I don't know if this has ever been posted here before. I found his "Homosexuality to me" much better than mine. Very interesting reading.

As a NUB to this, this is my first time reading it.

An Evolutionary Look at Human Homosexuality

An Evolutionary Look at Human Homosexuality

Gregory Cochran

posted 9 Jan 2005

The first key idea is that evolution optimizes function. It makes things work. If there is a change in a gene that helps the organism, that change increases over the generations, becomes more common. If it causes trouble, as most changes do that make any difference at all, the change decreases over the generations, becomes rare. So although changes (mutations) happen, they don't happen very often, and natural selection tends to keep them rare. You could think of it as a filter, constantly removing changes that don't work. It magnifies the rare changes that improve things.

When we say that a mutation, a gene change, helps or hurts the organism, what we really mean is that it helps or hurts the organism reproduce. Reproduction is the currency of natural selection: a gene that made you long-lived, happy, and sterile would never become common. 'Good' means good at being passed into the next generation. Good genes are a recipe for all kinds of complex functions, and for good health - but from an evolutionary point of view, strength and health are just means, while babies are the end product.

So you don't expect defective genes to be the main cause of human disease, and they aren't. They do cause some genetic diseases which fall into two categories.

The first is simply the consequence of the fact that mutations happen: you might call it the noise in the system, the inevitable price of imperfect gene-Xeroxing. This means single-gene Mendelian disorders like classic dwarfism or muscular dystrophy, and I suppose I would include chromosomal disorders like Down's syndrome. Maybe 1% of the population (In Europeans say) has some Mendelian disorder, mostly mild ones, but no single disorder is at all common.

The second category consists of mutations that are surprisingly common -- because, it turns out that they offer carriers some advantage, usually protection against some really unpleasant infectious disease. The most famous of these is the sickle-cell mutations, which protects carriers against the worst forms of malaria. We know of a number of others. Most are also malaria defenses (G6PD deficiency, alpha- and beta-thalassemia, etc.); some protect against other things. Cystic fibrosis probably protects against typhoid. We pay a lot of attention to them, because they are much more common than other genetic diseases, but they are atypical. They are common because they are actually useful in certain situations, rather than being an expression of the noise in the system. They are only important in populations whose ancestors have lived with malaria for many generations. For comparison, the most common disease of this sort in people of European ancestry is cystic fibrosis, which maybe hits one in 2500 kids, but sickle cell anemia can hit more than 1 in 100 kids in much of Africa, in some places one in 30.

How can we use this information to understand disease? Well, in the first place, if genetic problems were the only kind of problem we had, most of us would hardly get sick at all. The second point is that it gives us a new notion of what a disease is - anything that interferes with reproduction.

How could a serious disease be common, if evolution is always optimizing everything? Well, if it hit you at age 85, selection wouldn't be very good at filtering it away. People have already had their children by then ... So this optimizing process works less well at advanced ages. Which is the basic explanation for aging.

But how could a serious disease be common in early life? And think of it as we do - how could a condition that reduces or eliminates reproduction be common in early life?

First we have to say what 'common' means, in this context. Common means common compared to the noise in the system. So 1% is very common: no disease caused by random mutations is anywhere near that common. 1 in 10,000 is surprisingly common, but there are one or two mutation-caused diseases that are in that ballpark, like Duchenne's muscular dystrophy. Turns out that the gene involved in muscular dystrophy is maybe 20 times longer than the typical gene - there are more opportunities for typos. So 1 in 7000 boys have Duchenne's muscular dystrophy - that's as common as a 'system noise' disease gets.

A disease caused by a malaria defense gene can exist in up to a few percentage of people in a high-malaria region: but only there. No other disease has hit as many people as hard, no other disease evokes such high frequencies of expensive genetic defenses.

A common disease can be caused by something new in the world, something to which the human race has not had a chance to adjust. Most lung cancer is caused by cigarette smoking - but cigarettes just haven't been around for many generations.

Most common and serious diseases that have been around a long time and hit in early life are caused by germs - bacteria, viruses, parasitic worms, etc. Evolution doesn't necessarily make them rare, because evolution is playing on both sides in this struggle: they're evolving too. In much the same way, evolution doesn't just make zebras faster, it makes the lions faster too. Lions can continue to be a major problem for zebras over millions of years - and in the same way, malaria can continue to be a problem for humans indefinitely.

So if a disease is common (> a tenth of one percent), hits in early life, has been around a long time (so we know it's not caused by some new industrial chemical or whatever), and it's not restricted to people from the malaria zone - it's probably caused by some bug.

But what about homosexuality? Well, from this biological perspective, it's surely a disease. Disinterest in the opposite sex reduces reproduction quite a bit - around 80% in American conditions. Does it hit in early life? Sure. Has it been around a long time? Certainly. Do you find it in non-African populations, people who never lived with malaria? Yes.

So it's a bug.

Now that we know that human male homosexuality looks like a disease caused by some infectious organism, the next question is how that could happen - how could some virus change sexual interest?

I don't think that anyone can be sure of the exact mechanism at this point. I think we can be fairly confident that it is caused by an infectious organism, from the information we have and general evolutionary considerations, but infectious organisms can cause harm in many different ways. Malaria colonizes and uses up red blood cells, diphtheria and cholera manufacture toxins, HIV slowly knocks out a key subpopulation of the immune system, leaving you defenseless against many other pathogens, while certain papillomavirus strains deregulates cell division and thus cause cervical cancer. And those are just samples: there are many pathogenic mechanisms involved in infectious disease, some not well understood.

What do we know? We have a lot of indications that there has been some change in the brain. After, all that's the most logical location for the cause of a change in behavior. Simon LeVay and others see differences in hypothalamic nuclei (similar to those seen in sheep). There are associated changes - the lisp, increased neuroticism and depression, etc. Somehow the cause is affecting the brain.

Just as important are all the things we don't see. We don't see IQ depression, we don't see epilepsy, we don't see convulsions, and we don't see aphasia. Clearly there is no gross trauma - somehow, the brain has been damaged, but in a very limited and focused way. A key function has been messed up, which gravely impacts reproductive fitness, but homosexual men can still hold down jobs, including very complex jobs. The overwhelming majority of mental functions are perfectly intact, or at most subtly changed. The damaged neural subsystem could be male-specific.

Do we know of diseases in which there are very specific targets - in which certain cell types are damaged or destroyed while neighboring cells are left intact? Sure. In some cases, a pathogen targets a particular cell type and has little effect on anything else. Human parvovirus (also known as fifth disease) hits erythroid precursor cells (the cells that manufacture red cells) and temporarily inhibits red cell production. In type-I diabetes, it seems likely that Coxsackie virus infections (in people with a genetic predisposition, in which HLA type plays a major role) trigger an autoimmune disease that gradually (over a year or so) destroys the islet cells which produce insulin. Other cells are not much affected.

We know of a similar, very specific damage pattern in the brain - Narcolepsy

In Narcolepsy, most of the neurons that produce hypocretins (neurotransmitters) have somehow disappeared. There are only 30,000 of these neurons in the first place, all in a small hypothalamic nucleus. This loss leaves one pathologically sleepy, subject to cataplexy and in some cases hypnagogic hallucinations. Narcolepsy hits about 1 in 2000 people: identical twin concordance is around 25%. Almost all narcoleptics have a particular HLA type, one shared by about a third of the general population. Narcolepsy (almost always) is not present at birth but manifests in early adulthood.

Narcoleptics are pathologically sleepy, but most mental functions are unaffected.

There is at present a strong suspicion that narcolepsy is an autoimmune disease, possibly triggered by a viral infection. The HLA association points in this direction, but as yet the exact cause of the destruction of the neurons that make hypocretin is unknown. Narcolepsy does, however, show that there exists some mechanism that can destroy a particular hypothalamic neuron subpopulation without causing general brain trauma.

Narcolepsy can also be caused by a mutation in the gene for hypocretin or its receptor: so far, out of hundreds of narcoleptics examined, just one had such a mutation. Of course natural selection keeps such mutations rare. He had an unusual profile, being narcoleptic from birth.

Imagine a neurotransmitter that plays a key role in male sexual behavior, produced by a few specialized neurons, probably in another of the many known hypothalamic nuclei, quite possibly in the nucleus that LeVay studied... Obviously you can walk and talk without it - women probably don't have any at all, while children may not have much. You could live without it, think without it - just as eunuchs live and think without much testosterone. But this hypothetical neurotransmitter is more specialized than testosterone: instead of beginning a chemical cascade that has many effects on body and mind, like testosterone, this one mainly affects the choice of sexual partner: is involved in constructing a search image.

Occasionally a pathogen, in one of a few possible ways, causes the destruction of most or all of those specialized neurons. Maybe its molecular mimicry: maybe it has a tropism for those particular cells and kills them directly. But this kind of super-precise damage pattern can happen, because it does happen with narcolepsy. Maybe the HLA genes make a difference, maybe they don't. As in so many things in the male brain, the search image generator is by default female-type: doing nothing, failing to masculinize, results in sexual interest (testosterone is still being produced) but it's interest is in males, not females.

Fortunately, we have an excellent experimental animal model: sheep. Some rams, 6 percent in some herds, show sexual interest in males and no interest in females, ever. Breeding experiments, using artificial insemination, showed insignificant heritability. Studies of the sheep's brains show oddly differential hormonal activity in certain areas of the hypothalumus. OSU professor studies sexual preference in sheep.

Preferential homosexuality, sexual interest in males, rather than females, is very rare. The only two species known to exhibit this behavior, at the-few-percent level, are men and sheep. It may be worth noting that men and sheep have often been found in close association.

Another point worth mentioning is that the prevalence of homosexuality probably varies a lot. It seems to be considerably more common in young men who grew up in urban areas than in rural areas, something like a factor of three, which is also true of Schizophrenia. This is a much bigger effect than the birth order stuff. If you look out in the real sticks, say among the Kalahari Bushmen, there doesn't seem to be any at all. Typically, hunter-gatherers have trouble believing that homosexuality actually exists.

All this is speculative, of course: but the idea that male homosexuality is caused by a pathogen makes good evolutionary sense, unlike every other explanation ever proposed. This particular form of pathogen explanation of homosexuality, inspired by the recent breakthroughs in narcolepsy research, is consistent with the low identical twin concordance for homosexuality, with geographical variation in its incidence, with some observations of volume changes in a particular hypothalamic nucleus in homosexual men, and most importantly, with the dog that didn't bark - the fact that homosexual men do not suffer from general brain damage, do not show symptoms like IQ depression.

Additionally another take..
VDARE.com: 08/17/03 - Gay Gene Or Gay Germ?
The cover story of the February, 1999 Atlantic Monthly profiled Cochran and his research partner Paul Ewald, a prominent Amherst evolutionary biologist and author of Plague Time: The New Germ Theory of Disease. They argued that, for two centuries, the fraction of diseases that we know to be caused by germs has constantly increased. For example, peptic ulcers were shown in 1983 to be caused by germs—and easily cured by antibiotics. Cochran and Ewald predicted that future research will discover germs play a major role in many big, bad diseases - such as cancer, heart disease, and schizophrenia.
The New Germ Theory actually originated in 1992 when Cochran got to wondering about the causes of male homosexuality. "The only thing we've seen worse in magnitude of genetic load [i.e. homosexuality’s negative effect on Darwinian fitness] was sickle cell anemia," Cochran told me on Friday.
Male homosexuality could be a similar “self-destructive” genetic defense against a major infectious disease, just as the “sickle cell gene” defends against malaria at the price of increasing susceptibility to sickle cell anemia. But nobody knows what that illness could be. It would have to be major – and, presumably, relatively modern, like falciparum malaria, which is puzzling.
Or, as Cochran suggests, an infectious disease itself could cause homosexuality. It's probably not a venereal germ, but maybe an intestinal or respiratory germ. If it spreads like the flu, and if it needs to strike at a particular stage of development before or shortly after birth, then more male homosexuals might be born in one season than another, just as more schizophrenics are born in late winter and in early spring, especially in cities with cold winters. This should be easily testable.
It's radically unfashionable to call homosexuality a disease. But you can't think rigorously about the gay gene theory without drawing straightforward analogies to genetic diseases. Both reduce the number of descendents, which is the number that counts in evolution.
Many have reacted with horror to Cochran's theory because it implies that homosexuality might be preventable with the right antibiotic or vaccine. Parents might decide that, since they are putting themselves through all the trouble of raising a child, they ought to increase the likelihood of grandchildren.
Whether that decision would be good or bad is a very personal matter—exactly the sort of dispute that VDARE.COM heroically avoids.
But—as with race—this fear of what the public might possibly decide in the future must not be allowed to retard research now.
The truth, it is reliably reported, will set us free.

Interesting articles... Here are some other thoughts on natural selection that seem to disagree with the first articles primary assumption that evolution/natural selection works towards a perfection of function.

Misconceptions about natural selection


Misconceptions about natural selection
Because natural selection can produce amazing adaptations, it's tempting to think of it as an all-powerful force, urging organisms on, constantly pushing them in the direction of progress — but this is not what natural selection is like at all.
First, natural selection is not all-powerful; it does not produce perfection. If your genes are "good enough," you'll get some offspring into the next generation — you don't have to be perfect. This should be pretty clear just by looking at the populations around us: people may have genes for genetic diseases, plants may not have the genes to survive a drought, a predator may not be quite fast enough to catch her prey every time she is hungry. No population or organism is perfectly adapted.
Second, it's more accurate to think of natural selection as a process rather than as a guiding hand. Natural selection is the simple result of variation, differential reproduction, and heredity — it is mindless and mechanistic. It has no goals; it's not striving to produce "progress" or a balanced ecosystem.
Evolution does not work this way.

This is why "need," "try," and "want" are not very accurate words when it comes to explaining evolution. The population or individual does not "want" or "try" to evolve, and natural selection cannot try to supply what an organism "needs." Natural selection just selects among whatever variations exist in the population. The result is evolution.
At the opposite end scale, natural selection is sometimes interpreted as a random process. This is also a misconception. The genetic variation that occurs in a population because of mutation is random-but selection acts on that variation in a very non-random way: genetic variants that aid survival and reproduction are much more likely to become common than variants that don't. Natural selection is NOT random!

Actually though, he totally discounts it being a mutation. And there has been no genetic source for it either. His theory may cover pedophilia, zoophilia, and other deviations from the sexual norm. In the absence of any proof either way, you have to look at all information.

I mean if you consider the homosexual deviation just another variation, you have to include any other variation too.

http://www.isteve.com/Infectious_Cau...of_Disease.pdf

Search the pdf for homosexuality. I wish I had read this before I posted "my" theory.

I love how you brazenly try to pass that off as an "equal" situation...
"absence of any proof either way"...

Like it's an equally weighted ideal to presume that some X is an example of A, and X is not an example of A. Like they are somehow equivalent ideals until proven otherwise.

By that thinking, we could label fxashun as a pedophile, and it has just as much merit as him not being a pedophile because we have an "absence of any proof either way".



Nope fxashun. It's YOUR claim. YOU prove it.
The position of others "disproving" it does not have equal merit as proving it.

And the REAL reason you can't prove it is because there is NO EVIDENCE substantiating it.
Lots of artificial circumstantial commentary, but no actual EVIDENCE to back any of it up.

Gregory Cochran, who has generated attention for his ideas in evolutionary medicine and genetic anthropology, and Paul Ewald, professor of biology at the University of Louisville, have advocated a number of pathogenic theories of disease, and conclude that this is a "feasible hypothesis". They do not assert that there is sufficient evidence to show that it is factually correct. (Crain, 1999) As of 2006, no known experiments or studies have yet been attempted.

Pathogenic hypothesis of homosexuality - Wikipedia, the free encyclopedia

And another theory which supports my much more vague theory...
Gay gene or gay virus?

"I think, however, that he overlooks an important third possibility—inadequate nutrition in utero. And, strangely, that could also explain the discordant findings among monozygotic twins—via intra-uterine competition. Intra-uterine competition? Sometimes identical twins will come out looking very different because some accident of placenta placement has caused one twin to get a far better supply of blood and its nutrients than the other twin got. And if homosexuality is caused by an abnormality of fetal brain development—as has often been suggested—poor fetal nutrition generally (including that caused by intra-uterine competition) could be the cause of it."

Wrong.
Theories have EVIDENCE to back them up.
Not commentary on a "third possibility"...

At best, this would be a "hypothesis".

It's funny how you toss out all this speculation crap, and pretend its legit.

I love how you brazenly try to pass that off as an "equal" situation...
"absence of any proof either way"...

No...By absence of proof, I mean noone know what causes homosexuality or any of the other deviances. So any theory is just that, a theory. All we know is that something is "wrong". And the "genetic" doesn't hold water either.

Like it's an equally weighted ideal to presume that some X is an example of A, and X is not an example of A. Like they are somehow equivalent ideals until proven otherwise.

While his theory hasn't been proven right, they hold more water than the "normal variation" theory. Ain't nothing "normal" about homosexuality.

By that thinking, we could label fxashun as a pedophile, and it has just as much merit as him not being a pedophile because we have an "absence of any proof either way".


Actually, I fail to reach your vaunted APA's "criteria" since I have never thought of having sex with a child. Sorry.


Nope fxashun. It's YOUR claim. YOU prove it.
The position of others "disproving" it does not have equal merit as proving it.

Give me a governmental grant, and I'll get right on that.

And the REAL reason you can't prove it is because there is NO EVIDENCE substantiating it.
Lots of artificial circumstantial commentary, but no actual EVIDENCE to back any of it up.

Gregory Cochran, who has generated attention for his ideas in evolutionary medicine and genetic anthropology, and Paul Ewald, professor of biology at the University of Louisville, have advocated a number of pathogenic theories of disease, and conclude that this is a "feasible hypothesis". They do not assert that there is sufficient evidence to show that it is factually correct. (Crain, 1999) As of 2006, no known experiments or studies have yet been attempted.

Pathogenic hypothesis of homosexuality - Wikipedia, the free encyclopedia[


Homosexuality - Wikipedia, the free encyclopedia

No one knows why people are homosexual

So his theory is just as good as any.

Pathogenic hypothesis of homosexuality - Wikipedia, the free encyclopedia

"The Diagnostic and Statistical Manual of Mental Disorders does not classify homosexuality as a disease, and the American Psychological Association affirms that it is not. These assertions mainly consider the ability of a person to function as a happy, healthy member of society, not any particular theory about the determinants of sexual orientation."

Something that I've also said. It's a socially viable but still (possibly)defective human.

The evidence is there. Circumstancial though it may be.