The Evolution of Gay

  • Posted by a hidden member.
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    May 06, 2013 7:09 PM GMT
    As an ecologist, I'd like to talk about gay evolution and ecology!

    I find homosexuality interesting from an evolutionary perspective. Traits tend to evolve to increase reproductive fitness, if not of the individual then of those of close genetic relation. Obviously homosexuality has distinct disadvantages regarding reproductive fitness, so why hasn't it been stomped out of our evolutionary heritage? There are a couple theories I've come across:

    1) Homosexuality is a mechanism to combat overpopulation.
    2) Homosexuality increases the reproductive fitness of family units by adding extra resource acquisition capacity without increasing within-group male reproductive competition.

    I find #1 to be dubious as there would need to be an overpopulation trigger mechanism that could be observed to correlate with an increased percentage of homosexuals. It would follow that countries with starving populations or those with high population densities would have more gays, but I don't think this has yet been observed in poor African or dense Asian countries. You might make the case that big cities have increased gay density, but that is likely due to other factors. There could be other triggers, but none that I know of have been observed.

    #2 is far more likely, although for most animals it is only females that forego reproduction to assist in resource gathering or rearing of offspring. I think there are a lot of possibilities here.

    On a related note, the males of some species of cuttlefish (and I think some other animals) who are smaller and/or less aggressive actually disguise themselves as females to sneak past the guarding dominant male and secretly impregnate the females. Maybe metrosexuals are trying out this strategy...

    Thoughts on these? Any other theories you've thought of or come across?
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    May 06, 2013 10:01 PM GMT
    One study I came across did a study of biological twins where one twin was gay and the other twin was straight. What they found was that the straight twin was often much more promiscuous than average, leading the researchers to believe that the gene(s) that may cause homosexuality in some people might manifest themselves as a higher sex drive in others, which allow for that person to have a lot more children. This would ensure that homosexuality would get passed on as a trait throughout the generations.


    I don't have a link to the study, but if I find it I'll post it.
  • Lincsbear

    Posts: 2605

    May 06, 2013 10:21 PM GMT
    No.2 sounds plausible.
  • calibro

    Posts: 8888

    May 07, 2013 2:10 AM GMT
    it has to do with butterflies... no one ever suspects the butterfly
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    May 07, 2013 2:26 AM GMT
    I like this thread.
    I've always kind of suspectef theory #2
  • pharmstudent

    Posts: 162

    May 07, 2013 2:39 AM GMT
    One thing is for sure the gay trait is favored by nature, otherwise it would've been long extinct. Nature wants to see more gay dudes getting at it. I personally like the "your mom is a slut" theory where the man loving gene is so potent it transfers to the child.
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    May 07, 2013 2:53 AM GMT
    It seems you think in term of male gayness, and forgot homosexuallity exist in female too, which would invalidate your invalidation in 2 ;-)

    Yet, 2 is unlikely, as there is a huge range of 'taking care of offspring' strategies, ranging for doing nothing at all up to group raising.

    Yet homosexuality is observed in all animal kingdom, from insects to mammals. So it sound unrelated to any offspring raising strategy.

    I strongly believe it's just a side effect of a strongly positively selected mechanism of partner selection favoring variability in mate selection.

    Obviously, a animal should bread within it's own species to get a good reproductive fitness, so the mate need to be 'close', ie, no frog dating a bird.

    Yet, genetic diversity improve population ability to adapt to changing condition, and many study demonstrated an tendancy in animal kingdom to avoid mate genetically to close : no breeding between sister/brothers, male of female living territory to find mates etc...

    It's possible that those two contradicting evolutionary goals favor variability in the sexual attraction process.

    So if the system in the brain making a animal 'identify' a sexually attractive mate is tuned up to provide a wide range of attraction, we are just the bug making us identify same gender people as sexually attractive.

    It's just like some keeping a stock of poor or dangerous genes just because, in some condition, they become favorable.

    Evolution doesn't produce perfect organism, it just keep changing them.



  • tobyb

    Posts: 111

    May 07, 2013 3:10 AM GMT
    Interesting thread.

    I like no. 2 over no. 1. But I think it's less to do with adding "gathering capacity" as you put it, and more to do with smooth and productive functioning of society.

    I'm no sociologist or biologist, but I do think that gay people's presence and acceptance in society has for eons been associated with the most affulent and successful societies. I think that's because the presence of gays - do see things and do differently - not just what's sexy, but all sorts of ways they behave - forces others to examine whether what they're doing is the right or best way to do something. The presence of a diversity of opinion drives progress, as then the best solution or the best idea will survive and thrive. Without gays, human society would be more likely to function like that of ants or termites: do what is expected, no variation.

    The benefits of accepting difference is taught to kids all the time - how many kids books and movies teach kids "don't listen to everyone else, do what you think is right, and if you are, they will come around." Human progress depends on that point of view being allowed to exist. No wonder that the most successful human societies have always accepted gays, and the most repressive ones are usually economically backward too.

    So, I think gayness is not just helpful to human evolution; I think it's essential. :We know most straight people are capable of a bit of gay sexuality: that's shown by sex life in prisons and on long sea journeys and in all womens college dorms. So color me a little "Gay supremacist," I suppose. I think bisexuality/gay variations are not just tolerated in human evolution, I think they're vital to it.
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    May 07, 2013 3:17 AM GMT
    Toby, I don't think homosexuality in a human paradox, it's just an animal kingdom paradox.

    Any explanation for it related to human social structure fall on it's face when looking at animal homosexuality.
  • tobyb

    Posts: 111

    May 07, 2013 3:23 AM GMT
    Maybe. I'm no biologist or geneticist, I'm just sharing my amateur observations and ideas. But I think we don't know much about animal sociology yet, let alone what effect animal homosexual behavior has on animal societies.
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    May 07, 2013 3:48 AM GMT
    minox saidIt seems you think in term of male gayness, and forgot homosexuallity exist in female too, which would invalidate your invalidation in 2 ;-)

    Yet, 2 is unlikely, as there is a huge range of 'taking care of offspring' strategies, ranging for doing nothing at all up to group raising.

    Yet homosexuality is observed in all animal kingdom, from insects to mammals. So it sound unrelated to any offspring raising strategy.

    I strongly believe it's just a side effect of a strongly positively selected mechanism of partner selection favoring variability in mate selection.

    Obviously, a animal should bread within it's own species to get a good reproductive fitness, so the mate need to be 'close', ie, no frog dating a bird.

    Yet, genetic diversity improve population ability to adapt to changing condition, and many study demonstrated an tendancy in animal kingdom to avoid mate genetically to close : no breeding between sister/brothers, male of female living territory to find mates etc...

    It's possible that those two contradicting evolutionary goals favor variability in the sexual attraction process.

    So if the system in the brain making a animal 'identify' a sexually attractive mate is tuned up to provide a wide range of attraction, we are just the bug making us identify same gender people as sexually attractive.

    It's just like some keeping a stock of poor or dangerous genes just because, in some condition, they become favorable.

    Evolution doesn't produce perfect organism, it just keep changing them.





    Good point, I was thinking primarily of the males, but females foregoing reproduction in social animals is fairly common where as for males it is not.

    Evolution definitely doesn't produce perfect organisms, but mutations that seriously affect fecundity are usually quickly reduced to only rare expression. I wouldn't call homosexuality rare.

    As for homosexuality in the animal kingdom, I will admit a lack of research on my part, but from what I understand homosexual encounters are usually ephemeral, with individuals still engaging in heterosexual breeding which would pass on genes. For humans this would be the case if for most of our history homosexuals still tended to have heterosexual encounters producing offspring. If this is the reason for the continuation of gay genetics, then a more accepting social atmosphere where gays feel less pressure to engage in heterosexual sex and adoption is more common than surrogacy there should be a reduction in the rate of expression of genetic homosexuality.

    This would all be irrelevant if, say, the gene responsible for homosexuality is actually widely expressed but is only activated in a small portion of carriers by environmental cues either in the womb or from social experience.
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    May 07, 2013 4:04 AM GMT
    I would say #2. Love your thinking!
  • Arcangel7769

    Posts: 106

    May 07, 2013 4:51 AM GMT
    calibro saidit has to do with butterflies... no one ever suspects the butterfly


    You mean that butterfly that keeps flapping its' wings and causes a hurricane on the other side of the world? Sheesh! Someone should just swat it. Poof! No more hurricanes! icon_lol.gificon_lol.gificon_lol.gif
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    May 07, 2013 5:05 AM GMT
    Are those the only two possibilities? Perhaps homosexuality is just a common mutation, and there is no more meaning behind it than that. And, as gay mutants, perhaps our special power is brotherly love.
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    May 07, 2013 5:31 AM GMT
    #2 sounds fairly dumb.
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    May 07, 2013 6:21 AM GMT
    Not trying to be a jerk here, but don't forget Humans are a species of Primate. Primates are Mammals and Mammals are part of the Animal Kingdom.

    I just feel like people forget that Humans are animals too.
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    May 07, 2013 6:59 AM GMT
    CaCO3 said

    Evolution definitely doesn't produce perfect organisms, but mutations that seriously affect fecundity are usually quickly reduced to only rare expression. I wouldn't call homosexuality rare.

    As for homosexuality in the animal kingdom, I will admit a lack of research on my part, but from what I understand homosexual encounters are usually ephemeral, with individuals still engaging in heterosexual breeding which would pass on genes. For humans this would be the case if for most of our history homosexuals still tended to have heterosexual encounters producing offspring. If this is the reason for the continuation of gay genetics, then a more accepting social atmosphere where gays feel less pressure to engage in heterosexual sex and adoption is more common than surrogacy there should be a reduction in the rate of expression of genetic homosexuality.

    This would all be irrelevant if, say, the gene responsible for homosexuality is actually widely expressed but is only activated in a small portion of carriers by environmental cues either in the womb or from social experience.


    I recommend http://en.wikipedia.org/wiki/Homosexual_behavior_in_animals

    Basically, any form of homosexuality you find in human, you can also find in the animal kingdom, including exclusive monogamous LTR.

    Next, admitting homosexuality exist from birth does not mean it's genetic. Personally, I very much doubt it's genetic. From the initial egg up to the newborn baby, a lot of stuff happen, not all dictated by genes.

    For example, I guess you assume gender (male/female) is genetic. While in fact, it's (in the general case) genetic... for human, but not for all animals.
    Turtles, and crocodiles, become male or female only out of the temperature during the development of embrio in eggs.

    A male turtle is physically different from a female : it has a longer tail, a concave belly and a big penis. Yet, it has the same chromosome as a female.
    You can't know the gender of a turtle using DNA sequencing, they don't have male/female gene difference.

    A turtle is usually born male or female, but it's not genetic. I think the same is likely true for homosexuality.

    So reasoning on gay gene propagation to explain homosexuality survival generation after generation is reasoning on unproven hypothesis.

    But if you like gene talk, the hypothesis is my former post is there is a set of gene for a 'machine' who will engrave our preferred sexual type in our brain as some point between as early as egg and as late as out first sexual interest.

    That 'recording forever sexual preference' machine will include a more or less large set of body type of our species, male and female, with a strong bias for opposite sex.

    I do think this imprint is done after birth, even if in the very first years, because a lot of straight men prefer women sharing some of their mother feature, and same goes for woman toward father type.

    It's not unlike imprint of bird, who follow the first moving object they see after aching as if it was their mother.

    I know it would feel better to think we exist because we are beneficial to society in general, and as such evolution keep us.
    But the truth is that sexual attraction is fluid in all the animal kingdom, so you can expect some very generic explanation to the fact.

    And I don't care if it makes homosexuality 'natural' or not, because nobody should have to find excuse for being what he is.

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    May 07, 2013 7:10 AM GMT
    I don't know what to think of this but good topic
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    May 07, 2013 1:36 PM GMT
    I'm sorry but I don't think I understand the question. Are you asking how did we get from

    here
    prokaryoticcell.jpg

    to here?
    17093983-funny-homosexual-heart-cartoon-

    Hypothetical: What if we are spiritual beings having a corporeal experience? Or for the less religiously minded, what if it isn't that consciousness only emanates from the mind--keeping in mind that there seems evidence of consciousness (whatever that is) in other animals besides humans and that some consider existing some sort of collective consciousness--but that consciousness precedes physicality, then would expressions of sexuality necessarily be entirely dictated by evolutionary forces?

    I understand an evolutionary purpose behind my drive to eat and to sleep and to house myself, but is there evolutionary reasoning behind my desire for one food over another or for one living situation over another. And that's not necessarily just a matter of preference. There might be some chemistry/anxieties that prevent me from functioning in crowded urban spaces and maybe that's triggered just by smelling other people nearby, just as an example. There are some foods I've tasted and spit out not as a matter of preference but they simply don't match my body chemistry and my body rejects them. Just like vagina makes me throw up.

    Must I require a reason of evolution to explain everything that might be systemic and not merely an aesthetic? Or do some happenstances of evolution just come along for the ride? Lucky us.
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    May 07, 2013 1:56 PM GMT
    CaCO3 saidIt would follow that countries with starving populations or those with high population densities would have more gays, but I don't think this has yet been observed in poor African or dense Asian countries.


    Yes but there is more social pressure to conform to cultural norms in those same places... a person may have (and act on) same-sex leanings, but will still get married and have kids because their family/community won't tolerate anything else.

    I think that is why there is such strong homophobia in such places... if a lifestyle other than the normal patriarchal model is accepted for one group, others will assert their "right" to deviate from it, too. We know plenty of straight guys who are not "family man" material, but we have a culture that has room for that.

    When I see a guy younger than me, with multiple whiny toddlers in tow, I'm not envious, I feel sorry for him. I wonder if half the commotion the Rick Santorums of the world make is less about the physical "ick factor" of guy-on-guy sex and more about "If I have to deal with this, you should too." I'm sure many of them would rather go to the gym four nights a week and be out clubbing on weekends instead of hitting Bed Bath & Beyond and changing diapers at 3 a.m.
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    May 07, 2013 2:15 PM GMT
    I think homosexuality is a fuck up in the genetic code and/or a fetal development fuck up.

    Either way I'm glad I'm a fuck up and wouldn't change it for all the tea in China.
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    May 07, 2013 2:16 PM GMT
    minox said
    CaCO3 said

    Evolution definitely doesn't produce perfect organisms, but mutations that seriously affect fecundity are usually quickly reduced to only rare expression. I wouldn't call homosexuality rare.

    As for homosexuality in the animal kingdom, I will admit a lack of research on my part, but from what I understand homosexual encounters are usually ephemeral, with individuals still engaging in heterosexual breeding which would pass on genes. For humans this would be the case if for most of our history homosexuals still tended to have heterosexual encounters producing offspring. If this is the reason for the continuation of gay genetics, then a more accepting social atmosphere where gays feel less pressure to engage in heterosexual sex and adoption is more common than surrogacy there should be a reduction in the rate of expression of genetic homosexuality.

    This would all be irrelevant if, say, the gene responsible for homosexuality is actually widely expressed but is only activated in a small portion of carriers by environmental cues either in the womb or from social experience.


    I recommend http://en.wikipedia.org/wiki/Homosexual_behavior_in_animals

    Basically, any form of homosexuality you find in human, you can also find in the animal kingdom, including exclusive monogamous LTR.

    Next, admitting homosexuality exist from birth does not mean it's genetic. Personally, I very much doubt it's genetic. From the initial egg up to the newborn baby, a lot of stuff happen, not all dictated by genes.

    For example, I guess you assume gender (male/female) is genetic. While in fact, it's (in the general case) genetic... for human, but not for all animals.
    Turtles, and crocodiles, become male or female only out of the temperature during the development of embrio in eggs.

    A male turtle is physically different from a female : it has a longer tail, a concave belly and a big penis. Yet, it has the same chromosome as a female.
    You can't know the gender of a turtle using DNA sequencing, they don't have male/female gene difference.

    A turtle is usually born male or female, but it's not genetic. I think the same is likely true for homosexuality.

    So reasoning on gay gene propagation to explain homosexuality survival generation after generation is reasoning on unproven hypothesis.

    But if you like gene talk, the hypothesis is my former post is there is a set of gene for a 'machine' who will engrave our preferred sexual type in our brain as some point between as early as egg and as late as out first sexual interest.

    That 'recording forever sexual preference' machine will include a more or less large set of body type of our species, male and female, with a strong bias for opposite sex.

    I do think this imprint is done after birth, even if in the very first years, because a lot of straight men prefer women sharing some of their mother feature, and same goes for woman toward father type.

    It's not unlike imprint of bird, who follow the first moving object they see after aching as if it was their mother.

    I know it would feel better to think we exist because we are beneficial to society in general, and as such evolution keep us.
    But the truth is that sexual attraction is fluid in all the animal kingdom, so you can expect some very generic explanation to the fact.

    And I don't care if it makes homosexuality 'natural' or not, because nobody should have to find excuse for being what he is.



    I definitely want to clarify that this thread comes only from my scientific curiosity, I have no desire to prove there is a justification for homosexuality, as I believe none is needed. Even if we all chose it, we should be free to do so.

    As for non-genetic causes, you need to remember that genetic expression isn't always straightforward but it is still genetic. The turtles for example, there is still genetic coding allowing for the male/female phenotypes and the temperature trigger mechanism is also coded. This is not to say that the genes "intentionally" chose this method of sexual differentiation, but that through their evolution this method was used by the most reproductively successful. Humans, for example, are genetically "male" or "female" based on XY chromosomes but we all have X so are all capable of expressing female traits (and all embryos start as phenotypical female). In fact, a mutation causing cellular testosterone resistance can cause a genetically human male to express a female phenotype (but sterile).

    Genetics is a complicated subject, and I agree there is probably not a gay "gene." It could be multiple genes and it could be in the baby or the mother or both. But at some point, some gene(s) somewhere must cause a hormone to be released or suppressed. Even environmental factors have a genetic component, where cells must respond in some way to a stimulus. If that response resulted in homosexuality and reduced fecundity, we'd expect those with resistance to that stimulus to become more prevalent. I'd go so far as to say that homosexuality MUST have SOME genetic component, even if that component is simply our genes not actively preventing it from happening.
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    May 07, 2013 2:21 PM GMT
    [quote][cite]CaCO3 said[/cite]
    2) Homosexuality increases the reproductive fitness of family units by adding extra resource acquisition capacity without increasing within-group male reproductive competition.[quote]

    How does Uncle Ungha redecorating the cave every 2 or 3 years "add extra resource acquisition capacity?"
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    May 07, 2013 2:27 PM GMT
    These evolutionary reasons don't take into account human culture, which is unique to the species. They look for direct equivalence with other animals, on purely a subsistence survival level. But as social animals, what if human culture and artistic pursuits are as important to us as other aspects of living? What if we crave other pleasures & stimulations besides food & sex? Then we might have:

    3) Homosexuality increases the quality of life of humans, while leaving breeding heterosexuals more time & resources to devote to raising their children.
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    May 07, 2013 2:28 PM GMT
    ART_DECO saidThese evolutionary reasons don't take into account human culture. They look for direct equivalence with other animals, on purely a subsistence survival level. But as social animals, what if human culture and artistic pursuits are as important to us as other aspects of living? Then we might have:

    3) Homosexuality increases the quality of life of humans, while leaving breeding heterosexuals more time & resources to devote to raising their children.


    People who blame us for the AIDS pandemic would vehemently disagree.