allocate their resources more efficiently and precisely to their kin—and thus enhance their own evolutionary prospects.

To compensate for being childless, each fa'afafine would have to somehow support the survival of two additional nieces or nephews who would otherwise not have existed. "If kin selection is the sole mechanism by which genes for male same-sex sexual attraction are maintained over time," the fa'afafine must be "super uncles" to earn their evolutionary keep, explains Vasey. Consequently, Vasey suggests "that the fa'afafine's avuncularity probably contributes to the evolutionary survival of genes for male same-sex sexual attraction, but is unlikely to entirely offset the costs of not reproducing."

Do these findings have any meaning outside of Samoa? Yes and no. Samoan culture is very different from most Western cultures. Samoan culture is very localized, and centered on tight-knit extended families, whereas Western societies tend to be highly individualistic and homophobic. Families are also much more geographically dispersed in Western cultures, diminishing the role that bachelor uncles can play in the extended family, even if they choose to. But in this sense, the researchers say, Samoa's communitarian culture may be more—not less—representative of the environment in which male same-sex sexuality evolved eons ago. In that sense, it's not the bachelor uncle who is poorly adapted to the world, but rather the modern Western world that has evolved into an unwelcoming place.

Citation: Study reveals potential evolutionary role for same-sex attraction (2010, February 4) retrieved 22 April 2019 from https://medicalxpress.com/news/2010-02-reveals-potential-evolutionary-role-same-sex.html
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Feb 04, 2010
This doesn't explain anything about how homosexuality continues to perpetuate given the fact that homosexuals are much less likely to reproduce

Feb 04, 2010
This only explains how the eventual gene or something else might have value in nature; not what it's composed of. How come it suvives, in it self?

Feb 04, 2010
Actually, homosexuality is an artifact of all bird and mammal life, including humans, and has continued through the ages quite irrespective of any kinship behaviors, laws, persecution, discrimination, etc. One can only conclude from this data that homosexuality is intrinsic to all animal life, INCLUDING humans. Sex is good. Bonding is fostered by sex, all sex. Period. Full stop. It doesn't need to be explained. It just is. What needs to be explained scientifically is why anyone in their right mind continues to take exception to this rather unavoidable fact, or study it.

Feb 04, 2010
Increasing the odds of your nieces and nephews survival preserves part of the homosexual's genetic heritage because each of them has half of their uncle's genes. If there is one gene pair that is critical the homosexuality, each niece and nephew has half of the pair.

Feb 04, 2010
This kind of seems like grasping at straws to me. Completely removing morality from the debate, homosexuality does seem at this point to have a genetic component, but it obviously has a cultural component as well, and it seems very unlikely that every homosexual harbors this preference because of their genes. A more likely explanation is that it is simply a random mutation that pops up in a certain percentage of most species. There is a big difference between a mutation and an adaptation. And there just isn't really any way to spin homosexuality as providing some kind of reproductive advantage for the individual.

Feb 04, 2010
The limitation to this and similar studies is that they view homosexuality as a trait on its own, rather than as simply one of the more obvious of a genetic "grab bag" of traits. Homosexuals are born the way they are, there is no morality or choice invloved. However, homosexuals display a greater tendency towards left handedness, creativity, cleverness, schizophrenia and emotional problems.

These traits in a primitive setting where evolution has sway, alongside their ability to act as "super uncles" would create a slight advantage genetically to their relatives.

Intuitively, if the number of homosexuals in a given human population were too large, it would likely be unstable. The reason that homosexuality is common in certain animals is that it confers this small social advantage. In nature, even raising a survival/reproductive advantage 5% would mean a huge advantage longterm (generationally).

Homosexuality is only advantageous to social animals

Feb 04, 2010
This article doesn't mention the role of homosexual men during a time of a crisis. These men would play a very positive role during conflict since they would be less likely to be in a "warrior" cast. I think the role of homosexuals being protectors and providers when fathers and brothers are off fighting is a very advantageous trait.

Feb 04, 2010
This article doesn't mention the role of homosexual men during a time of a crisis. These men would play a very positive role during conflict since they would be less likely to be in a "warrior" cast. I think the role of homosexuals being protectors and providers when fathers and brothers are off fighting is a very advantageous trait.


Then why is the armed forces full of homosexuals?

Feb 04, 2010
BookBinder : Bonding is fostered by sex, all sex. Period. Full stop. It doesn't need to be explained. It just is. What needs to be explained scientifically is why anyone in their right mind continues to take exception to this rather unavoidable fact, or study it.


Your thinking would take us back to the Inquisition! Yeah, the sun DOES rise every morning ... so why bother studying it!..
You are anti-science, or, at best, merely misunderstand its nature (pun intended!)

Feb 05, 2010
Wow i came to the conclusion about it dying out years ago. My theory involves homosexuality being a product of epigenetics. An increase in homosexuality in modern times could be due to exposure to chemicals such as BPA, the synthetic estrogen hormone found in plastics, which have become much more prevalent.

Feb 05, 2010
The scientific problem is not homosexuality but exclusive homosexual desire.

It also concerns phenotypic displayed homosexuality in modern societies that might not have been so openly expressed in nonWestern ones.

Most male homosexuals in Western societies would not adopt fa'afafine like roles in any society. Instead, they would as most did before gay liberation have married and have had children [even exclusive homosexuals will engage in heterosexual if they lack choice]. Lacking heterosexual inclination they would have have lacked extramarital offspring. In some circumstances that might have lead them to devote more resources to their offspring and avoided the costs of intermale conflicts that occur with chasing after other men's women. That would be enough to select for such genes that now are openly expressed in exclusive homosexuality.

VOR
Feb 05, 2010
"homosexual men are much less likely to produce offspring than heterosexual men" and "homosexuals are much less likely to reproduce"....
Implies a remaining chance (lol). Of course maybe they mean homosexuals reproducing hererosexually, but those people are bisexuals. Bisexuality seems to always get lumped into homosexuality, but it seems there are plenty of strict homosexuals, so its incorrect to lump them together.

Feb 05, 2010
Do Samoans have any problems with their homosexual uncles lusting after their young nephews?


Typically when you accept someone openly for who they are, the incidence of deviance within the population drops.

Happier people perform fewer socially unacceptable acts. Oppressed people become depraved. Perhaps you should include that in your viewpoint. Rabid homophobism causes deviance, not the other way around. Be a little more open minded. You don't have to like it, but you have to get over it.

Feb 05, 2010
What the article seems to be saying is that a homosexual man can ensure that his genes are continued by ensuring the survival of two newphews or nieces who would othwerwise have died.

This makes soem sense arithmetically (since if a brother or sister shares half his genes, two of that persons chidren likely carry that half (1/4 each) into succeeding generations - whic his genetically the same as the homosexual man producing one child himself (1/2 his own genes into the next generation)

Two seems a little high, though we are talking about pre-industrial society.

taking the last paragraph of the article at face value - does the loss of directy (i.e. life saving) kin influence of homosexual men in an increasingly separated society mean they are in danger of breeding themselves out of the gene pool?

P.S. The people above making veiled moral commentary on this scientific debate need to get a life.

Feb 05, 2010
"Of course maybe they mean homosexuals reproducing hererosexually, but those people are bisexuals.


Not neccessarily, cultural or social constraints also determine who produces offspring, especially in more ancient societies. I expect in history, many more gay men fathered children heterosexually without being bisexual.

Feb 05, 2010
This research team is confusing homosexuals with transgender people. Only a small percentage of homosexual men can be described as feminine (I dislike the term effeminate because it is unnecessarily derogatory) and engage in stereotypically female behaviors. If given access to hormone replacement therapy and modern surgical techniques, I wonder how many fa'afafine would transition to female? Although a male to female transgender person is still transgender whether or not they've under gone any kind of medical treatment. Surgery doesn't 'make' anyone male or female if they didn't already identify as so to begin with. A woman with a penis who identifies as a woman is just that, she's not a man.

This article even explicitly states that the fa'afafine are a THIRD gender, that's not the same as being homosexual! Seems to me that Vasey and company need to go through a little trans-inclusive LGBT 101 before continuing to receive funding for these projects.

Feb 05, 2010
More info on the topic:
http://www.amazon...88160044
The 'public' front end of a broad research project on human sexuality.

Baker puts an interesting statistic in the bucked: When all 'homosexual' persons, both bisexual and strictly homosexual' are placed together in a group. The birth rate of this group is higher and the age of first child birth is a couple of years earlier. These data holds for all the western world.

Taken in this light the proliferation of the homosexual genes (there are probably multiple) is an easy one, they have more children as a group.

A second observation was that the age of first sexual intercourse (both home and hetero sexual) was on average 3 years earlier for this group. Most homosexual contacts were in younger years. This explains the success of this sexual strategy: learn young, get better at it than your age peers and get more children later on.
These are group statistics, individuals are unique

Feb 05, 2010
Frajo, while I agree with the sentiment of slapping the idiot marjon for his/her moronic drivel, I wouldn't give them the column inches by replying.

Feb 05, 2010
I do think we should support our Marlon Brando look-alikes. He was a good actor. Locker rooms are irrelevant, heterosexuals are far more likely to do bad things to the gay guy in there than the other way around. There are heterosexual men who are girl scout leaders and have been and probably still are homosexual men who were boy scout leaders and fewer of them abuse their charges than their heterosexual counterparts have done.

Feb 05, 2010
We should embrace NAMBLA's philosophy?

You keep reverting to your inept comparison of abuse and molestation being akin to a consenting adult action.

Perhaps you are the one who cannot discern right from wrong.

Since you're such an advocate of adult interaction being akin to molestation, should we repeal the laws concerning the age of consent in your world as long as those engaged are of opposite sex?

Feb 05, 2010
We're not talking some cultures, we're talking YOUR culture. Answer the question please.

Feb 05, 2010
I was just asking if the uncle persuades nephews he is attracted to or is that taboo?


Is it taboo when an uncle persuades nieces he is attracted to? Just asking...

Feb 05, 2010
Sex is an extravagent waste of energy for anything other than propagation, in all animals including us.


Not so. Take a look at the bonobos:

http://en.wikiped...behavior

Feb 05, 2010
NAMBLA considers man-boy love to be natural. Why are they wrong?
Modern western culture promotes sexual activity among all ages as long as it is consensual and not forced.

You answered your own question. When it comes to man-boy "love", it's very difficult to conceive of a scenario where it's both consensual and not forced. Adults have a great coercive and authoritative sway over children. Moreover, most (perhaps all) children don't find adults to be particularly attractive or erotically arousing... Lastly, a child can't be expected to make responsible decisions, particularly ones that can affect his/her long-term physical and mental health. Therefore, in light of all these considerations, any adult-child sex is automatically suspect and is, far more likely than not, abusive.

But I fail to see the relevance of pedophilia, when the topic at hand is "evolutionary role for same-sex attraction". The two are about as compatible as a dog and a cat.

Feb 05, 2010
Chimps are very warlike- bonobos may be using alternative sex to reduce conflict over resources caused by population pressure.

No population pressure required. It is a simple calculation: fights are a lot more expensive than sex. It is much easier, less stressful, not to mention more enjoyable, to resolve conflicts and maintain group cohesion through sex instead of aggression.

Feb 05, 2010
Only if that sex does not result in unwanted pop growth and the resulting struggle over finite resources.

Supposedly, bonobo fertility is down-regulated to compensate for the more frequent sex. On average, bonobo females give birth about as frequently as chimp females. So it all works out.

Which only goes to show: there's more than one way to skin a cat, screw the pooch, or pick your favorite metaphor... =)

Feb 05, 2010
The vast majority of pedophiles, while male, are also heterosexual (i.e. man-girl, not man-boy, dominates the agenda), so this whole tangent is pointless and OT.

But if you really wish to explore the boundary of "childhood", you could start with puberty (the Biblical method.) Or you could define it as boys growing facial hair (and roughly same age for girls.) Or you could get a bit more modern, and look at maturation of the brain, which only begins to level off in the early 20's.

Feb 06, 2010
marjon,

Looking at your views and the opinions that drive them one must question your history if you cannot understand coersion vs consent.

Feb 06, 2010

Is it possible all species have some built-in protection against over-population in which certain specimens in the herd would not desire offspring?
How would you know if people are on-topic or not if you dont read previous posts? This notion has already been outed.

What does this mean, that the idea that members of some species have mechanisms that limit the success of reproductive behavior is false? Because it seems certain that they do. After all, some species possess the reproductive capacity to produce millions of offspring per act of mating, while others may mate multiple times before the successful conception of even a single offspring. Some species even routinely produce infertile members at a regular rate in certain environmental conditions. And the energy-intensiveness of mating varies by species too. Some species spend their entire lifetime's worth of energy to mate, while in humans, the act of mating can be no more intensive than a brisk jog

Feb 06, 2010
Is it possible all species have some built-in protection against over-population in which certain specimens in the herd would not desire offspring?


When you remove environmental reinforcers those safeguards fail.

That being said, the human safeguard is war as disease eradication has become relatively easy for us.

Feb 06, 2010
Wow, so, someone picks a random social custom, practiced on a remote island by an infinitesimal percentage of the species and then draws "conclusions" about the role of homosexuality in evolution?

Amazing thing this is, the "science" of psychology. Where are your degrees from, the Hogwash School of Advanced Magic?

Roj
Feb 06, 2010
The article ignores that some genetic mutations are always represented as 1% of the population. Specific birth defects, diseases, or extraordinary deviations, including homosexuality, are frequently counted as 1% of the population.

There may be enough unique mutations existing at 1% each, for 100% of the population to be some kind of mutant 100% of the time.

Feb 07, 2010
I think it's absurd that every trait needs some explanation -- somethings just come as a byproduct of a very complex system. Sex is needed for survival, the organism's brain is primed for it, a few parameters go off a bit and you have attraction to the same sex. It's probably something that cannot be "optimized" out by evolution due to other competing factors (hormone levels, degrees of desire etc).

Feb 07, 2010
So I am not a scientist, etc, and is the reason that the inheritability of female homosexuality is not studied, is that it is recognized that human females rarely had the option of not reproducing?

And given that most females were not allowed to remain single by choice, couldn't the homo gene be passed on through women?

But regardless of that, it makes no sense to assume that EVERY mutation survives because that mutation has a positive quality. It seems like some mutations should survive if they have only a neutral quality and did not directly create a negative.

Feb 07, 2010
This comment has been removed by a moderator.

Feb 07, 2010
Lol, yes I was kinda forgetting to mention that "the gay gene" isn't validated. Some studies have indicated that gayness may be encouraged by fetal exposure to certain hormones but I don't think anyone really knows for sure what causes it.

Feb 07, 2010
Homosexuality is most likely a mis-wiring of the brain and its associated actions towards sexual behavior. In the world of the construction electrician common mis-wirings occur over and over again with the same results. These mis-wirings are well known and great effort is taken to eradicate them but they still occur. They still occur because the process of screwing it up begins anew with each job as the passing of instructions is not perfect and each job is different in some way so the eradication process must also begin anew. It's easy to rewire a building if you get it wrong, not so for a brain.

Feb 07, 2010
Perhaps this is more psychological than we think, maybe your sexual orientation is created in the very first 1-2 years of life by family members. Perhaps it is a(n) hormonal balance issue during pregnancy or puberty, or even the "sex gene".

I'm going to ask a question. What if there were a society that embraced sexual freedom among both sexes? What if society portrayed all men and women to be bisexual, and everyone you knew was, would this conjure more bisexual persons in that society? If so does that say that the "majority" of people are able to be shaped and influenced, and then there are some (maybe close to half) that are more set, so to speak, on one sex?

There have been stories of older women residing over to women (due to the higher death rate among older men, leaving older women alone), so if one group is that flexible, couldn't the rest of us be? I'm not saying sexuality is ONLY formed by society, close people (such as family members), I'm just asking a few questions.

Feb 08, 2010
Economics and growth of cultures and their downfall has not been discussed. Our civilization lies in the wake of these changes. I care about us as a country and the predictable examples of past history. In many cultures the rise of deviant norms and the debates of those norms are declared normal and even praised as better. It also happens to mark the peak of a civilization. From that point on it is a decline. Growth of population, comes from solid norms, common identity and strong families. They are the cornerstone of growing strong civilizations. I am sorry to say that deviant forms of behavior and identity are not atrributes of civilization. It is a return to animalistic chaotic barbarian attributes. No exceptions in history. There is nothing new under the sun except for new tech. Our societies function exactly as they did for thousands of years. Technology has only accelerated the process like a catalyst. Explaining these behaviors is not rocket science

Feb 08, 2010
Do Samoans have any problems with their homosexual uncles lusting after their young nephews?


No more than heterosexual uncles lusting after their young nieces.

Feb 08, 2010
I am sorry to say that deviant forms of behavior and identity are not attributes of civilization.


And who the hell are you to decide what is deviant and what is not?

Feb 08, 2010
I am sorry to say that deviant forms of behavior and identity are not attributes of civilization.

And who the hell are you to decide what is deviant and what is not?

Excellent point. When considering the broad global anthropological context, both in space and in time, it is rather the Judaic religions' virulent homophobia that is clearly deviant. And not just the homophobia, but the general sex-o-phobia, evident in draconian norms of "modesty" and "propriety". The Puritanical cultural norms in this regard, still hanging about America neck to this day, are surpassed only by the brutal tyranny of the modern Islamic states.

Feb 09, 2010
1) The prevalence of homosexuality is too high to be considered a "random mutation" that pops up in populations. If it is a genetically constrained phenotype then it must be either adaptive or a byproduct of other adaptations.

2) Some people are missing the way in which kin selection works. Kin selection means that I don't have to pass on my genes directly. I can get the same benefit of direct reproduction by ensuring that a certain number (depending on genetic relatedness) of my relatives live to a reproductive age and pass on their genes.

3) There is other evidence that supports this idea. For example, homosexuality seems to be matrilineally biased (on the mothers side). This makes perfect evolutionary sense as only females know 100% if a child they produce is theirs. A male's paternity is always in question. As such, a mothers brother giving-up his own reproduction to aid his nieces and nephews (who he knows he is related to) supports the kin-selection theory.

Feb 10, 2010
I am sorry to say that deviant forms of behavior and identity are not attributes of civilization.
That isn't what was said. Deviance is a result of the society which is a result of the state of the civilization. And, yes, yes it is. It's called the progression of decadence hypothesis.

And who the hell are you to decide what is deviant and what is not?

Deviance isn't necessarily a bad thing. Allowing blacks to attend University with whites was deviant in the 50's. It's a deviation from the societal norm. Try to ignore the improper connotation that the word implies.

Feb 10, 2010
The Puritanical cultural norms in this regard, still hanging about America neck to this day, are surpassed only by the brutal tyranny of the modern Islamic states.


Uganda and the upcoming slaughter of homosexuals isn't too far off from the same type of brutal tyranny that Islam represents to so many, while those same traits are conveniently ignored in Judaic traditions, probably for social acceptance reasons.

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