Heterosexual and bisexual siblings having kids with their opposite-sex partners also carry on the genes of homosexual individuals who don't have kids themselves.
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Homosexuality and Evolution
- Thread starter Flippypie
- Start date
Sexuality is simply way too complex to be determined solely by genetic factors. Which is not to say that it is a choice at all, either.
The OP raises some interesting questions.
So let's see... first, it is a significant oversimplification to assume that homosexuality would be disadvantageous from an evolutionary perspective. Spiders and fish survive mainly by breeding as much as they can and then leaving their offspring to fend for themselves. Humans can't afford to follow that same strategy; we are not ecologically viable if we breed too much and too fast, mainly because our continued survival depends so much on support from our peers and extended families. When human populations rise too fast they tend to anihilate themselves through conflict, famine and disease.
So right there you see that homosexuality is at least sometimes advantageous from an evolutionary perspective. It makes possible for communities to have a higher ratio of caretakers per infant in circunstances where that may well be the difference between extinction or continued survival.
I suspect it is also advantageous for the average human to be somewhat circunstantial in his or her sexuality, if for no other reason because that makes self-control that much easier. It is not generally advisable to be too forward and instinctive about out attractions towards other people, among other reasons due to potential jealousy and infighting.
The OP raises some interesting questions.
So let's see... first, it is a significant oversimplification to assume that homosexuality would be disadvantageous from an evolutionary perspective. Spiders and fish survive mainly by breeding as much as they can and then leaving their offspring to fend for themselves. Humans can't afford to follow that same strategy; we are not ecologically viable if we breed too much and too fast, mainly because our continued survival depends so much on support from our peers and extended families. When human populations rise too fast they tend to anihilate themselves through conflict, famine and disease.
So right there you see that homosexuality is at least sometimes advantageous from an evolutionary perspective. It makes possible for communities to have a higher ratio of caretakers per infant in circunstances where that may well be the difference between extinction or continued survival.
I suspect it is also advantageous for the average human to be somewhat circunstantial in his or her sexuality, if for no other reason because that makes self-control that much easier. It is not generally advisable to be too forward and instinctive about out attractions towards other people, among other reasons due to potential jealousy and infighting.
Since you ask:
- homosexual people can and do procreate.
- a sibling is just as good as a direct offspring for perpetuating your genome. Either one shares half your genes, on average.
- there are countless examples in the natural world of species that have some individuals that don't breed. Do you think the existence of, say, worker bees poses a problem for evolution?
- even if homosexuality is a disadvantageous trait for the individual (which is a big, undemonstrated "if"), it could be a consequence of an advantageous trait for the parent. We see examples like this all the time. For an extreme case, take salmon: to address the problem of predators, they lay thousands of eggs at a time. This is very disadvantageous for the many salmon fry that get eaten, but enough survive for this to be a workable strategy. If (pulling numbers out of the air) you could have 20% more kids on the condition that 5% wouldn't breed, then you personally be a more successful breeder than if you didn't take that deal.
- the bottom line: evolution weeds out disadvantageous traits. If you think a trait is disadvantageous but it persists, this is a sign that you don't have the whole picture.
... and in the process, have many offspring that will never procreate themselves, which I think is a relevant point in this discussion.
A spider that gets eaten before maturity has even less procreative potential than a spider that doesn't want to mate.
Flippypie
Lord of Controversy
My cousin is gay. I haven't ever really talked to him about it, so maybe I should. He's actually a Christian himself, and is a pastor at a church, so his worldviews are pretty similar. It would definitely be an interesting conversation.
That would not be a point against evolution at all. At least, not worse than extant sterility for some people today. Some people are sterile. They cannot possibly procreate. Some of this is genetic. Many others die before reaching the age of procreation also because of genetic or simple bad luck. Is that a danger to evolution? Hardly.
It would be a point against evolution if we were all gays, or sterile, while still prospering as a species for a million additional years. But as long as we kick 7 billions and counting, I do not see a problem. On the contrary. Naturally selecting a percentage of people for not having kids might provide stability in the evolutionary orbits in our species phase space.
And even if we turned all gays or sterile tomorrow, then we will get extinct like 99% of the species that walked earth.
You can abhor the thought as much as you want and accuse gays to facilitate our extinction.
But does that invalidate evolution? I don't think so.
Actually, the ones who think that gays are "against nature" are the ones who implicetely believe that evolution is true, even if they misunderstand how it really works. In general.
By the way, if you think that homosexuality is a choice, was it hard for you to choose not to be gay? Don't you think that a choice process, if any, makes sense only for bisexual people?
Ciao
- viole
Maponos
Welcome to the Opera
All the data for genetic and/or biological predispositions for homosexual behavior is becoming much more advanced today. There has been a very great study recently showing factors homosexual men show in common on the X-Chromosome.
I don't believe male bisexuality exists, though.
I don't believe male bisexuality exists, though.
... despite the existence of bisexual men?
Maponos
Welcome to the Opera
You can call yourself whatever you like, it doesn't change what you are.
Was that supposed to be responsive?
Maponos
Welcome to the Opera
It was, yes.
I've built my beliefs on my life experiences. All of the supposed bisexual men I have known are either homosexual and can't accept it or they have been bored heterosexual men.
I can't help but assume that there is an interesting story behind all this certainty.
There are no findings of any replicated study that indicate that sexual orientation in humans is genetically determined. A country-wide survey of adult mono- and dizygotic twins in Sweden, totaling more than 7,600 persons, found that shared genetics could at most account for only a very small portion of the variance. In men, heritability estimates for same-sex activity/attraction was 34-39%, and 18-19% for women: http://faculty.bennington.edu/~sherman/sex/samesex 2010.pdf
There is no evidence whatsoever that sexual orientation in humans is binary, i.e., comes in two discrete monosexual flavors: gay or straight. Indeed, all of the evidence contradicts the idea of binary monosexual orientation in humans. Unfortunately, the methodologies of all biological studies on sexual orientation (that I am aware of) are premised on the assumption that sexual orientation is binary.
On surveys when people are given choices beyond binary sexual orientation categories, such as on the Kinsey Scale or Klein Grid, a significant portion report sexual attraction, behavior, fantasies and emotional attachment that contradict exclusive heterosexuality or homosexuality. Even in recent decades, at least one survey has shown an increase in the percentage of adults reporting non-exclusive sexuality, and a decrease in the percentage reporting exclusive monosexuality. https://yougov.co.uk/news/2015/08/16/half-young-not-heterosexual/?
There is a good deal of historical and anthropological evidence contrary to the idea that sexual orientation in humans occurs as a binary of monosexuality. As recently as the late 20th century, exclusive monosexuality was basically nonexistent among the “primitive” societies of the Bedamini, Etoro, Kaluli, Onabasalu and Gebusi of Papua New Guinea. Elliston, D. Erotic Anthropology: "Ritualized Homosexuality" in Melanesia and beyond. American Ethnologist. Vol. 22, No. 4 (Nov., 1995), 848-867. https://wiki.geneseo.edu/download/a...rsion=1&modificationDate=1409074793507&api=v2
It is well documented that among the ancient Assyrians, Greco-Romans and Chinese--at least among upper class males--sexual relationships with both sexes was quite common. “Some cultures -- for example, the Assyrian and Graeco-Roman -- were very tolerant of homosexuality. The behaviour was practised openly and was highly prevalent.[5] Sexual patterns are to some extent a product of society's expectations . . .” http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1678219/pdf/bmj00033-0005.pdf Note that Baron’s use of the term “homosexuality” refers to “same-sex sexual activity”.
Sexuality and sexual orientation identity among modern Westerners is to a large degree an enterprise of erasure of innate bisexuality: http://www.jstor.org/stable/1229482?seq=1#page_scan_tab_contents
Exclusive monosexuality is also fairly rare and possibly even nonexistent among a variety of non-human mammals, including our closest living hominid relatives:
Stanford University biology professor Joan Roughgarden has also provided a great deal of information on sexual and gender diversity among animals (including humans) in Evolution's Rainbow: Diversity, Gender, and Sexuality in Nature and People. Publisher Weekly’s blurb says:
This brilliant and accessible work of biological criticism has the potential to revolutionize the way readers conceive of gender and sexuality in the natural world. Roughgarden, a professor of biology at Stanford University and a member of the Academy of Arts and Sciences, argues that the diversity of gender and sexuality one finds in many species suggests that evolutionary biologists of a strictly Darwinian bent are often misguided, since, according to Roughgarden, they erroneously assume a universally applicable gender binary in all species. The first half of the book brings that sexual diversity to light through innumerable examples among birds, reptiles, fish and mammals provided in highly readable anecdotes. The significance of this first section lies not only in this startlingly original portrait of nature, but also in how it suggests that contemporary Darwinian sexual selection theory is in part a result of cultural bias, since it "predicts that the baseline outcome of social evolution is horny, handsome, healthy warriors paired with discreetly discerning damsels." Roughgarden critiques this theory through an expansive study of biological scholarship, highlighting the frequent contradictions between such claims and the data used (and, she argues, manipulated) to prove them. The second and undoubtedly more controversial section discusses sexual diversity in humans. Taking as a given the presence in our own species of gay, lesbian, bisexual, transgendered, transsexual and intersex persons, she reads current scientific writing-on a supposed "gay gene," on gender reassignment and other issues-through a perspective that sees diversity as an advantage, not a handicap.http://www.amazon.com/Evolutions-Ra..._UL160_SR107,160_&refRID=0Q2SNDQAJGV1YGWY22EK
There is no evidence whatsoever that sexual orientation in humans is binary, i.e., comes in two discrete monosexual flavors: gay or straight. Indeed, all of the evidence contradicts the idea of binary monosexual orientation in humans. Unfortunately, the methodologies of all biological studies on sexual orientation (that I am aware of) are premised on the assumption that sexual orientation is binary.
On surveys when people are given choices beyond binary sexual orientation categories, such as on the Kinsey Scale or Klein Grid, a significant portion report sexual attraction, behavior, fantasies and emotional attachment that contradict exclusive heterosexuality or homosexuality. Even in recent decades, at least one survey has shown an increase in the percentage of adults reporting non-exclusive sexuality, and a decrease in the percentage reporting exclusive monosexuality. https://yougov.co.uk/news/2015/08/16/half-young-not-heterosexual/?
There is a good deal of historical and anthropological evidence contrary to the idea that sexual orientation in humans occurs as a binary of monosexuality. As recently as the late 20th century, exclusive monosexuality was basically nonexistent among the “primitive” societies of the Bedamini, Etoro, Kaluli, Onabasalu and Gebusi of Papua New Guinea. Elliston, D. Erotic Anthropology: "Ritualized Homosexuality" in Melanesia and beyond. American Ethnologist. Vol. 22, No. 4 (Nov., 1995), 848-867. https://wiki.geneseo.edu/download/a...rsion=1&modificationDate=1409074793507&api=v2
It is well documented that among the ancient Assyrians, Greco-Romans and Chinese--at least among upper class males--sexual relationships with both sexes was quite common. “Some cultures -- for example, the Assyrian and Graeco-Roman -- were very tolerant of homosexuality. The behaviour was practised openly and was highly prevalent.[5] Sexual patterns are to some extent a product of society's expectations . . .” http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1678219/pdf/bmj00033-0005.pdf Note that Baron’s use of the term “homosexuality” refers to “same-sex sexual activity”.
Sexuality and sexual orientation identity among modern Westerners is to a large degree an enterprise of erasure of innate bisexuality: http://www.jstor.org/stable/1229482?seq=1#page_scan_tab_contents
Exclusive monosexuality is also fairly rare and possibly even nonexistent among a variety of non-human mammals, including our closest living hominid relatives:
Stanford University biology professor Joan Roughgarden has also provided a great deal of information on sexual and gender diversity among animals (including humans) in Evolution's Rainbow: Diversity, Gender, and Sexuality in Nature and People. Publisher Weekly’s blurb says:
This brilliant and accessible work of biological criticism has the potential to revolutionize the way readers conceive of gender and sexuality in the natural world. Roughgarden, a professor of biology at Stanford University and a member of the Academy of Arts and Sciences, argues that the diversity of gender and sexuality one finds in many species suggests that evolutionary biologists of a strictly Darwinian bent are often misguided, since, according to Roughgarden, they erroneously assume a universally applicable gender binary in all species. The first half of the book brings that sexual diversity to light through innumerable examples among birds, reptiles, fish and mammals provided in highly readable anecdotes. The significance of this first section lies not only in this startlingly original portrait of nature, but also in how it suggests that contemporary Darwinian sexual selection theory is in part a result of cultural bias, since it "predicts that the baseline outcome of social evolution is horny, handsome, healthy warriors paired with discreetly discerning damsels." Roughgarden critiques this theory through an expansive study of biological scholarship, highlighting the frequent contradictions between such claims and the data used (and, she argues, manipulated) to prove them. The second and undoubtedly more controversial section discusses sexual diversity in humans. Taking as a given the presence in our own species of gay, lesbian, bisexual, transgendered, transsexual and intersex persons, she reads current scientific writing-on a supposed "gay gene," on gender reassignment and other issues-through a perspective that sees diversity as an advantage, not a handicap.
Rainbow Mage
Lib Democrat/Agnostic/Epicurean-ish/Buddhist-ish
Since everything about a person's attractions, even presumably bad ones, are genetic. Several preferences a person has can be genetic. Even inclination to certain foods. If heterosexuality were not genetic and part of evolution it would not exist. Is there a reason people need to think homosexuality is genetic, but not heterosexuality?
I see no reason to believe that biological determinism is true. I don't think any sexuality is genetic.
Rainbow Mage
Lib Democrat/Agnostic/Epicurean-ish/Buddhist-ish
Well you're free to think that. We all have opinions.
Shadow Wolf
Certified People sTabber & Business Owner
While studies suggest something is going on at the genetic level, none of them show it's entirely genetic (and in fact there is yet to be a consensus reached as to the exact causes of sexual orientation). Abuse as a child, for example, is an environmental factor known for having the potential for shaping such things.
The emphasis on homosexuality is probably nothing more than the fact than we have long perceived it as a sort of otherness. Be it something sinful, a mental disorder, or just "them," we tend to not look to much into something unless there is something noticeably different.
I tend to think that humans are basically just sexual opportunists and that all people at least have the potential to be pansexual, but that culture interferes with our perceptions and expectations of our own sexuality too much, so most people restrict themselves.
Where did you get that idea? Cite the evidence. It must mean that the Swedish twin study noted above is wrong. Where did it go wrong?
You are conflating procreation with the sexual orientation of heterosexuality here. I have a son. Apparently you would count him, or would count that fact, as evidence that “heterosexuality is genetic and part of nature”. But I’m married to a man, and was in a relationship with another man when my son was conceived. Obviously the production of offspring does not prove the existence of the sexual orientation of heterosexuality, much less that heterosexuality is “genetic”.
Couldn't have said it better.