Homosexuality a Pathogen ?

[*PhilHos*]

(05-19-2016, 07:32 PM)Rotobeast Wrote: First off.... I'm not subscribing to this theory and imagine it's propaganda.
I had not heard of it and figured I would share this post from another forum.
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Gregory Cochran, physicist and adjunct professor at the university of Utah has developed the hypothesis that homosexuality is caused by a pathogen [1] - either a virus or a bacterium. There are several good reasons to believe this may be the case.

- The low hereditability of homosexuality (0.22) [2]
- The absence of homosexuality in hunter-gatherer populations
- The relatively high frequency of homosexuality (~4% in the west)
- The lack of any plausible evolutionary explanation.

In short, a lack of sexual interest by males in females would be an evolutionary penalty. If it were caused by a 'gay gene', the trait would have been selected out long ago because of a lack of reproductive fitness. Also, the frequency is too high to be caused by a mutation.

There are various examples of infectious agents altering behavior: [3]

- Rabies causes dogs to be more aggressive in the final stage of the disease.
- Influenza causes humans to be more social in the days prior to the noticeable effects.
- Toxoplasma causes rats to be (sexually) attracted to cat urine.

There are many more examples of behavior-altering agents (mostly viruses). This leads us to the conclusion that a pathogen changing sexual orientation is far from impossible. It would explain the frequency in western population and the absence in hunter-gatherers.

Furthermore, there is the interesting phenomenon of homophobia. Homophobia isn't an actual phobia, but an aversion of gays. Interestingly, homophobia actually is heritable, much more so than homosexuality (around 0.5) [4]. If it is heritable, what purpose does it serve? In particular, what purpose does it serve if homosexuality is caused by a pathogen?
Research has been done on the nature of homophobia, and this research has found that it exists strongest with regard to homosexuals' contact with children. A subjective 'degree of discomfort' was found much higher when confronted with a scenario of gay people who hold a profession that involved contact with children (such as pediatrician or teacher) than with gay people who were e.g. lawyers or construction workers. A second study showed that for different types of medical doctors, a high degree of contact with children (e.g. child psychiatrist) induced more discomfort than an invasive procedure (e.g. brain surgeon) but only for gay doctors. Two more studies clearly suggested that homophobia is aimed at preventing children, particularly younger children, from being exposed to homosexuals. [5]

What if homophobia is aimed at preventing the spread of the pathogen that causes homosexuality?

Cochran asserts that it’s not likely that the pathogen is spread by homosexual sex. How the putative pathogen is spread is not clear at this time. Even less clear is whether there is a “critical period” for this infection to affect sexual orientation. It’s also not clear how prevalent the pathogen is in the population, or what percentage of infected individuals become homosexual.

Regardless of how the pathogen is spread, it likely that extended periods of fairly close contact with an infected individual is more likely to result in transmission of the infectious agent. If there is a critical period of time, say some time in childhood, for an infection to result in sexual orientation being altered, the evolutionary purpose of homophobia starts to become more apparent.

Indeed, the existence of homophobia may stand as pretty good evidence in support of Greg Cochran’s pathogenic hypothesis for homosexuality. Indeed, for as many have pointed out, homosexuals are otherwise harmless and indeed perhaps beneficial to other males in the group (reduced competition for females, for example). That gays are nonetheless hated seems hard to explain otherwise.

One possible way to test Cochran’s hypothesis is to observe if there is a higher incidence of homosexuality among the adopted children of homosexuals. Using adoptees controls for heredity, and presumably, sharing a household should give plenty of opportunity for the pathogen to be passed on to the adopted child. Ideally, the study should look only at children adopted very young, from strangers (to minimize selection bias among the adopted children). If higher rates of homosexuality were observed among these adopted children, it would point to some environmental factor – the most likely being infection.

The low, but non-zero heritability of male homosexuality may be indicative of some sort of genetic susceptibility to the pathogen, perhaps through weakened defenses or a vulnerable neural architecture.

If homosexuality is indeed caused by an infectious agent, it would have broad implications for society, particularly the prospect of being able to prevent homosexuality (perhaps through a vaccine).

[1] https://westhunt.wordpress.com/2012/02/16/depths-of-madness/
[2] http://www.mygenes.co.nz/whitehead_twinjhs.pdf
[3] http://www.theatlantic.com/magazine/archive/2012/03/how-your-cat-is-making-you-crazy/308873/
[4] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2292426/
[5] http://blogs.scientificamerican.com/bering-in-mind/natural-homophobes-evolutionary-psychology-and-antigay-attitudes/
[6] https://jaymans.wordpress.com/2013/01/12/a-gay-germ-is-homophobia-a-clue/

Interesting, but I highly doubt that homosexuality is a pathogen.