Friendship, a sense of community, love, physical attraction, etc. All emotions that to some extent seem to overlap.
Personally I find it remarkable that amost all of us end up attracted to only one sex, than that a few are attracted to their own. As has been expressed by other posters, homosexuality doesn’t have to be a trait that’s been selected for by evolution, it could simply be a side effect.
Quite so. Although much of sexual orientation may be innate, in the sense of being present from birth, not all of it is genetic. Some of the predisposition can be developmental.
However, the evidence is that sexual orientation is to some degree genetic. Beyond what uglybeech has said about this, this does not necessarily mean there is a single gene for homosexuality, but that several different alleles of different genes may produce it. If these alleles are advantageous when found singly, they will persist in the population, and produce homosexuality when by chance they come together, even if there is a selective disadvantage to homosexuality itself.
The persistence of the trait of exclusive homosexuality in the population at fairly high rates for a trait that frequently produces behavioral sterility is to some degree a puzzle. But no one ever seems to ask this question about other traits that produce behavioral sterility, such as the degree of religious commitment that causes one to join a celibate order, or the degree of nerdiness that causes one to never ever get a date. There may be a question as to how innate these are, but I suspect they may be as heritable as exclusive homosexuality is. And I suspect that at least the latter condition has a higher frequency in the population.
Does the primary factor have to be genetic? In the highly complex series of hormone-driven events that determine a fetus’s sexuality during gestation, I can easily imagine tiny and random variations that have dramatic results.
Rather like left-handedness, it represents a minority but not inherently harmful variation.
There is evidence that birth order and sibling sex ratio may be linked to homosexuality, implying that some maternal hormonal mechanism may be at work.
Studies such as this one suggest that there is at least some genetic component to male homosexuality, but how strong it is is open to question.
From the conclusions:
Given that exclusive homosexuality produces behavioral sterility, in evolutionary terms it’s highly harmful, much more so than being left-handed.
I am quite curious about what is going on with the people who ask this question. I am merely seeking information from the OP and am not trying be judgemental. (Note that these questions address issues already raised in this thread.)
Questions to Voluble:
Are you aware that almost all member of social insect colonies never reproduce? If so, does this in any way puzzle you?
Are you aware that homosexuals regularly reproduce? I.e., that are not inherently unable to have children.
(Please be aware that the above is a question to the OP and the OP only.)
I repeat, I am merely want my curiousity satisfied.
Insects aren’t a very good analogy to human sexual behavior. Take honeybees: the queen mates with 10-15 drones per day, and on a good day can lay 2,000 eggs.
I’m answering it because I think your own questions show some misunderstanding of the issues.
This is one of the most interesting questions in evolutionary biology, and in fact it was a longstanding puzzle. The answer is that in general it is due to kin-selection, and is so prevelant in insects in part because of the peculiar genetics of the Hymenoptera (ants, bees, and wasps). Although kin-selection has been invoked to describe the persistence of homosexuality in human populations (as has been suggested in some of the posts above), the situation in insects is largely irrelevant to that in humans because of differing genetics and population structure.
This is irrelevant from an evolutionary point of view, as long as homosexuals have a lowered reproductive rate compared to heterosexuals. This is almost certainly true.
Not quite. The allele resides on the X chromosome, so women have to get two copies of that allele to express the trait while men need only one (the Y chromosome doesn’t have a “corrective” counterpart). But a female who exhibits the traits must have a father who also exhibits the trait (and a mother who is at least a carrier). Also, note that male hemophilics’ sisters only have a 50/50 chance of being carriers (unless their mothers were hemophiliacs, too).
This, while speculative, is a really good point, and one that I’ve always thought migh be the answer. It might well be that our species evloved to have tighter male-male bonds than our ancestors, and that caused a spill over effect into some small amount of homosexuality. That may also be true of female-female bonds. If you look at our closest relatives (chimps and bonobos), humans have much less intra-group conflict. In fact, given our ability to make weapons, it’s amazing that the murder rate isn’t sky high.
Frankly, I think this is a better possible explanation than the “babysitter hypothesis”. I’m not aware of male babysitting being significant in any human society, and the non-human models (wolves, etc.) don’t include instances of male-male sexual attraction (the non-alpha wolves don’t form same sex pair bonds, even if they don’t breed as often as the alphas do).
Who knows… there may even be a tie-in to the sterotype that homosexuals are more artistic, and it certainly seems that art played a crucial role in the evolution of our species. In short, the possibilities are endless and focussing exclusively on the alleged reduced reproductive success is missing the point.
As might be expected, I’m going to praise my cousin beech’s response as the best I’ve seen.
But as a detour, responding to
With all due respect, E.O. Wilson now says, and I agree, that kin-selection is a poor explanation of social colonies, which are found in not only in hymenoptera (which have the peculiar genetics), but also in termites, beetles, shrimp, and naked mole rats (all of which have ‘normal’ genetics). Wilson article at FindArticles.com | CBSi
Very interesting. Thanks for that, I hadn’t seen it yet
However, my more general point that insect societies are poor analogues for understanding homosexuality or other kinds of behavioral sterility in humans still stands, whether or not the evolution of sterile castes is due to haplodiploidy and kin-selection, or alternatively to coloniality, as Wilson says.
This is incorrect. Bonobos have almost no conflict. Instead of getting angry and fighting, they have sex. What’s more, male-male bonding behaviors (mostly grooming) are more pronounced in groups where there is conflict between the males than in groups within. Male-male grooming is more common in chimps where there is a lot of male conflict while female-female grooming is more common in bonobos where there is little to no conflict.
A trait does not have to be expressed solely in one gene to be genetic. The rates in male homosexuality are similar to those in schizophrenia which is polygenetic. What’s more, there have been many studies which have shown that genetics are switched on and off by the uteral environment. Mice can be made to be more outgoing or timid depending what uterus they develop in. There is some evidence that suggests that homosexuality is more common in times of stress for the mother. Often stress is caused by famine or other hardships where it would be advantageous to limit population size. Many species produce less offspring than normal when stressed and a non-breeding member of the population could help.
Futhermore, if homosexuality was controlled by one gene, the heterozygous condition could be beneficial to the species. Jared Diamon suspects the reason why Tay-Sachs is so prevailant amoung Ashkenazi Jews is because the heterozygous condition helped prevent those individuals from getting TB.
Also, homosexuality is not new to our species and there have not always been taboos against it. The taboos are rather new, on the scale of things.
Personally I think there may be multiple causes of and multiple types of homosexuality. For example, I think that what causes a particularly effeminate gay man (not referring to one who has the wrong “plumbing” and chromosomes, but a man who happens to be effeminate) could well be different that what causes a “butch” gay man (the Richard the Lionheart//Brokeback Mountain type who would never miss a chance to go hunting by staying in the cave and who is the most likely to be closeted) could well be different that what causes a lipstick lesbian could well be different from what causes a butch lesbian, etc… Some forms of homosexuality could well be exclusively genetic and others more influenced by events, and female sexuality on the whole seems a lot more fluid than male (for every bisexual man I’ve known [i.e. had concurrent sexual desires for both men and women] I’ve known several women who so identified, and that seems true of most of the other people I know who’ve explored the matter.)
All we really know with some real certainty is that with a teeny tiny insignificant minority of exceptions gay men and lesbians (i.e. those whose sexual attractions are overwhelmingly to exclusively same sex oriented) do not consciously choose to be so and that they cannot change (or most of us would in adolescence). I think the same percentage would tell you that from the time we had a notion of what sexual attraction was (or even before) we knew it was towards our own gender. On the subject of twins, it’s true that different studies show that the identical twin siblings of gay men/women are often not gay, but for identical twins it is a notably higher percentage than fraternal twins. It’s also true that in sets of identical twins in which one is left handed, the other is very often (25% to 50% depending on the study) right handed (and as with gays there is much debate as to whether genetics plays a role). Who knows?
Ultimately I agree with a song I once heard Topol sing while standing in the Israeli desert on a bad cable documentary:
Some people say a part of the sun
fell off into space and the world was begun
others have argued much different ideas
I really don’t care just as long as we’re here
and we’re queer. Unless you’re not.
No, it was correct. Bonobos have much less intra-groop conflict (fighting) than chimps, and they do use sex in many situations to ease conflicts, but they still “go at each other” more than humans do. One key difference between bonobos and chimps is that you’re likely to see females ganging up on males.
Humans excel at inter-group conflicts, but the amazing thing about us, as a species, is how infrequent intra-group confilcts are. When was the last time a fist fight broke out at your place of business? Go watch a group of bonodos for a few days and you’ll see plenty of skirmishes.
ps- I want to term a new discussion law. It’s like Godwin’s Law but concerns animal sexuality and has two variants:
1- As rational discussion about human homosexuality progresses, the chance of sexual behavior of bonobos being mentioned approaches 1.
2- As heated discussion about human homosexuality progresses, the chance of sex with livestock being mentioned approaches 1.
Look through the history of these threads and you’ll rarely find a thread of more than 20 posts that doesn’t comply. 
You forgot polygamy. 
But #1 is just the nature of the beast (pardon the pun). Chimps and bonobos are our closest relatives and their different sexual practices are relavent to understanding our own.
Hee hee. But will we call it Sampiro’s Law or Briston’s Law?
As for women, wasn’t there a study a while back that proposed that lesbians tend to have longer ring fingers than the average woman because of higher testosterone levels in the womb? Has there been any conclusive evidence either way?
That report turned out to be generated by a lesbian sociobiologist who wanted to combine her search for a partner with really big fists with her quest for tenure. Many people no longer give it credence any more than they do John Paulk’s article "Closeted Gay Men Who Meet For Anonymous Sex More Likely to Find Satisfaction at the Airport Holiday Inn Room 122 on Wednesday Night if they Knock Twice and Say ‘I’m a Friend of Buddy’s’ " report in “Ex-Gay Issues and Decorating Tips Quarterly”.
Do you have a cite for this? Yes, bonobos and chimps will engage in rough behaviors, but as primatologist Frans de Waal noted, so do little boys at play. While I have not had the chance to observe bonobos for more than an hour at a time, I have not noticed any aggression during the times I have observed them.
Oddly enough, I remember reading about it in Frans de Waal’s latest book Our Inner Ape. But if we’re going to include juveniles, then I’d be surprised if young bonobos don’t tussle with each other at least as much as young humans do.
Bonobs are extremely peaceful compared to chimpanzees. But only humans can maintain a relatively peaceful social group in places like crowded bars, sporting events, or even simply tribal life. Imagine locking 50 bonobos in a room the size your local pub. They wouldn’t be able to handle it. Yes, that’s an artificial environment, but it’s a good demonstration of why we’ve been able to be as successful a species as we have been-- we have almost unbelievablly low incident rate of intra-group physical conflicts. If we didn’t, we’d never be able to advance beyond small bands of hunter-gatherers.
Colibri. You have not just baffled me, you have double baffled me!
Are you feeling alright? Are you trying to whoosh me? What is going on there?
The questions were directed to the OP and the OP only. Period. No one else. I was only asking about what background knowledge and understanding the OP has. I have zero interest in your background knowledge and understanding.
Then you don’t even answer the questions I posed!!! Wow. Not only not in the same ballpark, not even on the same planet. I’ve had my posts misunderstood before, but this is the grand champion.