Seeing as it is so widespread in the animal kingdom, I would imagine homosexuality has some purpose that is not immediately obvious. If anything, isn’t it an obstacle to the perpetuation of a species, pretty much the main point of sexuality? Can anyone shed some light on this?
It’s only an obstacle if they are exclusively homosexual.
It probably doesn’t have a point, it’s just that no matter how widespread it may be, there’s plenty of heterosexuals (and homosexuals) mating that it’s not getting bred out.
Also, as far as I know, it’s not hereditary. A long lineage of heterosexuals doesn’t mean their offspring will be one.
Aren’t there some type of animals ( I think lions are like this) where the dominanat male takes over a pride and he breeds. No one else can breed, but the other males hang around and challenge him from time to time. Eventually he’ll be overthrown, but all these heterosexual lions are not breeding either.
What’s the purpose of sterility?
Just because it’s possible doesn’t mean it has a “purpose” We can also blow bubbles in chewing gum or soap – but blowing bubbles is not the “purpose” of our mouths, lips, or lungs; it’s just something cool we happen to able to do with some parts of our anatomy that were adapted for breathing and eating.
Being sexually attracted to other people does help the perpetuation of the species, as long as enough of it is to the opposite sex. So, does it matter if some of this sexual attraction is directed in ways where fertilization in unlikely or impossible to happen?
There are many papers written about this subject I’d be willing to bet at least a few books as well.
Clearly homosexuality is not a sufficient to destroy a species. It can be recorded in all types of mammals including humans, who continue to reproduce just fine.
One line of thought is it has no purpose whatsoever. It simply isn’t detrimental or beneficial enough to the species, so it never evolves out or becomes more common.
Another argument is it allows herd or pack animals to have more male chaperons to protect the young without creating an overly competitive mating environment.
There is no factual answer to this question. BTW, this has been done about 18,000 times on this MB. If you search, you’ll find at least 17,999 of those threads.
Can someone tell me about homosexuality in ancient Greece. I am not a historian, but I believe that homosexuality was an accepted practice, between older men and younger boys anyway. Did those boys end up living mainly heterosexual lives when they matured? It seems that what was accepted was older, perhaps wealthy or powerful men, and young boys. Was adult to adult homosexual behavior accepted during those times? Did homosexual women have similar societal acceptance?
Yes but it doesn’t stop up from procreating.
No available factual answer, yet. But I’m sure one exists. We aren’t talking about some fundamentally random, causeless quantum event after all; nor are we talking about some unique historical event for which the data to unravel it may simply no longer exist. We are talking about something widespread enough through space and time to affect many different species, and we have no reason to assume its stopped. Whatever pressure creates so much homosexuality should be possible to identify and verify, we apparently just haven’t done it yet.
First of all, most things in life have no evolutionary purpose. They just are. Why are some people left-handed? Why do people have different eye color? There are differences that exist for no practical purpose whatsoever.
And as far a perpetuating the species is concerned . . . I don’t think there’s much danger of our species dying out because we’re not reproducing fast enough. So the “biological purpose of homosexuality” might be to keep the population explosion manageable.
If a person has a single copy of the sickle-cell anemia gene, they gain a strong resistance to malaria, which strongly increases their ability to reproduce in areas where malaria is endemic. A population with the sickle-cell anemia gene has its reproductive success increased in such areas, but with a cost of some members having a decreased lifespan due to having two copies of the gene.
One conjecture about homosexuality is that it could in part be a side-effect of some other process that increased the general population’s reproductive success even with the expected decline of reproductive success for homosexual individuals within that population.
Not all women have taste in dressing and hairstyles and makeup and decor necessary to attract a mate. And other women are not really out to help them if it removes their desired type of mate from the dating pool. Gay men fill in this gap because these tasteless woman really can trust the gay men to give good advice on these topics. A gay man can make a woman’s lack of taste a non-issue for a troglodyte straight man who cares about such things.
Which is all that matters in the context of a posting in this forum.
Whatever pressure creates so much homosexuality should be possible to identify and verify, we apparently just haven’t done it yet.
There needn’t have been any “pressure”, or a single cause for that matter.

Was adult to adult homosexual behavior accepted during those times? Did homosexual women have similar societal acceptance?
No, and probably not, but we don’t know much about the social lives of women in ancient Greece, because the ancient Greeks didn’t really consider the lives of women to be worth discussing.
From the Economist 10/23/2008, the concept is that gay genes but not gay (not enough genes or not another environmental factor) makes for more partners and thus more reproductive fitness:
THE evidence suggests that homosexual behaviour is partly genetic. Studies of identical twins, for example, show that if one of a pair (regardless of sex) is homosexual, the other has a 50% chance of being so, too. That observation, though, raises a worrying evolutionary question: how could a trait so at odds with reproductive success survive the ruthless imperatives of natural selection?
Various answers have been suggested. However, they all boil down to the idea that the relatives of those who are gay gain some advantage that allows genes predisposing people to homosexual behaviour to be passed on collaterally. …
… since there is evidence that male homosexuals, at least, are more likely than average to come from large families, is that the genes for gayness bring reproductive advantage to those who have them but are not actually gay themselves. Originally, the thought was that whichever genes make men gay might make women more fecund, and possibly vice versa.
Brendan Zietsch of the Queensland Institute of Medical Research in Brisbane, Australia, and his colleagues have, however, come up with a twist on this idea. In a paper to be published soon in Evolution and Human Behavior, they suggest the advantage accrues not to relatives of the opposite sex, but to those of the same one. They think that genes which cause men to be more feminine in appearance, outlook and behaviour and those that make women more masculine in those attributes, confer reproductive advantages as long as they do not push the individual possessing them all the way to homosexuality. …
… There are also data which suggest that having a more feminine personality might indeed give a heterosexual male an advantage. Though women prefer traditionally macho men at the time in their menstrual cycles when they are most fertile, at other times they are more attracted to those with feminine traits such as tenderness, considerateness and kindness, as well as those with feminised faces. The explanation usually advanced for this is that macho men will provide the sperm needed to make sexy sons, but the more feminised phenotype makes a better carer and provider—in other words an ideal husband. And, despite all the adultery and cuckoldry that goes on in the world, it is the husband who fathers most of the children. …
… Dr Zietsch and his colleagues tested their idea by doing a twin study of their own. They asked 4,904 individual twins, not all of them identical, to fill out anonymous questionnaires about their sexual orientation, their gender self-identification and the number of opposite-sex partners they had had during the course of their lives. (They used this figure as a proxy for reproductive fitness, since modern birth-control techniques mask actual reproductive fitness.) … the team was able to show that both atypical gender identity and its influence on the number of people of the opposite sex an individual claimed to have seduced were under a significant amount of genetic control. More directly, the study showed that heterosexuals with a homosexual twin tend to have more sexual partners than heterosexuals with a heterosexual twin.
According to the final crunching of the numbers, genes explain 27% of an individual’s gender identity and 59% of the variation in the number of sexual partners that people have. The team also measured the genetic component of sexual orientation and came up with a figure of 47%—more or less the same, therefore, as that from previous studies. The idea that it is having fecund relatives that sustains homosexuality thus looks quite plausible.
FWIW. I’d link but it’s behind a firewall.
Population control is a possible answer. At least in mice.
When you keep mice in a cage, limiting their room, but giving them unlimited food and water, they start to do things like kill their young, fight among themselves, have homosexual sex, and so forth. Of course- that’s MICE and not humans, but the experiment is a classic, and I did it in college myself.

From the Economist 10/23/2008, the concept is that gay genes but not gay (not enough genes or not another environmental factor) makes for more partners and thus more reproductive fitness:
It doesn’t have to even be genetic. It could be a glitch in hormone secretions during the developmental process in the womb. A certain subset of the population becoming attracted to their own sex may just be one of those things that happens when you try to put together an animal body.