Author Topic: homosexuality and evolution  (Read 420 times)

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Online Mrjason

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homosexuality and evolution
« on: February 21, 2014, 08:16:03 AM »
Just read this article - http://www.bbc.co.uk/news/magazine-26089486, its not really saying anything that hasn't been discussed here before but does give a condensed version of ideas spread over several threads here.

I did find this part particularly interesting though

Quote
Qazi Rahman says that alleles coding for same sex attraction only explain some of the variety in human sexuality. Other, naturally varying biological factors come into play, with about one in seven gay men, he says, owing their sexuality to the "big brother effect".

This has nothing to do with George Orwell, but describes the observation that boys with older brothers are significantly more likely to become gay - with every older brother the chance of homosexuality increases by about a third. No-one knows why this is, but one theory is that with each male pregnancy, a woman's body forms an immune reaction to proteins that have a role in the development of the male brain. Since this only comes into play after several siblings have been born - most of whom are heterosexual and go on to have children - this pre-natal quirk hasn't been selected away by evolution.

This idea is new to me.
A pretty good biological rebuttal of the old "well, how can they pass on the gay gene" chestnut.

Offline Chronos

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Re: homosexuality and evolution
« Reply #1 on: March 16, 2014, 07:32:59 AM »
One of our original forum members, DaveDave (now banned), apparently does work in genetics or genetic research. I think he worked for a university, but I'm not sure.

Anyway, I think it would be safe to describe DaveDave as homophobic. He provided detailed explanations of how homosexuality could not be genetic. Maybe he was right, but we still have a lot to learn about genes. I sometimes think his predilection against homosexuality made him find answers he liked. All we know is that our sexual orientation or preferences are innate, not chosen. I have nothing to use but genetics as the cause. Does one like the color blue because of genetics or personal preference? I think a lot of things we do are caused by genetics. If we can become ill from our genetics, why can't our minds work based on our genetics?


That issue of the younger male children more frequently being gay than the older male children certainly does have a correlation to our observations. But the explanation provided is not a causation. I know at least 3 families where the eldest sibling (a son) is gay, but all of the younger children are straight.

Obviously, our understanding of these things is grossly incomplete.

John 14:2 :: In my Father's house are many mansions: if it were not so, I would have told you. I go to prepare a place for you.

Offline nogodsforme

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Re: homosexuality and evolution
« Reply #2 on: March 17, 2014, 03:41:28 PM »
The classic conservative line is that gayness is based on sinful choices--gays are just plain ornery; the old liberal line was that gayness was caused by bad family upbringing, like weak father/strong mother, or molestation as a child.

Neither environmental explanation accounted for: why gayness appears in many animal species where bad parenting and sin don't matter, why gayness is no big deal or even expected in some cultures (ancient Greece), why gayness persists even in places where the penalties are so severe that the idea of freely choosing it would be absurd (Uganda, Saudi Arabia) or why some families produce one gay kid, others several and most none.

Add the anecdotal evidence that many gay people always knew they were gay-- and their families always knew, too. Seems like something genetic might be happening there.....

I know a family where both of the kids are gay, the older brother and the younger sister.   :?
Extraordinary claims of the bible don't even have ordinary evidence.

Kids aren't paying attention most of the time in science classes so it seems silly to get worked up over ID being taught in schools.

Offline ParkingPlaces

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Re: homosexuality and evolution
« Reply #3 on: March 17, 2014, 04:15:15 PM »
My knowledge of genetics is only at the lay level, but I see no reason why there couldn't be a common genetic variation that causes an individual to prefer their own sex over the opposite one. Red hair, blue eyes, lots of genetic differences exist that have no specific reason for being, but just are. And as long as a genetic trait doesn't bring an end to the species, it does not have to be procreation-centered.

I tend to suspect that in some cases (as per gays who have told me they always felt gay), and in some cases the tendency to prefer being gay may be amplified by social situations, like being younger brother or something. Like many things in this world, I doubt that there is only one cause.

Not everyone is entitled to their own opinion. They're all entitled to mine though.

Offline Chronos

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Re: homosexuality and evolution
« Reply #4 on: March 17, 2014, 09:41:13 PM »
My knowledge of genetics is only at the lay level, but I see no reason why there couldn't be a common genetic variation that causes an individual to prefer their own sex over the opposite one.

... or both, or none at all, or a variety of other things ... that are not "normal" ...


John 14:2 :: In my Father's house are many mansions: if it were not so, I would have told you. I go to prepare a place for you.

Offline nogodsforme

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Re: homosexuality and evolution
« Reply #5 on: March 18, 2014, 03:09:04 PM »
Some very interesting evolution-related research on how traits can be emphasized and preserved is breeding dogs from other canids like wolves and foxes. In the fox study, the researchers only allowed breeding between the animals who were friendly to humans.   http://blogs.scientificamerican.com/guest-blog/2010/09/06/mans-new-best-friend-a-forgotten-russian-experiment-in-fox-domestication/

One simple trait, friendliness-- did the fox let you get close and pet it or did it try to bite you and run away? That was it. They continued this over the next 40 generations. And they found that the later foxes looked and behaved more like dogs and less like foxes!

They also found that nearly all animals domesticated by humans-- like cows and sheep--  not only behave differently--they also have a different appearance from their wild cousins. Softer fur, shorter fluffier tails, smaller size, larger eyes, floppier ears, flatter faces, even less strong smelling. We would expect them to act differently because we are choosing based on behavior.

But what would cause them to look less fierce and aggressive, like a more baby-like version of the wild animal?  Apparently, we humans prefer the baby version of the animal more than the adults, and that is what we get. Dogs are like permanently baby wolves and foxes. All changes that make an animal more like what humans want come along with whatever it is that makes the animal more friendly to humans.

What does this have to do with gays? Maybe there is something that produces gayness (which is maybe useful in group survival although not useful individually) in animals and humans that travels along with other specific traits that get passed along. Like the aforementioned eye and hair color. And you can therefore choose to be gay or not, exactly  the same way you can decide to be born with blue eyes and red hair.... ;)
Extraordinary claims of the bible don't even have ordinary evidence.

Kids aren't paying attention most of the time in science classes so it seems silly to get worked up over ID being taught in schools.