I haven’t taken biology yet, but from my understanding things mutate randomly and if they are a good mutation stay and if they are a bad mutation they go away. Good and bad meaning as in keeping the species alive. So is it possbile that homosexuality is a random mutation causing animals of the same sex to like each other more then the opposite sex? Of course it wont get passed on because you cant have kids with someone who is your sex, but maybe it just happens commonly. This is just something I think about when I can’t get to sleep.
I dont want to talk about morals or have this sent to the pit or great debates if it does not have to. Just want to know if I’m on the right track.
There is evidence that suggests that homosexuality could have genetic component:
in 52% of cases where one identical twin is homosexual, the other is, as well;
in 38% of cases where one fraternal twin is homosexual, the other is, as well.
The idea suggested by those figures is that the closer the genetic bond, the higher the probability of the same sexual orientation. That hardly makes it a cut-and-dried case, however.
The evolutionary suggestion that has been put forth is that a homosexual (who does not normally reproduce) is able to provide more nutrition to the family/clan without further draining the resources by producing children that would drain those resources. Since his/her nieces and nephews carry on a certain percentage of his/her genetic code, s/he is actually promoting genetic survival. There are several species of animals which have “bachelor uncle” individuals, so the concept is not far-fetched on the face of it.
It is way too early to guess whether there is any truth to the speculation.
In my evolutionary biology course in college, I remember discussing why homosexuality evolved at one point as a class topic. Apparently chimps can be homosexual too, and I believe some other lower species, though I would be at a loss to tell you which.
[note: like the OP, I fear the Pit, and I note these were what was suggested and I am NOT claiming they are right or wrong, just that they were presented to us]
One of the theories at that time was that it was a sort of throwback to those species that change sex later in life (such as certain fish like sheepheads and wrasse) and that there might be a type of ‘confusion’ as to what sex they are at that time vs. how they are behaving. This might also explain my in many homosexual relationships, you often see one member acting more effeminate and one acting more masculine.
Another was that it was a societial necessity thing to establish boundaries, and even a pecking order in some species. This might explain otherwise heterosexual men turning homosexual in prison to establish power by forcing sex on those weaker than them.
Finally, there is was an idea that perhaps homosexuality reinforced so-called ‘good’ genes and ‘good’ behavior. That is, two animals of the same sex left to themselves might practice reproduction on each other so that when with a mate of the opposite sex at a later point, the act would be done correctly and result in successful reproduction. Of course, that’s really an argument for bi-sexuals, but whatever.
Anyway, nothing much came out of the discussions, though it was an interesting side topic at the time…
I think that it is entirely possible that in a highly sexed species like humans, with their intense and childlike curiosity, the tendency toward homosexuality is just one more potential behavior pattern existing in all of us to one degree or another. Chemical, cultural & experiential (is that a word?) variations will repress or encourage it. When you look at cultures that do not have a taboo, or that actively encourage homosexual behavior (the Spartans come immediately to mind), there seems to be a lot of it just occurring naturally. More teenagers have same-sex urges at one time or another. Perhaps if western culture ever relaxes it’s dark-age grip on so-called “family values”, we’ll see a lot more bisexual behavior and a lot fewer deeply screwed-up teenagers.
If, over time, only 3% to 5% +/- of a given population is
indicating same sex orientation (IIRC current best estimates of human same sex orintation percentage) this will have a negligible effect on the survival of the species.
The biological system of inter-related switches that control sexual preference and make an animal (man included) have the tendency to become same sex oriented are probably both genetically and environmentally (neo-natal fetal development environment) mediated and it would be hard to imagine they do not respond at some level to environmental stressors.
As a WAG at a basic level positive effects could be less competition for females in an over populated, low resource environment where males compete and potentially damage each other for females. Same sex orientation in this scenario would be good for the related genetic group and would also potentially enhance the same sex animal’s chances of survival.
From a female perspective the “selfish gene” advantages of same sex orientation are less clear … might be avoidance of childbirth dangers but hard to imagine that this was a choice for women in the pre-historic environment that crafted the current homo-sapien brain. Perhaps population and resource stressors simply increase the tendency to have switches flipped to same sex orientation for both sexes and percentage affected is small enough not to have negative repercussions. Perhaps same sex females were impregnated and had children and same sex tendencies were manifested as
bonding very strongly to other females in related family groups and being extra tough/dominant, neither one of which would necessarily be a negative survival characteristic for the related genetic group.
Would be interesting to see a study on same sex tendencies in high stress (ie high population/low resource) environments and see whether there is a correlation or if it’s really just a throw the genetic/environmental dice and is wired into being a two sex species.
Pre-civilization (and even afterwards), you lost a percentage of women to death in childbirth. This would tend to cause a shortage of females. A male homosexual pair would reduce competition for women within the tribe, making it more likely that the tribe survived. Remember, it’s not always survival of the individual’s genes; group survival is also a factor (since if the group dies out, the individuals do, too).
This doesn’t acount for lesbianism, but it may just be that the gene for attraction to the same sex (if it exists) is not sex linked and can affect women, too.
BTW, the idea that homosexuals don’t pass on their genes assumes are very narrow on/off dichotomy between homosexuality and heterosexuality. Sexuality works on a continuum and there are plenty of times when a homosexual has had sex with someone of the opposite sex.
I read “somewhere” that the part of the genome they suspected of including the gay gene had a tendency to mutate very rapidly, so even if one strain of homosexuality got bred out, another one would emerge very rapidly to take its place.
OK, all the ideas about homosexuality being good for the species are just wrong. It doesn’t matter if it would be good for the species if some people were homosexual, the homosexual individual would have to benefit from being homosexual.
The other thing is that homosexuality is not as deleterious as one might think. Do you think homosexuals never have kids? No, they often have kids, and probably had even more back when homosexuality was unnacceptable.
I am certain that there is no “Gay Gene”. It wouldn’t make sense. My feeling is that humans have a strong instinct to have sex, and we have no obvious signals when in estrous. Sex was co-opted long ago for other purposes…social bonding, fun, etc. So we have humans who wanna have sex all the time, there are no clear signals as to when or what to have sex with, so you get humans doing things that cannot result in pregnancy.
Remember that it is not same-sex contact that would decrease the number of offspring you might have, it is refraining from opposite-sex contact. Having sex with other men is fine, as long as you don’t stop having sex with women. So the consequences of making a false-positive error…that is, having sex with a same-sex partner…are minimal, but the consequences of making a false-negative error…that is, not having sex with a fertile partner…are large. So you have selection to have sex with anything that moves, as our brains get larger and larger you get these new behavior patterns possible.
But homosexuality is not caused by a single gene, or even many genes, so the theory that it should be bred out of existance doesn’t work anyway.
The theories about a genetic benefit to homosexuality generally seem to be based on the principle of kin selection. The idea is that people with “gay genes” (which you’re probably right is a huge oversimplification) don’t have children of their own (again, another oversimplification), but they somehow benefit the rest of the extended family which makes up their happy little band of hominids–maybe by acting as an extra adult caregiver who never has kids of his/her own to worry about. Since these kids are their nieces and nephews, and therefore have many genes in common with their lesbian auntie, she’s still looking after her own genetic investment, even if she’s not cranking out little offspring by herself. I don’t know if this hypothesis is actually correct or not, but there is a way to make it work within the context of evolution by natural selection.
I don’t think anyone said it was “good” for anything, though that was being explored. That said, if you are just worrying about something being good, you are missing the point of genetics.
**
Really, doctor? Please do show me the research you have done to be “certain” of something that is still hotly debated in the scientific community.
The “hypothesis” you then posit, I must say, is kind of silly too. You seem to be using the old “fucking feels good so people fuck” line. I think that if this were the case, homosexuality would be quite prevalent, unless you wish to assume that heterosexuals don’t enjoy sex as much as homosexuals.
In this thread, nobody seems to have a solid grasp on what mutations and genetiics are really about. It isn’t as simple as “good mutations survive, bad mutations die.”
There are mutations which are patently bad - cancer, for example - which are with us and have not gone away.
There are mutations which are neither good or bad which still happen. Left-handedness. Is there an advantage to this? A disadvantage (and no, I don’t call no left-handed scissors a thgreat to life here)? Not really. But it happens.
There are mutations which are both good AND bad. Sickle Cell is common in Africa, because it is helpful in dealing with malaria, which is common there. Here in the US and in other places where malaria is not a problem, sickle cell is not desirable.
There are mutations which are good - wings to fly would be nice - which have not happened yet and probablty never will.
Ultimately, while nothing is certain yet (contrary to what Lemur866 said), evidence in several studies shows that there is a probably genetic link of some sort, and it might be so complex (way beyond just finding a “gay gene”) that we might reach a point where overwhelming evidence that sexual orientation is genetic for the most part is there, but finding exactly where and why is not known for much longer.
Yer pal,
Satan
[sub]TIME ELAPSED SINCE I QUIT SMOKING:
Four months, two weeks, three days, 50 minutes and 20 seconds.
5561 cigarettes not smoked, saving $695.17.
Extra time with Drain Bead: 2 weeks, 5 days, 7 hours, 25 minutes.[/sub]
"Satan is not an unattractive person."-Drain Bead
[sub]Thanks for the ringing endorsement, honey!*[/sub]
Well at least everybody else was humble enough to say
“WAG-speculation-possible-theory” but you are apparently
sure enough of your opinion that you feel no need for any such qualification of your “feeling”.
IIRC I believe that separated twin studies have established that there is a statistically significant heritable component to same sex preference. The unknown is the overall degree of influence of this component and how it manifests itself biologically, not that it exists.
I’m not up on this topic as much as I would like to be, but I’ll throw in my two centimes anyway.
While some evidence suggests that homosexual behavior may have a heritable component, (BTW, could we get a cite for those percentages, tomndebb?) no gene or complex of genes has yet been discovered that explains it. It is also impossible at this time to rule out a genetic component (unless you know something I don’t, Lemur… please share it if you do ).
Only purely homosexual behavior can be said to eliminate the chance of passing on the heritable component of the behavior. Homosexual behavior that is not exclusive of heterosexual behavior allows the heritable component to be passed on. How many people engage in heterosexual behavior before or after homosexual behavior or engage in bisexual behavior? I don’t know the answer, but I’m willing to bet that it’s not an insignificant number. Kudos to all the posters who brought this up before me and made better points about it than I could have.
I think Yarster and Lemur made excellent points about homosexual behavior being coopted for use in social interactions and as “practice” behavior. I think someone mentioned the chimps, and dolphins are also known for “homoerotic play” (don’t have a cite with me, but I’ll provide it if asked). I’ve heard it suggested that this serves the same sort of function that play fighting/leaping/catching/problem-solving does in the cubs of various carnivores. I don’t know if there are any empirical studies that establish whether this hypothesis is accurate or not, but I imagine they’d be difficult to perform anyway.
Finally, homosexual behavior doesn’t preclude indirect fitness benefits. For example, a non-breeding ant helps pass on common genes by helping raise its sister’s offspring. Tomndebb covered this well.
I think we really should look upon this as a behavior not set in stone at birth. I would be very surprised if environmental factors played no role in expressing these behaviors. That still doesn’t mean it can’t have some heritable component, tho.
Here is a site that mentions the Bailey and Pillard twins study. Interestingly, it is a site that is critical of twins studies, in general. Nature’s Imperfect Experiment
I got the fraternal twin figure wrong–it was 22% not 38%, and non-twin homosexual brothers run at 9%–but I don’t figure I did too badly since I hadn’t seen the study since the month after it came out in 1991.
…and of course, the vast majority of mutations are neither good nor bad, but relatively neutral. This is not an insignificant point.
It is often questionable to start with the assumption that if the mutation persists, it must be being actively selected for. One can only be certain that it is not being selected against. It is much better to start from environmental factors and then examine how populations are affected.
IOW, who said there needed to be a benefit to homosexuality?
It is also possible that there are other traits non-related to homosexuality that are colocated genetically, and which are useful. Since homosexuality, from a species-wide perspective, is a relatively neutral mutation, it might actually be considered a “side-effect” of something else that IS being selected for…
Are you sure that you have a solid grasp here? To the survival of the species in the old days, cancer was a beneficial mutation. After you have reproduced all that you are going to reproduce, your only function is to raise children and provide for them. Once your drain on resources is more than your contribution, the family or society is better off with you gone. So after a certain age, you are likely to get cancer and die, which is good for the group. Sorry, but evolution is a harsh mistress.
Of course nowadays, cancer is a bad mutation because we care about our elders more than just their ability to provide food. They can now provide us with wisdom and guidance and hold a family together. This wasn’t so important when our species just worried about where to find it’s next meal.
Good mutations nowadays wouldn’t go very far. After all, everyone around gets a chance to reproduce. Unless your mutation is the ability to have vast amounts of children, your mutation won’t gain much acceptance, since everyone else is having children too. And even that mutation wouldn’t be so beneficial in today’s society, where those with a choice are preferring to have less children.
So I’m afraid it is as simple as good mutations survive and bad ones vanish. You just have to think of “good” and “bad” on the right terms.
I doubt that cancer is needed to kill off the aged. In fact, cancer has only become a statistically significant killer in the last 150 years as other diseases have been conquered so that we live long enough to succumb to cancer.
I see no evolutionary benefit to humanity brought by cancer. Some things just break.
I strongly believe that there is a genetic component to homosexuality. The paternal cousin in my family that I most resemble in terms of looks and personality is also a lesbian. As is the maternal one.
And then there was the time I dated a second generation lesbian…
Based on casual observance, I’ve known a lot of gay people to claim that they have other gay relatives.
That is patently wrong. The vast majority of mutations are relatively neutral. That’s called “genetic diversity”. Are you really gonna tell me that because more people have brown eyes than green eyes, that brown eyes offer a survival advantage? Eye color evolves as a survival-neutral trait.
If you’d like I can suggest half a dozen books which you might read to get a better grasp of this.
We are also by far the most intelectually advanced species to date. Meaning we don’t go completely by instinct. If an animal operates completely on instinct, and it has a completely homsexual instinct then it will not procreate, and not spread homosexual genes. If it is a mutation that occurs once every 1000 births then it would remain about the same throughout evolution. A person however can compete against instinct. If I was a gay dude living in a 16th century country where they burned homosexuals at the stake, I would find a chick and think about what ever I had to think about to have sex with her and make babies, and therefore pass genes that would not have been passed in a pure instinctual species. Therefore our logic may have allowed us to increase the genetic homosexual tendancy of our species to a density that wouldn’t occur in the “natural world”. This is a theory I made up in the last ten minutes, so it may have many flaws But theoretically it could explain why homesexuality hasn’t been selected into near nonexistance in our species, if it has a genetic component at all.
