[…] – likely most of which are unknown (75% – 99% being unknown in stool samples) – may exert huge impact on human behavior. Indeed, we are learning that gut flora may play a considerable role in health, obesity, and […]

The water starts off muddied. Simple obvious correlations uncomplicated by other factors are common in theories, rare in the real world.

You said that

“there were significant associations with the woman masturbating or practicing cunnilingus in the past month.”

for women with vaginal yeast infections. But, you didn’t mention the effect sizes. What were they? 1% higher rates? 10%? 100%?

Just the mere fact that something is statistically significant, doesn’t mean it is worth mentioning as a piece of data. It’s just muddies the water to present effects that are orders of magnitude apart as if they are equally important.

[…] SSA? Absolutely, especially if the true heritability turns out to be truly low. See Peter Frost (Yes, Demons Do Exist). Perhaps the recent trend towards more women displaying SSA is due to the spread of a new […]

[…] en personalidad, disminución paradójica de la movilidad social, la amenaza de nuevos patógenos (sí, los demonios existen), el infraestudiado problema del altruísmo patológico y un largo etcétera de limitaciones que […]

[…] Demons exist! […]

Interesting virus that slows brain activity. Of course, according to the researcher, nothing to worry about…

One might consider whether actual demons had a hand in the evolution of ‘demonic’ pathogens.

You might have that correlation between the yeast infection and masturbation backwards. A woman who masturbates more likely is introducing (and perhaps reintroducing fugal infections from other parts of her body to her vagina).

It makes sense that if a woman does not masturbate as much she’ll have less chance of contamination.

I was speaking tongue in cheek.

Given how many people think the only way for new diseases like ebola or HIV to arise is through bioweapon programs, it was perhaps understandable that some misunderstood you.

“Perhaps this is an argument for intelligent design. After all, only an all-knowing designer could have made creatures that are so small and yet capable of so much”

Hm, no. Looks like evolution through natural selection is a perfectly adequate explanation.

Or perhaps monogamy is the human evolutionary response to parasites.

How did ‘we’ observe homosexual behavior in pre-Colombian America?

Interesting idea, that sexually transmitted pathogens can alter human behavior by directly messing with the nervous system. But I think a far more likely explanation for today’s wildly shifting sexual mores is that it’s the result of culture, what’s considered socially acceptable now.

I like to think that promiscuity is a sin against God and that STDs are part of the wrath of God.

This reminds me of my speculation that birth-control may be triggering an innate behavioural tendency to seek new partners if your current one seems infertile, i.e. if you are having sexual intercourse with them over an extended period without getting pregnant. Does anyone have any thoughts on the evolutionary plausibility of such a mechanism?

I think it is more like partners are more likely to break up when they get tired of each other IF they don’t have any offspring. BUT if they do have offspring, then they will stay together for the sake of the offspring.

The ID version involves putting tab C into slotB.

You haven’t proved causation in some of these cases; maybe there’s something in semen that makes the vagina more hospitable to Candida, or something like that.

That said, the overall idea seems pretty credible. We know chemicals like alcohol can make us do things, and microbes can secrete chemicals, so…

I’m pretty sure the Romans had their own version of “cuckoldry,” or at least swinging, which amounts to the same thing, biologically speaking. Suetonius and Petronius have examples, and Martial probably does too.
Also: Eskimos. Off the top of my head: Marco Polo mentioned it among some tribes in his travels. And while Cassanova was later than what you mention, he seemed to enjoy the kick, bug-magnet that he was.

Because A and B will have had frequent sexual relations, and therefore any sexually transmissible pathogen either has is likely to be shared.

By the way, Captain Kidd is alleged to have had cuckold fetish, and that would fit with the narrative here.

‘I sleep only for Maecenas!’ and The Flying Yorkshireman inviting a storm giant home to get a pup off him, imply happy cuckolds rank social success above genetic success.

Its the Demiurge, the God Architect who created this World. According to Gnostics this is a Evil God who appears in The Old Testament as the Genocidal Yahweh.

Jesus knew the higher God.

I just utterly fail to see how the phenomenon of a bacteria, virus or fungus possessing the ability to change the behavior of a host is any different in any way, shape or form from the possession of any other creatures’ abilities and thus changing, much lending any more weight (if there be any at all)—to the “intelligent design” argument. None. Show some inability for evolution through natural selection to give them that ability and you might be getting somewhere, but that is nowhere in evidence. Indeed, the very *desirability* that a bacteria, virus or fungus would want to have to change a host’s behavior seems to me to be strong evidence that indeed that ability did come about through natural selection and evolution.

Moreover, it’s a piquant thing to see the intelligent design idea, which of course seems nearly uniquely pushed by those wanting to preserve the traditional idea of supremely human-friendly God, now being invoked as the possible explanation for giving microbes and etc. the diabolical ability to deprive humans of their free will and essentially render them into slaves, especially sexually.

Indeed, is there any *better* way than to turn the idea of an Intelligent Designer sour in the mouths of most of those pushing same than if you could show that such bugs exist which, if one is a Believer, must therefore must have been created by an Intelligent Designer who has then made lots of sexual behavior not a matter of free will at all but instead a matter of irresistible slavery?

Hilarious.

I’m just speculating wildly here based on no evidence whatsoever:

If A and B are married, they will have had sex multiple times; thus, the probability that they both will be infected with the pathogen will be much higher than the probability of any two randomly chosen people both being infected with it. The pathogen could could affect A in the manner described in the article and affect B in a slightly different manner that increases the likelihood that she’ll be into having sex with another male in the presence of her husband.

Apari et al. (2011) argue that infertility causes the host and her partner to break up and seek new partners…

This reminds me of my speculation that birth-control may be triggering an innate behavioural tendency to seek new partners if your current one seems infertile, i.e. if you are having sexual intercourse with them over an extended period without getting pregnant. Does anyone have any thoughts on the evolutionary plausibility of such a mechanism?

It is a common trope in popular culture that girls with low self-esteem are easy. If this is true, then it would make sense for STIs to lower girls self-esteem. This seems to me something relatively easy for a pathogen to accomplish compared to some of the other speculations.

Do we see reversal of mate guarding in humans? Yes, it’s called cuckold envy—the desire to see another man have sex with your wife—and it’s become a common fetish. Yet it seems relatively recent. Greco-Roman texts don’t mention it, despite abundant references to other forms of alternate sexual behavior, e.g., pedophilia, cunnilingus, fellatio, bestiality, etc.

So imagine you have A and his wife B, with male C.

A wants to watch C have sex with B.

How is a pathogen doing this? I suppose that A is the one with the disease, and should want his wife to have sex with other men. But why would the pathogen expect that any disease B gets will be the same as the pathogen within A?

Seems pretty far fetched.

STI-induced infertility has exceeded 40% in parts of sub-Saharan Africa (Apari et al., 2011).

Don’t these countries still have like 7 children per woman?

It’s so crazy it has to be true.

God exists in extra dimensions at the sub-atomic level. Bacteria and microbes are the
closest living embodiments of God. We’ve had it backwards all the time.

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HIV might be a good candidate for investigation. Severe cognitive impairments are observed in sufferers, but it may be that more subtle behavioural changes predisposing towards risk-taking and hyper-promiscuity occur earlier.

G.Cochran again WHEN the normal bacterial flora of the colon are hammered by a broad-spectrum antibiotic, C. difficile often takes over … bacteriotherapy, more commonly called a stool transplant, works like gangbusters, curing ~94% of patients."

I think a major problem for rogue bacterial vaginosis and vaginal yeast strains' sexual transmission would be the normal flora in the vaginal environment. I seem to have read somewhere that douching is likely to result in infections.

Still, it is interesting that "C. albicans traffics to and infects the brain by binding to gp96, a unique receptor that is expressed specifically on the surface of brain endothelial cells."

Morphometric face analyses of schizophrenics don't seem to be similar to the shape morphs for 2D:4D –

http://www.sciencedirect.com/science/article/pii/S000632230601119X –

"Both male and, particularly, female patients evidenced significant facial dysmorphology.

There was narrowing and reduction of the mid to lower face and frontonasal prominences, including reduced width and posterior displacement of the mouth, lips, and chin; increased width of the upper face, mandible, and skull base, with lateral displacement of the cheeks, eyes, and orbits; and anterior displacement of the superior margins of the orbits."

In general, if you search for 2D:4D and schiz you generally fin – "More 'feminized' 2D:4D phenotype has been demonstrated in schizophrenia versus same-sex controls."

This reflects the prenatal picture.

Serum t levels are not obviously high in identified schizophrenics, but there is some speculation present online that high serum levels can predispose to onset (and wouldn't necessarily need to be high after that).

One issue with women, men and schiz is that women much more often manifest borderline schizophrenia / borderline personality disorder, which most shares a genetic etiology with schiz out of various psychiatric disorders.

A major difference between these disorders is that the distorted thinking of BPD is layered onto the intentions, emotions and actions of other people, which may reflect and interaction of a basically similar problem with greater female tendencies towards negative emotion (neuroticism) and greater interest and affection in other people (agreeableness / sociability / interdependence).

Toxoplasma gondii and the blood-brain barrier involves intracellular transport, anon.

Schizophrenia is virtually unknown before puberty and the highest rates are in the early twenties, when sex hormones reach their highest levels and exert the maximum neuroexcitatory effect.

ACCORDING to G. Cochran: "Schizophrenia is more common in men than women – about 1.4 to 1." and there is a "higher rate of diagnosed schizophrenia among blacks… Afro-Caribbeans (as much as 15 times higher…)".

Men have more testosterone than women, and black Africans have higher levels of testosterone.
So, it has something to do with prenatal inflammation (that can be due to causes other than infection; see here) and sex hormones.

T. gondii moves around the host’s brain and alters many neurons without actually taking up residence in them, apparently by injecting specific proteins through the cell wall.

Oh, Peter. Neurons do not have a cell wall. "Plasma membrane", you surely meant.

"However, genome-wide scans have revealed that genes most strongly associated with schizophrenia/bipolar risk are to be found in the mother's–not the sufferer's–major histocompatibility complex (containing the key genes for the immune system). See here and cited paper here. A recent review here. Schizophrenia strikes after puberty so sex hormones may be somehow implicated.

As I read it it's being suggested that all kinds of prenatal infections can trigger certain opposed immune responses that differ and result in a few types of brain damage, which produce just a couple of classes of syndromes. It does not seem established that differences between infection by a bug that is a manipulating brain changer (like toxoplasma) and a bug that is has not evolved for manipulation of brains are crucial in producing the specific behaviour of a paricular class of mental illness.

The best evidence for manipulation would be an epidemic of humans doing something that is contrary to their reproductive fitness, otherwise inexplicable, could spread an infection, and is specific (ie not part of a general pattern of behaviour, like schizophrenics having no concern with personal hygene). Personally, I think you have identified such a behaviour, and it exists in the real world. (not just in French farces or Catherine Millet's memoirs).

For a long time people figured that brain manipulation by t. gondii w/out evidence of oocysts was a silly argument. Not so after this latest research. Your observation that t. gondii is probably only one of many such parasites that can manipulate behavior w/out being noticed is spot on.

We may be the chosen final hosts for such parasites as are cats for t. gondii or the intermediary host as are rodents for those protozoa or we may be reproductive dead ends for many but still be subject to their machinations.

It seems more and more likely human male homosexuality that is the result of such manipulators, f not t. gondii, then something similar. (BTW, t.gondii is omnipresent in ovine flocks).

All kinds of things can affect the brain and the amygdala specifically, I already mentioned that living in a city affects its responsiveness, so does meditation.

Meditation can actually increase the amount of gray matter in the brain.

The Amygdala War: Toxoplasma gondii’s surgical strike against the amygdala
http://majorityrights.com/weblog/comments/toxoplasma_gondiis_surgical_strike_against_the_amygdala/

If being born that way exempt one from moral rules, does being infected carry the same exemption?

Given that parasitism has evolved independently over and over again among plants and animals, is it possible that it exists among human beings as either memetic or genetic strategy? E.g., parasitic professions or (gulp) ethnic groups? Orwell's Animal Farm describes bureaucratic parasitism by the pigs:

Somehow it seemed as though the farm had grown richer without making the animals themselves any richer-except, of course, for the pigs and the dogs. Perhaps this was partly because there were so many pigs and so many dogs. It was not that these creatures did not work, after their fashion.
There was, as Squealer was never tired of explaining, endless work in the supervision and organisation of the farm. Much of this work was of a kind that the other animals were too ignorant to understand. For example, Squealer told them that the pigs had to expend enormous labours every day upon mysterious things called "files," "reports," "minutes," and "memoranda". These were large sheets of paper which had to be closely covered with writing, and as soon as they were so covered, they were burnt in the furnace. This was of the highest importance for the welfare of the farm, Squealer said. But still, neither pigs nor dogs produced any food by their own labour; and there were very many of them, and their appetites were always good.

http://gutenberg.net.au/ebooks01/0100011.txt

Excellent post, Peter.

heaTaca123Correct link for effects of being brought up in an urban area here.

"The cat craze began with the cat shows in the late nineteenth century," [Torrey] explains. "And when I went back and looked at what we know about cats as pets, it corresponded almost perfectly to what we know about the rise of psychosis." I think Torrey is basically saying it's mainly down to cats, but there are description of schizophrenia in the Atharva Veda, and Hindus of 1400 BC didn't revere cats as far as I know

Flegr mentions some opposite effects in men and women. That might lead some to think there was a sexually transmitted manipulation going on. But there are also some opposite effects of toxo in humans from rural and urban areas according to Flegr.

In that Torrey set a lot of store on high rates of Schizophrenia in urban areas, what to make of there being opposite effects on rural and urban humans irrespective of sex?

I'm beginning to wonder if growing up in urban areas has a far more profound effect (apart from any pathogens) than has been realized. There has been some research suggesting that is the case: here.

As for sexually transmitted diseases altering human behavior; yes, where there was a lot of multi partner sexual activity such a disease could evolve. However, I have to wonder about how a disease from a sexually highly active population would adapt when it arrived in a monogamous population. I think in such an environment the putative disease would evolve an enhanced capacity for vertical transmission.

Okay, I exaggerated about the mutual aid. But I talk about the less severe cases and those that have traits moderate some of the symptoms of schizophrenia.

If the parasite leaves infected with a more attractive facial aspect, then it could mean that there was a good relationship of mutual aid. It seems that schizophrenia is 80% of heritability. It may be that some people actually have more genetic predisposition to develop the disorder. It could also be that some ants have evolved to be parasitized while others do not exhibit genetic predisposition.

It even mentions …

Put all that together with the pathogens we already know, like toxoplasmosis, modifying them to mess up the brain is easy.

John Ringo's latest book about The Zombie Apocalypse has behavior modifying viruses.

I don't think that polls on homosexuality are a good indicator of increasing homosexuality. These polls rely entirely on self reporting of homosexuality. Given the change in cultural attitudes, older people are far more likely to either outright lie about their sexuality or even refuse to admit it to themselves. Therefore it is not surprising that a much higher number of young people admit to being gay than old people.

"Over on Greg Cochran's blog it was pointed out that there have been individuals who suffered damage to the brain (after and accident, say) who became homosexual afterwards….There was also an article about a man with a brain tumor who became highly sex seeking and could not control himself."

It does seem to me an obvious place to start looking for the cause – bug or otherwise – would be the *mechanism* of sexual attraction.

There must be a piece of the brain that controls whether men get turned on by pictures of men or of women?

Over on Greg Cochran's blog it was pointed out that there have been individuals who suffered damage to the brain (after and accident, say) who became homosexual afterwards. While only a small number of individuals, it suggests that the target is a small part of the brain that when damaged causes males to be attracted to other males.

There was also an article about a man with a brain tumor who became highly sex seeking and could not control himself.

Skittles – That's a slightly odd argument.

What you seem to be saying is that declining sex hormone levels are responsible, but it's following a provider strategy that left humans on the knife edge of being vulnerable. But the latter proposition seems basically unnecessary – humans could've just been "on the knife" because why would nature masculinize a brain more than it is necessary to anyway, given the environment of evolutionary adaptedness?

One thing here is that the groups we would expect to be more providerish (e.g. Whites and Asians) have a lower percentage of male homosexuals (in the GSS, the Gallup Survey and the ADD Health Youth specific survey) than West Africans or Latin Americans.

addendum
Obviously the above doesn't cover sheep so there's something missing somewhere.

Ron Unz

It seems to me the bug theory has to tick certain boxes based on the premises accepted.

1) If most male homosexuals are that way from an early age then that limits the possible forms of transmission.

2) It has to effect the mechanism of sexual attraction.

3) It has to have a way of not being successfully selected against.

"If the germ somehow strongly benefitted from inducing gayness in its hosts, the theory would make sense, but I haven't seen anyone provide a logical model for this."

"The other possibility is that the orientation is an unintended side-effect of the germ's activity. But if the side-effect could be eliminated, there would be massive selective pressure on the host/germ system to do so, since the change would be very important to the host but totally unimportant to the germ. Therefore, the only reasonable model would be one in which the side-effect is inextricably linked to the germ's functioning."

I'm not sure if this idea is entirely plausible but

If the original bug evolved in a promiscuous environment as a promiscuity increasing STD that worked by manipulating the visual part of the attraction mechanism e.g. making a person equally visually attracted to flat hips as to a 0.7 waist-hip ratio, then in that environment it has a good way to spread itself.

If as a side-effect the sons of mothers with the bug had a chance of turning out with some maladjustment to their visual attraction mechanism – including exclusive homosexuality – then the people in that environment might develop an immunity to that side-effect.

If the bug then travels *outside* the original environment the people outside might not have the same immunity.

A second possibility might be the the bug doesn't cause homosexuality in the first environment but some difference between the old and new environments makes the bug mutate and it's the mutated version that can cause infected mothers to have homosexual sons (and possibly other maladjustments to visual attraction like visual ttraction to pre-pubescent children or post-menopausal women).

In the first case the second population would just not have developed an immunity *yet* because of limited exposure e.g. if it was a tropical west african virus then northern europeans would have had some exposure through sailors and merchants from the 16th century or so but only large scale exposure since mass immigration.

If so this might imply a test i.e. that populations with the most exposure e.g. American Southerners and White South Africans ought to have lower rates of homosexuality?

In the second case where the premise is the bug mutated then the original population wouldn't have the immunity and so you might expect higher rates of homosexuality among members of the original population who had moved to the new enviroment than those who had stayed behind i.e. if it was a tropical west african virus and the original didn't cause homosexuality but a version that mutated in northern europe *did* then you might expect west africans who moved to northern europe to have higher rates of homosexuality than those who stayed in west africa.

There may be a fatal flaw in there somewhere but it seems to me dual environments could possibly square the circle.

"Providing for a woman and caring for her children is less masculine than crushing your enemies, seeing them driven before you and hearing the lamentations of the women (before you "embrace" them)."

It depends on the environment.

If you're living in a rainforest where the women can gather enough food to feed their children themselves then killing that man and taking his wife is viable because you're not the one feeding the resulting children.

If you're a steppe pastoralist then killing that man and taking his wife is viable because you're also taking his herd which can be used to feed two sets of children.

If you're an eskimo then killing that man and taking his wife is entirely pointless as you can only hunt enough to feed one family.

Seems to me, pre-agriculture, most people outside the tropics will have been living in the equivalent of the eskimo environment where one man can only feed one set of children.

Just so I'm not misunderstood, I'm not trying to claim that current adult testosterone levels are related to sexual orientation.

I suspect that the effect occurs in the womb. I'm merely using that study as an example of the well documented degradation of average hormone profiles.

Providing for a woman and caring for her children is less masculine than crushing your enemies, seeing them driven before you and hearing the lamentations of the women (before you "embrace" them).

Recall that warfare used to be far more common in day to day life than it is in today's WEIRD societies. Hunter-gatherer life has been described as "constant warfare" and anthropologists have noticed that in at least some societies the violent tribesmen father the most children.

Our hunter gatherer ancestors were probably quite masculine and aggressive compared to us. It must have been quite the transition when society became more complex and elites started to be able to *EFFECTIVELY* prohibit unsanctioned violence. Previously adaptive genes for ultraviolence became maladaptive while previously maladaptive genes that produced less violent, more effeminate males became much, much more successful, leading to a dramatic increase in frequency in those genes.

Keep in mind, those guys still had far better hormone profiles than we do, on average, so they wouldn't seem effeminate to modern day people. Things only became problematic much later when environmental factors caused massive degradation of most people's hormone profiles.

http://www.gallup.com/poll/158066/special-report-adults-identify-lgbt.aspx

Per Gallup, only 1.9% of people age 65 and up are homosexual, while 6.4% of people ages 18-29 are homosexual (4.6% of men ages 18-29). Recall the study about the drop in testosterone levels. Expect the number of gay people to increase in the next generation as as average hormone profiles degrade further.

Skittleman

"As a quick and dirty solution to produce the second kind of males, their brains were somewhat feminized in the womb."

The trouble with game is all the nonsense around the word "beta."

Provider males evolved in environments where hunting was necessary to feed the children. There's no reason for those behaviors to evolve otherwise.

What game calls "alpha" behavior is male behavior from environments where the males were literally useless. It's because they were useless they evolved peacocking behaviors.

In the modern environment provider males have to a large extent lost the niche they had for thousands of years but there's nothing feminized about them.

Evolution made some men more masculine than others. Not just in terms of their bodies, but in terms of their brains. It is not ideal for all males to follow a super aggressive reproductive strategy, like Ghengis Khan. Alternative, more peaceful strategies evolved, such as faithfulness to a woman and investment in her children. We see these alternative mating strategies in many species.

As a quick and dirty solution to produce the second kind of males, their brains were somewhat feminized in the womb. Evolution is fine with quick and dirty solutions, as long as they work in the environment of that time.

In the ancestral environment this brain feminization did not often produce homosexuals, because if it did it would have been selected out. With the hormone profiles that existed in the ancestral environment it quite reliably produced a more effeminate but still completely heterosexual provider male.

However, as civilization advanced, both male and female hormone profiles deteriorated because of environmental factors. For example, average testosterone levels dropped 17% between 1987 and 2004. They may have dropped a lot more than 17% between 1900 and 2013 (or whatever).

http://jcem.endojournals.org/content/92/1/196.abstract

In this new environment, old genes had new effects. Men became less masculine overall. The guys whose genes were coded for a Ghengis Khan strategy still came out relatively masculine, but the guys whose genes were coded for more feminized brains were at risk.

The effect that used to produce a slightly feminized brain following a provider strategy was no longer completely reliable in the era of degraded hormone profiles. It occasionally went too far and produced males with excessively feminized brains that had female-like sexual attraction mechanisms.

This flaw is currently being selected out of the population, but it has a long way to go because hormone profiles keep getting worse and worse, making new sets of formerly beneficial genes vulnerable to the problem. That's why young men are much more likely to be homosexual than older men.

Seems likely. Do I win something?

> The pathogen does not benefit from the host being gay, but the host loses, so the pathogen is essentially pursuing a kind of mutually assured destruction policy

That kind of makes sense. You know, the eye, the gonad, and the brain are called 'immunopriveleged' because immune tone is low there. The reason it is low is because you are going to wind up pretty much 'darwinianly dead' if the immune system causes severe collateral damage to those sites — even if you remain very much alive in a normal sense.

Some highly evolved and successful parasites therefore like to hang out in the brain, generally without ravaging it.

Well, it is conceivable that some areas of the brain, those most crucial to fitness, are more immunopriveleged than others. That would possibly be an even cooler place to hang out (than the brain in general), where you are even less apt to be eradicated by immunity.

How immunoprivelege works is understood, at least in part. The privileged tissues present special ligand molecules which bias certain white blood cells towards apoptosis (suicide) or anergy (lasting or permanent inactivity). Well, if the brain, eye, and gonad generally express such ligands at density x, some key parts of the brain might well express them at density 5x, or 4.23986x.

"The main argument against the naive Gay Gene model is that there would be strong selective pressure to weed out such genes."

I've never understood what was wrong with saying that social stigma against homosexuals historically forced them into marriages where they reproduced anyway. The stigma prevented the normal weeding processes from working. This kept the gene around despite its normally maladaptive consequences.

Ron unz, I'd say Occam Razor is an argument FOR the germ theory.

Anon at 1:54:

The crazed state of the rabies victim is not a "side effect"; it's an actual evolved strategy of transmission.

Deafness, testiular atrophy, encephalitis, ovarian inflammation, pancreatitis, etc. do not help MM&R spread, which is why they are termed "side effects."

Damaged heart valves are not strategies for transmitting bacterial infection in rheumatic fever or in endocarditis. They are side efects of the infections.

Apart from its obvious scientific plausibility, I like this theory for the lulz. It is perhaps the Ultimate Un-PC Hate-Thought Ever Thunk, ever. All that self-importance, all that self-righteousness — and it may all turn out to be a simple micro-organism. Parturiunt montes, nascetur ridiculus virus.

The model proposed by one of Cochran's commentators is that it actually doesn't, but it does mimic the body in such a way that evolving a response to it would render the host sterile, because the immune system would end up targeting both the bug and the parts of the brain responsible for successful sexuality.

The pathogen does not benefit from the host being gay, but the host loses, so the pathogen is essentially pursuing a kind of mutually assured destruction policy (your victory, immune system… so pyrrhic!)

Same anon here.

Couple of other facets here which may be interesting:

If this were true, then one implication is that the gays would not be the carriers of the pathogen, the straights would.

This makes transmission to pre-gays very easy, because they would not actually have to come into contact with gays, in fact, the more they come into contact with straights, the better.

It would also make any intervention against any pathogen easier in a sense, as it would not be reliant on any consent by the gay community, because the bug is in the bodies of straight people (the straight people are the infected, while gays are those who are all clear, but whose sexuality was lost in the process).

Another facet might be that this might link up with testosterone levels – that is to say, if testosterone suppresses the immune system (somewhat skeptical of this but lets run with it) and homosexuality is an auto-immune response, then gays being somewhat low testosterone in some ways might make sense.

But I would suggest that a similar problem may be found in the Gay Germ model. If the germ somehow strongly benefited from inducing gayness in its hosts, the theory would make sense, but I haven't seen anyone provide a logical model for this.

The model proposed by one of Cochran's commentators is that it actually doesn't, but it does mimic the body in such a way that evolving a response to it would render the host sterile, because the immune system would end up targeting both the bug and the parts of the brain responsible for successful sexuality.

The pathogen does not benefit from the host being gay, but the host loses, so the pathogen is essentially pursuing a kind of mutually assured destruction policy (your victory, immune system… so pyrrhic!)

But then, still why is this only in humans?

The problem I am still having with the Gay Germ idea even after all the discussion at Cochran's blog, which convinced me a lot more than I was otherwise, under this theory:

The mechanism for choosing and successfully mating with humans must be very simple, assumed to be identical with other species, no different.

This is not really for any particular evidence based reason, but because more complex the mechanism becomes, the more vulnerable it is to load and sexually antagonistic selection, to the point where genetic hypotheses may begin to become possible. (Of course, it is arguably parsimonious as well)

However, if the mechanism is the same in humans, with no particular extra complexity, then why are humans the only ones to get the gay? And sheep? A Gay Germ should work everywhere right? If it's hard for humans to evolve a response, why would other species have an evolved response? Our herd sizes are pretty large, as one point, I suppose, but how would that link in.

If human sexuality (targeting and mating) is conversely, very complex and different from other animals, then….

Can you explain how the lasting deleterious side effects of the measles, mumps, and rubella confer a selective advantage to each bug? I admit I don't understand what you're saying.

Something like rabies. The rabies virus makes the infected animals very aggressive and bite prone. The aggressive behavior and biting helps the virus spread to other animals.

Even something like sneezing or coughing, which we tend to associate strictly as a defensive or immune response, could be seen as something a bug causes and relies on to spread.

Gay men got less pre-natal testosteronisation; their fetal programming is maladaptive. If there was a bug that caused oestrogenisation then it could be reducing the reproductive fitness of men by making them less masculine, and sometime tipping them into homosexuality. But, in women it could spread through vertical transmission, and increasing reproductive fitness though making infected female fetuses more feminine. Do gay uncles have sexy sisters?

Ron Unz,

Can you explain how the lasting deleterious side effects of the measles, mumps, and rubella confer a selective advantage to each bug? I admit I don't understand what you're saying.

Mark,

My understanding is new HIV infections continue among the gay male populations.

In other words, as son as retrovral meds improved, old behasviors returned. As long as the unpotected sex and promiscuity continue,you can look for the next bug to evolve to deadliness.

I feel like Cochran's pathogen, if it exists, plus HIV make for a weird and tragic symmetry in the lives of many gay men. Or did, back when HIV was terminal.

I remember reading that the concordance of rheumatoid arthritis among MZ twins is 15-18 percent, an incidence not that different from that of MZ twins for homosexuality.

It's seems clear from studies on MZ twins that there is some enviromental trigger for RA, and it seems likely tye same is true for male homosex.

You say that Cochran believes a pathogen alters the host's orientation in order to spread, but that is not what he's been saying ; this is not the first time I've heard you present his idea as such. He's said many times that the more likely scenario is that the damage to some critical cells is more likely a side effect of a common childhood pathogen, collateral damage, as it were, rather than a strategy of the bug to survive and spread.

Seems plausible that a unique environment – female provider – might lend itself to some unique bugs.

Didn't Jesse Jackson assure us that the CIA created AIDS?

"OKCupid took this chart down from their blog, but Very Short, Very Tall Men More Likely To Be Gay"

I.E…. there are a lot of gay men(and women really) who are gay because they are(or were when they were being socialized) not sexually attractive to the opposite sex.

I don't believe in either the gay germ or the group selection(gay uncles invest in nephews) theory…I believe it is a socialization/hormone/dopamine issue….

OKCupid took this chart down from their blog, but Very Short, Very Tall Men More Likely To Be Gay

http://www.akawilliam.com/study-very-short-very-tall-men-more-likely-to-be-gay

The heredibility of homosexuality is about 20% not the 35-40% given(see Cohran at westhunter). Ther is a lot of PC nonscience in reported figures