The Evolutionary Purpose of Male Homosexuality

A recent show on the science channel alerted me to an interesting new hypothesis about the evolution of homosexuality. Contrary to popular thought, it does not appear to be an accident. (If anyone can find documentation about this new hypothesis... let me know). Particularly interesting is the behavior of primate males in family groups. As is well known, apes (such as chimanzees, bonobos, and gorillas) that live in family groups consist of many females, one dominant male that gets exclusive access to mating with the females, and sometimes one or more submissive males that do not have the right to mate with the females. A new scientific hypothesis suggests that our early ancestors (who may have lived in similar family groups) may have developed homosexuality among these "submissive" males. The sexual behavior of the apes currently being studied suggests that male homosexuality has an important evolutionary advantage in family groups. The submissive males engage in homosexual behavior as a way to satisfy sexual instincts... but the advantage goes further than that. By engaging in homosexuality, the submissive males present themselves as no threat to the dominate male and thus promote group harmony, by discouraging male fighting over mates. Furthermore, these homosexual males provided survival advantages to the family group by helping to protect the females and infants from predators and rival family groups and to find food for the group. In this case, the sacrifice of the genetic survival of one individual gave an enormous advantage to the survival of the group. - Which is something evolution has been known to favor.

Although this particular advantage of homosexuality is obsolete for humans, the homosexual orientation would have survived despite that because our society changes far faster than evolution.

So.. for any homophobes that claim homosexuality is "unnatural" - Au Contraire! It is VERY natural, for some people!

Views: 4123

Tags: Science, biology, evolution, gay rights, homophobia, religion

Comment by Marissa Karp on March 8, 2012 at 8:57pm

I haven't studied population trends or homosexuality in any depth, really, but I was toying with the idea that rates of homosexuality might rise in times when, globally, food is running low...

Comment by Unseen on March 8, 2012 at 9:40pm

You're a hoot.

Comment by Rob Klaers on March 8, 2012 at 10:59pm

@Unseen.. Perhaps the part that environment plays is the degree to which homosexuality is ignored or scorned in the particular environment.

I believe you're confusing society's views with environment. The two are different. The way I see environment playing a role is in regards to population. Such as once a certain population concentration is has been attained it flips a switch (if you will). Since it's a biological trigger it would continue to keep it a genetic factor. There are a number of instances where an individual of a species (a several species of fish for example) change from one sex to another to compensate for a lack of particular sex. Since humans can't physically change sex naturally, some other change would need to happen. This could be a chemical or maybe a hormonal change. .. Of course this is just conjecture on my end.

Comment by SteveInCO on March 9, 2012 at 1:08am

I guess going off and doing gay sex because you cannot get laid by female apes in a polygamous culture is preferable to the "modern" alternative of flying planes into buildings.

Comment by Ward Cressin on March 9, 2012 at 1:13am

Shabaka Tecumseh, please then explain the gays and lesbians who don't live the gay/lesbian lifestyle. I know more than one gay man who does not live the gay lifestyle but is exclusively attracted to guys. Because of who I associate with I can only point out science fiction/fantasy fans who are gay but I'm sure others here know people who are gays or lesbians that you wouldn't know it from the way they dress or talk or their apartment/home.

Rob Klaers, "The way I see environment playing a role is in regards to population. Such as once a certain population concentration is has been attained it flips a switch (if you will). ..."

There has been some potential verification of this idea but only on a local scale: birth order, and maternal relative's fecundity (are two that I know of). If it were valid on a larger scale, large old cities should have a greater percentage of gays/lesbians than can be accounted for by the movement of rural gays/lesbians to cities. Tokyo, Delhi, Calcutta, London, New York just to list a few should have increasing percentages in spite of social pressures if this was correct on a large scale. It would be an advantageous adaptation and might become one (assuming we survive).

There is sufficient evidence that there is a genetic component (in spite of what people like Shabaka believe). But given the local scale expression, I doubt expression of homosexuality in an individual is purely genetic – there seems to be an epigenetic portion of the equation. Are there also sociological components? That's an even bigger and more difficult to answer question.

Comment by Shabaka Tecumseh on March 9, 2012 at 5:40am

Ward people who say they are homosexual, but don't practice same sex either practice abstinence or become asexual. Most humans admire people of the same sex for whatever reason, that's not "abnormal." Look I don't know for sure to what degree homosexuality is genetic, but I can say it's aberrant in Nature. I don't know because of today's ability to alter genes that could drop the testosterone levels in men and increase them in women.  I don't know because having such large male prison populations without females can alter the males lifestyle perspectives. I don't know if there a effort afoot to use homosexuality as a population control tool.  I just don't know those things, but I can say with certainty that it is aberrant in Nature. 

Comment by Pope Beanie on March 9, 2012 at 2:19pm

I think that the kind of same-sex sexual behavior documented in prisons and in overcrowded rat populations is a separate subject from the subject of how sexual preference comes to be in uncrowded populations. Even if there is a nature-induced correlation between over-crowded conditions and less baby making, homosexuality still occurs to a significant extent in uncrowded conditions.

Comment by Rob Klaers on March 9, 2012 at 9:27pm

@Ward ... I see your point. On the other hand, it hasn't been unknown for otherwise straight men to have 'wives' who in prison. Now, that could be argued that it's for general companionship not otherwise available in prison. Though, like my hypothesis does, it plays off what Arch said earlier in relation to over-population. I don't think that's the sole reason by far.. just one of many possibilities which could play off each other. ... For some reason this makes me think of binary coding. Some trigger that flips a genetic switch on (1) or off (0). With the majority of genetic switches determining the final outcome.. Again, just conjecture on my end,

Comment by Ward Cressin on March 11, 2012 at 12:17am

@Shabaka Tecumseh: "... I can say with certainty that it is aberrant in Nature."

Not if you are trying to tell the truth. If you don't have all the facts which you obviously don't then you should listen to those who know more. For example, you might want to read this thread but not comment except to ask genuine questions.

@Rob Klaers - the str8 men in prison having sex has puzzled me - it would be interesting to find out more about the break-down of who does and doesn't engage in prison sex: are there some men who will never (willingly) enage in prison sex? the physiological characteristics recognized in gay men - do only those who engage in prison sex have those physiological characteristics (even if str8 outside of prison)? Does the crowed-rat syndrome provide sufficient explanation for prison sex? And so on.

While homosexuality and evolution are the main ones, there are many questions that aren't being answered because closed-minded theists are figthing against science. And with homosexuality, I worry that when a genetic component is found, theists will choose to terminate gay/lesbian fetuses (in spite of their supposed anti-abortion stance) causing a decline in human civilization.

I have not done a scientific study but in my informal analysis of influential / creative people I have found a high correlation with the physiological characteristics recognized in gays/lesbians. Very few complex traits (like homosexuality) are linked to only one gene. But one gene can link to several traits. While we might joke about theists being sheeple, I think trying to eliminate any gay/lesbian gene(s) would turn humans into actual sheeple (unimaginative drones).

Comment by Rob Klaers on March 11, 2012 at 4:47am

@Ward
I don't think it would be a question of aborting fetuses, for the theists it would be just a question of attempting to convert them when they were young. I'm sure after awhile there would be a number of 'How to make sure from birth your child isn't gay" programs/books/videos.. Of course you'd have those who'd refuse to believe it even if there was a genetic factor, so you might have more babies given-up for adoption.  Not that there aren't already too many in the system now.  

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