This is a nice, short summary of some of the explanations for the evolution of homosexuality. It could be shorter; there are really just two classes of explanation, the adaptationist strategy of trying to find a necessary enhancement to fitness, and the correct strategy of recognizing that not all attributes of an individual organism are going to be optimal for that individual’s reproduction, so don’t even try. Love isn’t hardwired by biology, and it can go in all kinds of different directions.
So I’m saying the best answer in the list is #5. I wouldn’t be biased by the fact that the author is quoting me, no, not at all.
So, we’re not blaming our moms anymore?
http://www.theregister.co.uk/2006/04/24/pink_flamingos/
Gay flamingos strike long-term relationship
Carlos and Fernando: model pink parents
Strange that the latest hypothesis isn’t mentioned. There is a published correlation between the occurrence of homosexual men and the occurrence of women who are more fertile than usual in the same family. This looks like the same (unidentified) gene/s are involved in both traits, and that the evolutionary advantage of higher female fertility outweighs the disadvantage of reduced male fertility, so the allele stays in the population. Male homosexuality as a genetic byproduct.
No such studies seem to exist for female homosexuality.
Strange that the latest hypothesis isn’t mentioned. There is a published correlation between the occurrence of homosexual men and the occurrence of women who are more fertile than usual in the same family. This looks like the same (unidentified) gene/s are involved in both traits, and that the evolutionary advantage of higher female fertility outweighs the disadvantage of reduced male fertility, so the allele stays in the population. Male homosexuality as a genetic byproduct.
No such studies seem to exist for female homosexuality.
@PZ: I see how love can be hardwired since it leaves us with relatively monogamous relationships in which the male contributes more to raising the child, improving thus the survival of its genes.
@David Marjanović: This is an Italian study that was published, if I’m not mistaken, about 1 1/2 years ago. I amn unfortunately unable to find it on PubMed right now. Although it sounds compelling I do have some reservations to studies like these. Is there really a causal connection or do some environmental aspects come into play?
What’s the evidence that homosexuality has a significant genetic component? As far as I know, there is little agreement that genetics plays a large role, so why try to look for an evolutionary explanation? Isn’t that putting the cart before the horse?
I’m a little wary of anything that assumes homosexuality and reproduction are mutually exclusive. In other species, yes, but humans have separated recreational and procreative sex.
What about the theory that it’s caused by hormone washes and other factors during pregnancy? Has that idea been completely dismissed?
These possibilities are all about male homosexuals. How do you suppose women become homosexual? I’m straight myself (so I’m mostly guessing) but I imagine lesbians get their sexuality through different routes than do gay men.
Heterozygote advantage (balancing selection) is an interesting theory.
Of course, it would be unlikely to be a single gene, but we could imagine a collection of loci (a “meta-gene” if you will).
Gonna use a whole bunch of improper terms and avoid things like “K factor”
In groups where there is a selective need for larger amounts of individuals, but there is a counter selective need for a decreased amount of offspring, as a carry capacity cannot handle all individuals breeding at the same rate, there are numerous possible outcomes.
Some is just a decrease in the overall reproductive ability off individuals, but this can be problematic for groups recovering from a severe loss of numbers.
Wolves take another path where they have Alpha male and females that are the individuals breeding, and the rest refrain. This helps the pack in the above loss of numbers situation by allowing a pack to spread out and make separate packs in times of trouble where parts of pack that refrained before start to breed increasing numbers quickly…
Another situation is the alpha male, and a group of “his” females, where the other males are supposed to refrain. We come from a possible evolutionary background of this behavior, but it has sorta lost its hold and mutated into our weird Sports-rockstar-Idol worshiping behavior that we waste so much time with.
Another behavior that helps is the “Worker”, where not all individuals breed, so the numbers of the “pack” are not reflective of the numbers of possible new births. We see this mostly in insects, but also in Naked Mole rats and such…
We mix a strategy of extreme input into offspring, mixed with an increased output of offsprings relative to our close kin the other great apes. Personally, I believe, due to grooming as a behavioral trait in the great apes, selection events where decreased percentages of individuals breed strategies, used grooming and sexual prefers as a point of increasing numbers of the troop relative to the breeding output possibility.
If these ideas are correct, we should see these varied traits in larger social groups where fitness is measured by population fitness more than individual fitness (as based on individual reproductive success).
Molly wrote: “I’m straight myself….”
Not that there’s anything wrong with that.
Let the Seinfelding begin!
Molly said:
“”These possibilities are all about male homosexuals. How do you suppose women become homosexual? I’m straight myself (so I’m mostly guessing) but I imagine lesbians get their sexuality through different routes than do gay men.””
I have never met a man that was attracted the men, and was not gay. I have met a great deal of women who are attracted to women, and do not consider themselves gay at all.
There does seem to be a double standard here. There is only, in my experience, one type of gay guy, as in gay…or not gay. But in females, there seems to be many shades, with 2 general types. Straight women, who are sexually attracted to females for sex alone but desire men for actual relationships, and actual Lesbians who are only attracted to females, and do not care for an emotional relationship with a men ever.
There is a third possible type I would like to mention that South Park was using when they made fun of the Movie 300 recently. This is the “Late in life” Lesbian. This behavior seems to evolve over time, as a woman starts out like the above standard woman who will have sex with a woman, but does not sesire a relationship with one, and, over time, loses their emotional desire to be with a man, while growing emotional attachments with women.
I believe these are all part of the social fitness strategies I tried to describe above, where the fitness is measured, not by individual reproductive success, but by the ability of the population as a whole to survive, and produce viable young, which may or may not always be the same thing..
Also, it is just cool to watch two chick make-out
They left out what I think are the most compelling arguments. Gay siblings are “back-up” caretakers for his sisters’ children should she die in childbirth, and the gay siblings also prevent alpha male infanticide when a new alpha male takes over.
I think preventing alpha male infanticide is the most important reason, and countering that is the reason for homphobia. Who are the most homophobic individuals? Those who subscribe to religions dominated by patriarchs (alpha males). Many of which had multiple wives and concubines. Moses even preached alpha male infanticide (Nimbers 31.17-18).
Adherents of patriarchial religions object to gay men because they can thwart their reproductive strategy of alpha male infanticide.
Our culture imagines homosexuality as a all or nothing. We tend to imagine that one either has sex with people of the same sex, or not (especially, as in the response above, for men). But historically, and in other cultures, that’s not always been the case. One might have sex with people of the same sex, AND have sex (with the potential of reproduction) with people of the opposite sex.
As long as one has hetero-sex enough to reproduce (which doesn’t necessarily have to happen often) AND those kids make it to the next generation to reproduce, then there may be all sorts of benefits to having homosexual relations.
And there may be all sorts of benefits to barbequeing. Just to re-iterate before the discussion spirals off into the “Just-So” stories that seem inevitable in sociobiology, what is the evidence that sexual orientation has a major genetic component, and thus even needs an evolutionary explanation? Given the vast cultural differences both currently and historically in the apparent prevalence and societal acceptance of homosexual activity, my guess is that many manifestations are largely determined in humans by social factors, and not genes.
(I also think it is a very good point that it isn’t clear that “homosexuality” itself is a unitary phenomenon, especially as manifested in women versus men, but even within the genders.)
Correct me if I’m wrong. As I understand it, when times are tougher and natural selection peels off more members of the population, the remaining members show greater uniformity. When times are good and more members of the population get to stay in the pool, there’s a bit more drift. It’s not like everyone is under such pressure to ‘optimise’, so nature can try some ‘experiments’ and let things move around a little. So if homosexuality has an evolutionary basis at all, could it be seen as a side-effect of this drifting?
I can’t understand why the arguement over whether people are “born that way” or “made a choice of lifestyle” has any relevance.
I don’t see what difference it makes, nor is it any of my business.
My only concern is how a person chooses to conduct themselves in their relationships. And that only concerns me when their behavior is violent or exploitative, (modes not unknown to heterosexuality) because that may hurt or kill others.
The only other concern I have is my self-respect, which demands that I treat others with respect, regardless of how they got, or chose to get “that way”.
I have known gays (some of my best friends are gay, not that there’s anything wrong woth that!) who have insisted they were gay from the moment of birth, (when they made a pass at the obstetrician?) and others who “decided ” they were gay after a long marriage and raising several kids.
All that matters to me is that people, gay or straight, work out their needs in a non-violent, non-exploitative, hopefully even mutually satisfying and productive way.
I’m straight myself…
Gosh, I’m glad I’m not that sure about it! Besides, I know several people who swithced orientaions after a blow to the head. And anybody could slip and fall in the shower, and bam, you’re a raging queen, or the opposite! There are other, more insidious things, that can cause a switch, too. Why do you think the NBA got rid of those real skimpy shorts and went to those big, baggy outfits they wear? One wrong camera angle and a thousand guys run out and get fitted for a sequined gown!
I concur with Molly, that there may be a different route for gayness in men vs. gayness in women—-(heh) not that there’s anything wrong with that!
At the same time, I don’t see any reason to jettison adaptationist explanations for homosexuality. Pinning human behaviour on contingency, it seems to me, was just Gould’s way of saying ‘I don’t want to talk about that, because I don’t like where that kind of thinking leads to.’ It just seems to me that retaining a certain amount of plasticity in sexual response is likely to be adaptive in the long run, similar to the norm of reaction for other traits, and I’m OK with that….SH
One thing that seems to be missing here is that many tribal societies are/have been – in additional to alpha-male/harem dominance – structured as separate male/female groups.
One recognized consequence of this is in ‘induction’ ceremonies where a boy child joins the males… In many such groups homosexual sex between men – when in the male group – is both normal and expected, and occasionally forms part of the induction ceremonies (as a way of preparing boys to become men).
The same is (observed to be) true in the female groups, where homo-sex is a bonding ritual, as much as (or more than) it is a sexual act.
I don’t have access to the relevant journals (not an academic, sorry) but I do recall specific (and fairly recent) papers regarding New Guinea tribes, among others.
I’m almost sure this is also ‘common knowledge’ at least among people who ‘devoure’ anthopology.
It just seems to me that retaining a certain amount of plasticity in sexual response is likely to be adaptive…
With me it’s cash only. No plastic! I say, get the lucre filthy or not, in hand before you consider switching.
What about adaptationist explanations for soccer? Or for opera? Or for birthday celebrations? Or for business suits? Why think that there is even a need for an adaptationist explanation until it is shown that there any significant genetic component to the (wide variety of this) behaviour?
Perhaps I’m oversensitized to this, having worked in psychology during the heyday of sociobiology, but honestly, if there’s no strong evidence for a major genetic influence, asserting adaptationist explanations is simply unwarranted evolutionary psych triumphalism, and not science.
papers regarding New Guinea tribes…
They’re the ones who wear those outrageous “penis sheaths”! God, I love those guys! I’d pay just about anything to get one of those so I could wear it around the house, for the edification and amusement of my wife.
Ohmigawd, the local nursery has bamboo canes for sale!
See ya later, folks, I’ve got some sheathing to do!
DO they make bamboo canes in ‘big-as-a-horse’ size?
Apparently there is some limit to the number of times ‘sex’ can appear in the text
Sorry — still british…. Read the ‘Nursery’ thing again and had an image of a kindergarden class (‘nursery class’ in the UK) making penis sheaths on crafts day.
I.must.be.sick (or unapologetically normal!)
Love isn’t hardwired? Bwhahahaha!
Anyway… Since homosexuals tend to have fewer children than heterosexuals, one question to ask is whether homosexuals confer an adaptive function upon their kin.
A possible answer is found in the consistent finding that latter born males are more likely to be gay. This is an unsurprising conclusions as it behooves the family to limit sexual competition between male offspring. Alfred is the stud male, Brad and Charlie his heterosexual backups, while Dale and Edward are their homosexual, familial compatriots. And to what advantage? The heterosexual males gain the strength of brotherhood without risk of sexual conflict. The homosexual brothers don’t directly pass on their genes. Rather, they indirectly do so by strengthening the family unit and increasing the genetic success of the patriarch with whom they share significant genetic commonality.
Allow me to clarify one thing… I’m not arguing that homosexuals are “caregivers” in the nanny sense. I’m arguing Alfred needs strong, powerful brothers if he and his tribe/family are to succeed… and yet it wouldn’t be good for the Alfred – and for that matter the tribe- if all males were competing for each others mates.
Tulse… If you doubt the existence of strong evidence for a major genetic influence over homosexuality, you’re heads been buried for the past 20 years. For a simple overview, look at The Science of Gaydar in New York Magazine.
I see we have a blank-slate fossil in our company.
How were the 60’s anyways?
Did you go to Woodstock?
Mooser wrote
I agree, that as far as how we should treat people, the cause of homosexuality is irrelevant. But I don’t think that’s the argument going on here. This is just an interesting scientific question.
Thank you, Tulse, for being a persistent voice of reason.
These discussions are always so full of false dichotomies and simplifications as well as just-so stories…it gets tiresome.
Some important points that must be considered:
1.) Genetic vs. choice is a false dichotomy. Environmental effects on development can be very important in organizing behavioral pathways (somebody above mentioned “hormone washes” for example).
2.) Homosexual behavior is not the same thing as homosexuality. There are well-known environmental influences on the expression of homosexual behavior (rates increase in sexually segregated situations like prisons, boarding schools, women’s colleges and, perhaps, the societal conventions referred to above re New Guineans). The explanation for that is probably (as PZ suggests) found in the basic plasticity of human sexual behavior. Some people get off on shoes, sheep, squid, smoking, latex, and/or cucumbers, but everyone would laugh if one suggested an evolutionary explanation for those examples…whenever and however sexual proclivities are organized, there is undeniable flexibility built in.
3. Two male birds raising a chick is neither homosexuality nor homosexual behavior; as far as I know it occurs only in species where 2 parents are required to fledge successful young, and it simply suggests some flexibility in pair-bonding and parental behavior.
4. The conundrum in accounting for homosexuality in an ultimate evolutionary sense applies only to the (undeniable) exclusive sort of homosexuality (including exclusivity in both proclivity and behavior) seen (AFAIK) only in humans. Behavioral plasticity is a different phenomenon requiring different explanations.
I’ll also add that the kind of hand-waving naive appeal to group selection evident in the last paragraph of the linked post and some of Lago’s comments above make my stomach hurt.
Actually “caretaker” in the nanny sense is exactly the point. Who is better at “home-making”? A straight guy or a queer guy? Didn’t the “queer eye for the stright guy” demonstrate that there are lots of gay men who have better “nest building” skills than lots of straight men?
If the only way that gay men could reproductively benefit is by being good foster parents for their sisters’ children, then “eventually”, “good parenting” genes would become linked to the “gay” genes.
Straight men reproductively benefit by killing other straight men first and getting females pregnant as much as possible.
Having a gay son might be a better reproductive “bet” than having a straight son who is an “alpha male want-a-be”, and who gets killed by fighting another alpha male to the death before having the chance to reproduce. A gay son will protect the neices and nephews his sisters have. That is why I think the “gay” genes are on the X chromosome.
just so.
Ompus: took a quick skim of the article you linked–pretty interesting. But please realize that phenotypic correlates and even biiological determinism DO NOT NECESSARILY MEAN “GENETIC.”
Sven
Are you claiming Homosexuality is a “learned” state? For that matter, are you claiming Heterosexuality is as well?
Gay roundup
From the title, I was expecting something like this:
http://tinyurl.com/3x8oad
I don’t have any expertise in any of the relevant fields, so my opion’s worth about as much as a share of Enron stock, but here’s my take on this issue.
Sexuality, seems to be somewhat innate, but like most behaviors, is also plastic. I would also guess that the innateness is a combination of genetics & other influences during development. In as far as sexuality is controlled genetically, I can see bisexuality as being very advantageous to our species, since humans use sex for bonding as well as reproduction. As Tony pointed out, there are several known cultures where bisexuality is the norm. You can also see this in our close evolutionary cousins, the bonobos. I would also guess that our sexuality is influenced by several genes, so I don’t see it as too implausible to see homosexuality as being partly the result of certain combinations of those genes.
I also wonder how many people really are 100% heterosexual or 100% homosexual. I know several gay men who have biological children, so obviously they’re not so repulsed by the idea of having sex with a woman that they’d never do it. I don’t personally know any gay women (at least not any that have told me they were), but I wouldn’t be surprised if it was the same case for them. In other words, 100% homosexuals (and probably also 100% heterosexuals) would seem to be very rare. So, if normal human sexuality is considered as a combination of homosexual & heterosexual tendencies being influenced by several genes, a handful of outliers at either end of that spectrum doesn’t seem to be much of a problem to explain by evolution.
I also question Sven’s assumption of exclusive homosexuality being present only in humans. We have a pretty large population size to study with humans. If exclusive homosexuality is exceedingly rare, given the small populations of some of the other intelligent social animals (chimps, bonobos, elephants), such a rare trait might not occur very often. I seem to recall reading something not too long ago about finding that type of sexual behavior in rams, though. Then again, I could be completely off base on this whole thing.
Scott Hatfield up on comment #19 argued that “retaining a certain amount of plasticity in sexual response” is “adaptationist explanation for homosexuality.” My question is why is an explanation for our plasticity an explanation for homosexual behavior?
Isn’t there a difference between explaining why we have agency to choose our sexual behavior and explaining a particular sexual behavior? Once we have an explanation for our adaptability to environmental pressures of different sorts, can’t the explanation for particular behaviors become entirely social or cultural?
It’s a fallacy to assume that “love” is the default state. How many other mammals fall in love? Most other primates simply mate when the female comes into heat.
My own theory regarding “love” and emotional attachment is that it’s a vestige of the parent/child bond chemistry, a byproduct of our neoteny, evolving as a useful reproductive strategy as emotions replaced estrus as a motive to mate. However, (and this is the important part) love and sexual attraction were often not the primary motive for marriage and reproduction. Cultural mandate was. Marriages arranged by parents is often the norm in many cultures.
One of my own theories regarding homosexuality is that there isn’t any evolutionary “reason” or “benefit” for it; it’s simply a byproduct of the reduced stabilizing factor caused by reproduction by cultural expectation. If cultural expectation and not sexual preference becomes the major driving force behind reproduction, then we can expect a less uniform pattern of sexually-driven behaviors. The reason homosexuals survive in today’s world is because of the fact that we’re a civilized society where individuals are valued for contributions beyond reproduction. OTOH, in other /older tribes and cultures (including Old Testament tribes), the penalty for homosexuality was often death (or rather, being caught in a homosexual act… could this have been an ironic reason that compelled homosexual men to marry and reproduce?)
Until the righties get ahold of in order to find a “cure.” Then again, such a “cure” could hardly be more cruel that what psychiatry/psychology did to us in the middle parts of this century.
There again is the issue that there are “absolutes” in sexuality and that one is either gay or straight. Actually according to Kinsey’s chart if plotted on a bell curve, then most people have varying degrees of erotic empathy toward their same sex with few occupying distinctly total hetero or homo sexual FEELINGS (Behavior, however, may be repressed or surpressed).
I’m not stating that everyone is bisexual in the sense that they are ambivalent to one sex or the other and would couple willy nilly with either sex if the opportunity arose, rather that most people do have a prevalent desire for one sex or the other and that most TRY to be exclusively heterosexual if not monogamous. (This gets dangerously into that “choice” cunundrum that religion seems to obcess upon).
It’s not a problem, for lack of a better word, for those who are mildly or rarely attracted to same sex but those who are closer to the center of the Kinsey scale, and those who identify with heterosexual desire but are more desire toward certain members of their same sex. These are the people who struggle with free will vs biology/genetic issues in a society that views homosexuality as immoral or at least a negative trait. In our society their are many with little to no heterosexual desires who marry and assume the guise of straight men and women due to cultural pressures and the overwhelming sense of failure if they give in to their true natures. Yet, a biological explanation would do little for these people if they still buy into a moralistic view of free will.
Religious and cultural biases tend to promote attitudes against any ambiguous behavior in men. The implication is that any homoerotic tendency negates masculinity and what it is to be a man; however if you are familiar with the “bear cult” (google it at your own risk) muscle bears, truckers, leather men and other hypermasculine gay subculture, then the image of girly men and twinks becomes cognitively dissonant. Not all men who identify themselves as gay secretly wish to be girls or queens.
The bias against any homosexual behavior is instituted culturally in early childhood, the result is a huge number of people, compelled by self loathing and fear, who are unable to state authentic claims about their true nature. We learn to “tolerate” homosexuality because it is PC, and to denyany inate same sex feeling for fear that it will lead to a “Bi now, gay later” slippery slope.
Yet, there are people who we identify as being distinctly “gay” because of certain physical traits that identify them as being masculinized women and feminized or androgynous men. This is more likely due to maternal hormonal fluctuations in utero and so it is assumed to be biological rather than purely genetic, unless the reason for the fluctuations are genetic. We also must remember that gender identity and sexual preference are not the same thing.
We also ignore one other point; sexual play among primates is not strictly reserved for procreation. Strict hetero/homosexual play amoung many differnet animal groups is not the norm (ask anyone who grew up on a farm). Dominance/submission, social ranking, affection can assume the guise of sexual play among same sex groups. Gender segregation can also bring about homosexual behavior as jargon used in penal culture, “LURD” and “GURD” ( Lesbian/gay Until Release Date), attests. and then there is the Greek culture in ancient times, need I say more?
I leave you with graffitti observed on a bathroom wall: “My mother made me a homosexual!”.
Underneath someone scrawled, “If I give her enough yarn, will she make me one too?…”
Face it, when it comes to men, “A little gay” is like saying, “A little pregnant.”
Our sexuality is as innate as in other animals. Just because your dog humps your leg, it does not mean he is gay (if you are male) or he is into bestiality (The beast being you).
Face it, “plasticity” of behavior does not negate that same behavior being instinctual.
Lago, I don’t understand how a behavior can be both “instinctual” (whatever that means) and also the result of the agency of the organism. Could you clarify?
I’d imagine it is because of the relative dangers in expressing same sex desires/attractions between the sexes. It is much more dangerous for men to say they are attracted to another man than it is for a woman.
What you’ve described here are the Ted Haggards of the world – those who are attracted to men, but unwilling to admit it. Thus they become the homophobe instead.
Don’t see a lot of gay people commenting here, but let me just chime in with a few random thoughts.
There was some mention of people who switch sides. I’d say be careful of that if someone switches from straight to gay, but not the other way around. There’s tremendous social pressure to try very hard to be straight. There really isn’t any pressure the other way. And even though some people seem to choose, I can tell you from my own personal experience that it was not a choice. Not that this tells us it is genetics vs. environment.
On looking for a genetic cause – personally I don’t see any other way to get the religious jerks off our backs. So long as they can pretend it is a behavioral choice we will be considered sinners. So we might not have any specific evidence that indicates we should be looking for genetic causes, I feel we have some very strong social incentives for looking there.
“Sven: Are you claiming Homosexuality is a “learned” state? For that matter, are you claiming Heterosexuality is as well?”
Nope. I merely point out that there are other (“epigenetic”), purely biological origins of phenotypic diversity than DNA-based genes. Developmental environment, for example.
On the other hand I see no reason to dismiss a possible role for learning (=/= “choice”) in influencing the expression of behavioral phenotypes.
“I seem to recall reading something not too long ago about finding that type of sexual behavior in rams”
you know, that rings a bell. I hope somebody else can find a reference because I HAVE to get these fucking exams graded.
gex: I am all in favor of looking (i.e. testing the genetic hypothesis). I just find nongenetic explanations more compatible with my biological worldview. I have certainly been surprised before, however!
The antidote to just-so is DATA.
Republican politicians are going to find that they are not abnormal.
Dugan’s Deli, Ames, IA?
I didn’t read all the comments. Sorry if I repeat someone.
Number 5 (PZ’s favorite) seems somewhat silly now that I think about it. If that were true, wouldn’t that mean that EVERY male (and female) has same-sex attractions? it wouldn’t account for exclusively gay people, or the variation of sexual attractions there is. Everyone would have to be the same because (just like everyone has nipples), mutations would harm the other sex too much.
I have never met a man that was attracted the men, and was not gay.
Lago, meet… well… me. I’m a man attracted to men, but I’m not GAY. I’m mostly gay. I’m also attracted to girls (admittedly far, FAR less often than guys, but I can’t ignore them). I know others who are less gay than I am.
So, the two guys that Penn and Teller found to come on their show about this subject, who decided to both get tit implants, because they liked tits, but where usually exclusively gay with each other, but where one said, “But if you are a women, we can still rock your world!”, are what exactly by your silly definition of what men *must* be if they have attractions to the same sex? I would almost suspect you of being a Ted Haggard type, who is trying to find some excuse for *yourself* that will let you claim you have never felt an attraction to other guys. But, what do I know, I am just some fool that reads articles and watches programs on the subject once in a while, not someone like you, who is *certain* about how it all works. lol
Lago write:
If you consider “plasticity” to be “blank slate”, then I suppose you’re correct, but that description would seemingly encompass our genial host as well.
OK, too many questions…
I too do not believe the evidence shows “gayness” to be a directly inherited trait (as in, there is a gene for it). I do believe the evidence is quite strong for it being due to a developmental environment (in the womb, not in society)
Most people believing in a “Blank Slate” like to define humans as without instinct, hence the name “blank”. The general reasoning used is that, if a behavior can be modified, as in being “plastic”, then it is not a true instinct. This is BS.
Dogs hunt, yet we can modify this behavior into a herding behavior for farmers. I trained my Iguanas to go to the bathroom on papers, or in the tub if they desire a shower as well. This is certainly not a “natural” condition. I have had my cats trained to leave my pet mice alone, as well as leave birds alone that I was helping who had broken wings. This does not indicate that cats are not instintually bird and rodent hunters.
We laugh, we cry, we desire, but the things that we do, can be modified to a great deal by society. Does this mean laughing, crying, and desirering things is not innate in us? I doubt it.
And just because a person has done a homosexual” act in their lives, does not make them gay, but the same goes the other way, as in just because Ted Haggard desires to be his social version of, “The Norm”, does not make him straight.
No one freakin’ taught me to like tits. I just do.
Face it, when it comes to men, “A little gay” is like saying, “A little pregnant.”
Man, this poor reasoning at it’s most illogical and about as intellectual as the “God made Adam and Eve not Adam and Steve” argument.
Identifying oneself as gay or straight, or for that matter omnisexual, is not the same as behaving sexually. Many men on the down low never identify themselves as gay or bisexual. Many men who have had only homosexual experiences do not identify themselves as gay, in fact, many identify as straight with no sense of irony or deception. They don’t see themselves as the stereo typical gay person. Just as many people have had samesex relations in High School and College assume strictly heterosexual relations hips afterward and may identify as bi or polyamorous. What constitutes identifying as “gay” or “straight” is ultimately relative. Qualifying and quantifying behavior under labels scientifically is a different story.
A favorite joke: I fix pipes for my neighbors… so you’d think they’d call me” Bob the Plumber.”
I’ve built dozens of houses… so you’d think they’d call me “Bob the Housebuilder.”
But you suck one cock…
Right, which means that, without further evidence of such direct genetic influence, it is a bit silly to look for adaptationist explanations.
Perhaps, but such explanations are clearly incomplete, as they would have to account for why there are (and historically have been) large societal differences in the prevalence and expression of homosexual behaviour.
Right, which means that the phenomenon being addressed is far more complicated than, say, eye colour. I don’t think that we’ve had a formal operational definition of “homosexual orientation” in this discussion, and while I don’t know the literature extremely well, I’m not sure there is even a standard definition among researchers.
Does any psychologist still use the term “instinct” to describe human behavior? I doubt it.
I also think the characterization of “the blank slate” is just wrong. Pinker, and Tooby and Cosmides before him, constructed this blank slate made of straw and thrust it onto unnamed social scientists and declared it the “official” social science model of the mind.
For example, Pinker in his dreadful book THE BLANK SLATE claims that anthropologist Alfred Kroeber (whom he misidentifies as “Albert”) claimed that heredity has no role in shaping human behavior which is simply not what Kroeber maintained when he wrote, “Heredity gives us the slate and the pencil in good working order. Our individual kinds of slates and the sharpness of the pencils are also wholly from heredity. But with the writing on the slate, which is the part we play in civilization, heredity has nothing to do.”
Whether or not the variance in human sexual preference is primarily genetic or environmental, we are still left with the evolutionary question of there is as much variance as there is. In other words, why haven’t we (or for that matter, most other species) evolved an absolute preference for a mate of the opposite sex, given that alleles that favor such a preference would seem to be subject to strong positive selection based upon increased reproductive rate?
{No one freakin’ taught me to like tits. I just do.}
You would’nt believe how many gay men and straight women love tits. In fact most gay men love pretty ones (no bananas, snow cone cups or silicone bags so huge that you fear contact with sharp objects or heat sources). It’s what lies blow that creates the rub…
Lago said: “I too do not believe the evidence shows “gayness” to be a directly inherited trait (as in, there is a gene for it).
Tulse responds “Right, which means that, without further evidence of such direct genetic influence, it is a bit silly to look for adaptationist explanations.”
Quick, tell me the genes involved in heterosexuality in Cattle? Mice? Dogs?
I guess there must be no adaptive explanation for this odd behavior in these animals I guess..
I said: “Face it, when it comes to men, “A little gay” is like saying, “A little pregnant.”
Someone not understanding my post responded:
“Man, this poor reasoning at it’s most illogical and about as intellectual as the “God made Adam and Eve not Adam and Steve” argument.”
If you thought your response was a logical one to the many statements I have given above, you surely are clueless to what I said…
(Whether or not the variance in human sexual preference is primarily genetic or environmental, we are still left with the evolutionary question of there is as much variance as there is. In other words, why haven’t we (or for that matter, most other species) evolved an absolute preference for a mate of the opposite sex, given that alleles that favor such a preference would seem to be subject to strong positive selection based upon increased reproductive rate?)
It’s because primate/human sexuality is not solely for the purpose of PROCREATION. If sex in primates/humans were ONLY for reproduction then homosexuality would be a dead end (so to speak) on an evolutionary basis. Few men who describe themselves as gay are completely impotent when it comes to being able to penetrate and ejaculate in a vagina. Lot’s of gay dads around, you just have o know where to look.
There are many gay men who have children through the usual means -coitus with a female. They may have trouble at times to become aroused but many can complete the act.
Sorry Lago, I did misunderstand you. Where are those damned emoticons when you need one? “When it comes to men…” ah yes, I see. My bad
Let me try one more time
“Gayness” is not “directly” genetic, but is possibly secondarily brought about by genetics that, in certain conditions, bring about a particular set of environmental pressures on a growing fetus.
How do such traits stay? Are they just developmental oddities, like an extra thumb?,,, Homosexual behavior is found in our close relatives, so, the behavior at least, seems natural to some degree or other
Why has homosexuals stayed so constant in the population? Or have they? …As far as we know, there has always been a small percentage of society that was “gay”. Knowing the amount over time is close to impossible, but it always seemed to be on the small percentage side…
Does homosexual activity make one gay by the acts alone? Simply put, no.
Are their people that have homosexual relationships that do not “feel” gay? Yep, I have met a few actually.
Are there people that act as heterosexuals, but are gay? Cough Cough, Ted Haggard, cough cough…
If “gayness”, as in an actual set desire for the same sex is there, how did it not get selected against? This is what I answered to above, and not one person answered to what I said outside of calling it crap. The facts are, in groups that can produce far more individuals than they need, differential sexual behaviors often occur, and are selected for. Remember now, “selection” is not really an active event, but a “filter”, as in, if it gets through, over and over again, then it stays. “Selection” is better said to what is removed, as in “selected against”. If a population can create far too many offspring than the population, working within the environmental conditions given, can sustain, then, as mentioned above, traits that allow for a partial decrease in reproductive output, can get through the filter. I gave several examples of this type behavior above in wolves, Naked mole rats, Cattle, etc…
Add to the above the sexual interplay and grooming aspects found in the great apes, and homosexuality as a small part of the total percentage can certainly become a norm.
The above is not a “just so story”, but a basic hypothesis based on observations. If someone cares to test the hypothesis either way, go ahead and do so. A good way to test it would be to find an organism that uses grooming and sexual interactions as a way to solidify a social group, and then see if one can find differing sexual orientations when a larger population is needed, but the given reproductive rate would bring about overpopulation. Remember, the reproduction rate may be selected to say high when and if numbers do drop (bottlenecking events)
Bailey & Pillard, 1991, 1993. A person with a gay identical twin is far more likely to be gay than a person with a gay fraternal twin.
Kallman, 1952 and Heston & Shields, 1968 obtained similar results, although their methodology is more questionable.
Someone’s in denial, or lying, because I distictly recall teaching Lago to like tits.
Good. I always enjoyed those more than oral exams anyway.
Here’s a recent review. Those twin studies are interesting. For a critique of twin studies in general, though, see Lewontin, Rose, and Kamin’s (otherwise infuriating) Not in Our Genes
ROBPLOPROBPLOPROBPLOPROBPLOP
Couldn’t homosexuality just be the extreme (on either end) of the natural variation of sexual desire in order to pair up as many available, fertile mates as possible? It seems that the more variation in sexual desire, the greater chance that even heterosexual, but masculine, women and heterosexual, but feminine, men will pair-bond and reproduce, bettering the chances for the species as a whole.
But I’m just a lawyer, so what the hell do I know.
The most likely explanation for homosexuality is Gregory Cochran’s theory that it’s caused by a pathogen.
ROBPLOPROBPLOPROBPLOPROBPLOP
Scholar
Is that the genetic code for homosexuality?
Animals showing homosexual behavior:
(It’s in Spanish, so someone will have to translate)
“There is only, in my experience, one type of gay guy, as in gay…or not gay. But in females, there seems to be many shades, with 2 general types. Straight women, who are sexually attracted to females for sex alone but desire men for actual relationships, and actual Lesbians who are only attracted to females, and do not care for an emotional relationship with a men ever.
…
Also, it is just cool to watch two chick make-out”
I think your little lesbian fantasy has colored your perception. In your proposed scenario, it appears that you think every woman is really a lesbian deep down. Your options for a woman’s state of being does not allow for women who don’t desire to have sex with other women at all. In my experience, this is not the case.
What IS the case, as others have pointed out, is that there is a STRONG social influence on the expression of attraction. It’s socially acceptable (even encouraged, by guys with fantasies like yours) for women to express attraction for other women (even if she don’t actually want to have sex with them). It is a huge social taboo (encouraged by strict dichotomies like your “all gay or nothing in a man”) for a man to express attraction for another man (even if he doesn’t actually want to have sex with them). So I think expression of attraction and actual desire for intercourse aren’t nearly as correlated as you seem to think.
So please, keep your sexual fantasies out of your science. Not all women want to sleep with other women.
That said, I agree with the other posters who say that sexuality exists on a continuum. It seems to be the best explanation I’ve come across.
And, I’m also pretty disappointed in PZ for supporting such a male-centric explanation for homosexuality. Men didn’t evolve all by themselves, after all. Any explanation that doesn’t account for female homosexuality isn’t good enough in my book.
I live in a gay-friendly neighborhood so I’ve gotten to hear various anecdotes about “how they came to be”.
One (from a man who fit the stereotypically “swishy” personality) said that he was “like that as a child… liked ‘girly’ things, dolls, decorating, was attracted to the same sex, etc.” Another loved to do things like make jewelry but had no sense of wanting to have a career or compete in the job market. Another man said that “he used to date girls until he tried guys… and liked guys better”.
Myself, I’m a straight woman who has been attracted to the opposite sex as far back as I remember, but never played with dolls, likes competing in the job market, and is attracted to “pretty” men (“brawny” men do nothing for me). Then OTOH there are people who have claimed never to have experienced strong sexual/romantic attractions.
All of this leads me to hypothesize that sexual attraction, gender identity /behaviors and sexual orientation are widely varied, with a number of different factors coming into play. Among them:
1. Some people are indeed “hardwired” with regard to sexual orientation. Others lack the “hardwiring”. Like a population of wild animals that gradually lose their fear of humans due to not being hunted, a cultural mandate towards marriage and reproduction could result in any such instinct starting to become less frequent within the population after many generations (because culture, not sex drive, becomes the main driving reproductive force).
2. Hormonal influences on the brain in utero. It’s been shown that higher testosterone levels in the mother affect the developing brains of female fetuses, causing “tomboyish” behavior but not necessarily changing sexual orientation. Levels of hormones may also influence level of sex drive.
3. Nature *and* nurture. Events very early in life may have an effect on individuals predisposed to being more influenced by environment. Could genetics have an influence on that predisposition? Environment and experience may be a cause of lack of sexual feelings.
3. Effects of neoteny (evolutionary trend towards childlike characteristics) and its subsequent entanglement of psychological/emotional behaviors. Observing that some gays seek “lookalike” partners, does this suggests Freud’s hypothesis (of the narcissitic individual) may have been partly true?
Anecdote:
I had a (neutered a bit late at ~one year old) cat that mounted my other cats (a neutered female and an intact male*); presumably to show that he was the household alpha.
*He was intact because I hadn’t yet managed to catch him.
#41:
“Cures” for genetic traits go both ways. There is a good chance the root cause for authoritarian conservatism is genetic. Find the genetic markers for reduced empathy and psychopathology and we’re half way there to wiping out the authoritarian movement for good.
#78: I beg to differ — authoritarian conservatism could be a product of both nature and nurture. The root cause is usually being plain old unappealing in some way, in which case the invididual may turn to authoritarian dogma. Authoritarian dogma is the successful survival strategy of a**holes such as the Taliban and right-wing conservative Bible thumpers. (What better way to get women to breed with them than to tell them that “God” ordered them to “submit”? This also explains the jealousy-fixation they have on Bill Clinton and “Hollywood liberals”)
Of course, the “cure” for authoritarian conservatives is a combination of therapy, anger management classes, going to the gym or even cosmetic surgery.
I like PZ’s explanation. It makes me think of hyenas.
/Of course, the “cure” for authoritarian conservatives is a combination of therapy, anger management classes, going to the gym or even cosmetic surgery./
Are there cures for solipsism? Empathy transplants?
/delurk
It’s quite disconcerting to read all these comments analysing my life as “an interesting scientific question”. If it’s not enough to be reminded so often of my supposed abnormality, being the object of scientific curiousity has a slightly dehumanisisng feel, like being in a sideshow. Not that any of you mean to be rude, of course.
I mean, some of my best friends could be circus performers, but I wouldn’t presume to theorise why they perform in circusy ways before I actually asked a few of them of their opinion.
Indeed, I’m surprised anyone would find homo-, bi-, pansexuality, ect, interesting at all. Bisexuality seems the most natural thing in the world to me. I’m more interested why anyone in the world would want to be straight.
So how about, instead of focussing on what makes the abnormal people different, try to understand why sexuality in general exists, how it has been expressed, how it relates to desire, and the mechanisms of love, pair-bonding, ect.
To Lago @ #12: South Park and porn aren’t great sources for answering biological research questions, and as far as I know, chickens do not make out.
Amazing Kim
Sexuality in any permutation is interesting to the world at large since there are so many social taboos in place. The Madisom Ave mantra is “sex sells!” for a reason . Most people are starved for information. People are confined to a stifled sense of propriety and prudery due to misinformation, disinformation, and cultural bias in the name of moralism. But on a scientific level, knowing how and why is dicey due to all those cultural biases.
Ever try to have a conversation with a doctor(GP) about anything sexual? It’s amazing how many are so obviously uncomfortable with issues even in a clinical setting. How many zoologists/biologists/etc., with a biases against homosexuality, have let their bias taint their observations.
I also assume that you are female. Bisexuality is accepted in females in due course, prurient pipe dreams of men aside. Bisexuality in men was claimed to be non-existant in a recent study that was textbook bad science, however it was published in the NY Times and accepted as factual due to the NYT’s clout. Most people don’t want to there to be any ambiguity in male sexuality for a variety of reasons, which i won’t bother to list. (although I am all male, heh heh)
Without trying to be inflammatory, there is an intrinsic difference between male and female homosexuality in the crudest sense. Historically, any female, reguardless of preference, who is biologically able to concieve could be impregnated since female conception can be accomplished with the female as passive. As horrible as rape/forced sex is, it is common in human history.
The issue is that since men must maintain tumescence in order to accomplish coitus in all it’s phases, can a man, who has no sexual desire for women, accomplish the task? Impotence due to lack of sexual desire would keep purely homosexual males from adding to the population (since the turkey baster is a recent invention, I doubt our ancestors could use artificial insemination as a loophole to the argument). If some “gay” men can “pinch hit”, as it were, would their progeny be more inclined to be homosexual due to inherited paternal chromosonal traits? blah, blah, blah
As uncomfortable as it is, everyone is put under the microscope eventually: those who are obese, under weight, normal weight, diabetics, left handers,right handers, Bipolar, Unipolar, and even those who believe in religions and ghosts. It’s nothing personal toward you. I wish you happiness and I secretly envy that you have doubled your chances for a date on Saturday night.
By and large, this kind of thing doesn’t work evolutionarily, at least for humans. The problem is that for a trait to be subject to positive selection, it must feed back to increase the reproduction of the allele(s) supporting that trait relative to all of the other alleles. So a “responsible” trait that helps everybody equally (e.g. by keeping the population below the carrying capacity of the environment) will lose out to a “selfish” trait that simply reproduces as much as possible. Dominance of the latter trait might result in everybody starving some generations down the line, but natural selection has no foresight, and can’t see that disaster coming. So to make a scheme in which homosexuality gene(s) are sustained by virtue of controlling population, you need to come up with some way in which others who share those genes (and who do reproduce) benefit more from population control than the average individual.
Myself, I’m a straight woman who has been attracted to the opposite sex as far back as I remember, but never played with dolls, likes competing in the job market, and is attracted to “pretty” men (“brawny” men do nothing for me).
Ann Homily
Call me, Ann, and meet your dream guy! I’m svelte, lithe and blithe. For an Alces alces, anyway.
Dial 206-889-4811 and make your wishes come true!
Which is the key question. Since homosexuals propagate less than average then a trait for homosexuality–or even a trait that is merely permissive in that it allows homosexuality to arise as a result of environmental influences–will be strongly selected against, UNLESS there are some nonprocreative benefits of those traits (or the same traits have procreative benefits when present in the opposite sex). So what are those benefits?
The jokester in me wants to give you a great punchline, but I assume you are talking about evolutionary benefits.
If you extract western morality from the process and note Dr. RIchard Burton’s (the explorer not the actor) journals , you will find that many cultures have bonding behaviors that involve sexual play/romance between same sex groups; and that few of them are exclusively homosexual in practice. Exclusive homosexuality in history seems to be rather rare. In fact, the idea of purely hetero/homosexual polarization as a concept is not coined until after the turn of the twentieth century. Our modern culture has defined specific distinctions where there were no clear delineations before.
This may be why there is no single specific gene responsible for hetero OR homosexuality.
Holding Da Vinci, Michaelangelo, Alexander the Great, to modern concepts of “gay” doesn’t hold up even though most of their romantic entanglements were with men.
Again, you can’t define human sexuality in solely procreative terms.
kellbelle1020: Except that it might point to the (reasonable, based on my informal experience) that male and female homosexualities differ, as others have remarked. (I also happen to think there are likely different “sorts” of at least gay men, but that’s not nearly as obvious.)
It is hard to know to what extent this is true and to what extent our culture is simply more open about such things.
If there were a single specific gene responsible, the inheritance would be a lot clearer and we’d probably know what the gene is by now. So presumably, like virtually everything of interest about human behavior, it is the result of complex interactions among multiple genes. But that does not eliminate the evolutionary question of what maintains these alleles in the population.
It is not my perspective, it is the perspective of natural selection, which only sees changes in gene abundance. Of course, an allele does not have to enhance procreation in every individual who carries the allele. It is the total procreation of all of the individuals who share that allele that dictates whether it will increase or decrease in the population over time.
Let me be more concise and we can put this one to bed. Let us take other species that have no formal morality to bias their behavior. Cattle, horses, monkeys, chimps, dolphins, wolves, dogs cats, penguins etc. have been known to involve same sex mountiing and genital play. Some refuse to mate with the opposite sex and adopt same sex mates for extended periods. It is rare for these animals to not mate with the opposite sex eventually barring premature injury or death (or castration). Are these animals different from the rest of there species? Probably not. Is their behavior within the context of normal? Probably.
But if there were specific individuals that were overtly feminized males or masculinaized females who preferred only same-sex mates and refused opposite sex mates, barring genital ambiguity, then genetic differences should eventually be determined; but this would probably be much rarer as to be statistically insignificant.
You would probably find no differnce in animals identified as heterosexual or casually homosexual in behavior, therefore searching for “gay” alleles would be like the proverbial needle in a haystack. Natural selection seems to favor dopamine producing persuits. Dominance in mounting determines hierarchy, and play strengthens group ties.
The ancient greeks held sexual duality as a normal and moral practice as many other cultures have. Judeo/Christian societies declared all same sex practice to be anathema. Hindu culture once embraced it but western influence has changed this. Muslim religion publicly forbids it yet “bisexuality” was historically common yet closeted in the Mideastand. Cultural bias and homophobia, in the strictest sense, will cloud that definition of homosexuality and whether or not the trait is a genetic anomalie.
Thanks for your thoughtful reply, Jsn.
I do agree with your point that every conceivable human trait is fair game for research – my my point was that there are too many instances where the group being studied (women, people of colour) are infantilised and their own experiences are dismissed in favour of the ‘objective’ pov.
Just on a side note, the Saturday night equation goes something like this:
Available people to date = (Gentlemen + Ladies) – Straight women – Gay men – People who are already in relationships, except for those who want a generic bisexual lady with which to experiment (that gets a bit annoying) – People who think bisexual is another word for (promiscuous, a phase, bragging rights, teh generic hawt, threesomes with ex-girlfriends) – Lesbians who see bisexuals as traitors – People I don’t like – People who live in other countries.
So I figure, it’s probably about one extra person. Now you can see why I comment on Pharyngula on Saturday nights!
Hrm.
David Marjanović mentioned (indirectly) the Italian research.
That’s this paper: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1691850
The research concludes that some male homosexuality is conserved through maternal lines because it is associated with increased female fecundity.
I personally think that we will eventually conclude that homosexuality has multiple causes of variable heritability, some of which may be adaptive.
Homosexuality seems to be about psyhcic androgyny as well. And that kind of androgyny seems a reguirement for rebirtth and divinization.
http://www.world-mysteries.com/PhilipGardiner/index.htm
And that kind of androgyny seems a reguirement for rebirtth and divinization.
*giggle/snort*
That’s funny.