Monday, December 4, 2023
Mitochondrial Health

? What is known about the biology of homosexuality?

Evolutionary biologist Bryan Gitschlag discusses what is and is not known about the biology of homosexual orientation.


Here is Bryan’s twitter thread (worth bookmarking)

This paper shows there is not “A” gay gene, but that there are many genes (mutations/alleles) that influence sexual orientation:

This paper is one of many talking about evidence for the “antagonistic” hypothesis – the idea that a single gene can multiple unrelated effects (pleiotropy) and that some genes influencing homosexuality in men, have very different effects in women – the genes increase a woman’s chances of having multiple offspring:

This paper studies the antagonistic hypothesis in fruit flies (it’s found in them too!):

This paper is a survey of the prevalence of homosexual orientation across cultures:

This paper reviews many studies on homosexual behavior (not necessarily orientation) in non-human animals:


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19 thoughts on “? What is known about the biology of homosexuality?
  1. One thing I forgot to ask about during the stream. I had heard somewhere that some of the side affects of over population can trigger some animals, such as rats, to have a greater prevalence of homosexual offspring. Do you know if there is any scientific validity to that hypothesis?

    This may be related to that fraternal birth order" thing, but idk

  2. We are walking reproductive sacks with various appendages to enable us to survive long enough to reproduce. We are inherently sexual beings with out entire biological lives centered on that one goal. It's crazy to me how lost we are in relation to that one fact. I've literally heard people say things like "the purpose of life is to create art." Sorry, the "purpose" of life is to reproduce more copies of yourself. And that means in a species like ours, getting to the top of the crapheap in order to attract the best females. But in a human society full of betas and that panders to betas that gets completely lost. This is what makes life so "unfair".

  3. I wanted to watch this video when you put the notice out. Once the video came out and it was 2 hours, I said I ain't sitting through all that.

    Either break it into smaller bits or be happy with the fact that most won't watch this as 2 hour long video.

  4. Check out homosexuality and egg hatching behavior in male penguins
    In many animals reptiles, for example, sex is not determined by genetics but by environmental factors like temperature

  5. One thing that is not clear to me is the behavioral part of sexual attraction, which seems to be largely instinctive, ie likely to be partly genetically driven. How is instinctive behavior encoded genetically and how do those genes affect how we behave?
    In a sexual context, before we even try to understand out of the "norm" sexual behavior and its cause, can we even explain heteronormative sexual behavior?

  6. Using Malthusian theory to explain increased homosexuality in later sons wouldn't work, because limiting the number of males would not usually alter the number of offspring. You'd need to limit the number of females reproducing, since they have the next generation, and more females pass their genes to the next generation than males. Always.

  7. As interesting as I find this personally, I don't think people should fall in the trap of trying to "justify" homosexuality 'Because it's natural'. Homosexuality is alright because it doesn't harm anyone and it brings happiness to people.

    Be it a choice, genetically or environmentally predisposed or whatever else. It doesn't matter what we discover about the reason

  8. 46:55 this is very interesting. This may explain why natural selection did not "eliminate" homosexuality, because it is actually beneficial for females to produce offspring. It's like a female "selfish gene".
    Putting it in very simplistic words: It is as if the mitochondria says "I am getting pregnant very often and this is damaging my reproductive organs, so I am going to make my sons unable to reproduce so my daughters don't suffer the same as me"

  9. Yes, homoseuality is common across the animal kingdom- Near-universal to virtually ALL vertibrate species (but not all inidividuals, obviously)… Which makes it fundamentally different to the concept of "gender" which has ZERO empirical evidence, whatsoever- And DEFINITELY no basis for chemically-stunting the normal, natural development of 100% healthy, unconsenting 9yo children, based SOLELY on "just a social construct", with no more evidence than "ghosts" or "the soul".

    Of course, you can ALWAY find individuals of any species, doing behaviours typical of the opposite sex, like frequently see humans (whether they take cross-sex hormones or not). And there's some BIZARRE trend of people citing examples of INTERSEX conditions, as if this somehow (?!?) validates "gender" ideology- Spolier, it doesn't (unless you wanna claim that "sex" and "gender" ARE the same thing, in contradiction to all of "gender" ideology).

    EVERYONE, including children, should be free to act, dress, identify, etc however they want, REGARDLESS of their sex, AND their hormones (And adherents of "gender" pseudo-science SAY they believe this too… But their ACTIONS show otherwise…)

    Which means there's NO POSSIBLE REASON for giving puberty-bockers to children too young to give meaningfull consent to the very real harm puberty-blockers/cross-sex hormones do to their body (Google "Lupron, side effects", if you still believe that objectively VERY false "100% harmless and reversable" meme. FYI, the most common hormone-blockers given to kids, are "Lupron" and "Zoladex"- Trans-advocates reccommend giving these drugs as close to onset of puberty- Typically 9yo to 12yo… These are the EXACT drugs used to chemically-castrate sex-offenders… Which are also WELL-DOCUMENTED as very dangerous and hamful, in other applications like treating prostate cancer. So we know that 86% of ADULTS report SEVERE, LIFELONG side-effects from Lupron… But we don't even have data, on what long-term harm they do to 10yo children… And we're giving these dangerous drugs to 100% HEALTHY 10yos?!?)

    I know that most people THINK they're doing the right thing by "supporting trans kids", and YES- Support ALL kids, ESPECIALLY kids struggling with their own identity… But ask yourself this- Is there EVER a valid reason to give to give a 9yo in 100% perfect physical health, a drug that's well-documented to have VERY high rates of SEVERE side-effects treats NO injury, NO illness, it's not PREVENTING disease like a vaccine?

    If you really DO care about "trans kids", THEN MAYBE STOP CHEMICALLY STERILIZING THEM, many years before they can give valid consent to the harm that puberty-blockers/cross-sex hormones do to their 100% healthy bodies…

    …and ESPECIALLY stop doing this, based only on EXACTLY the same standard of evidence that Christians use to validate belief in "the soul", or "sin". ie "ZERO empirical evidence, but it FEELS true, to me!!", which is the ONLY evidence of "gender" we have. And… do WE EVEN have a "Hippocratic Oath"?!? Wtf does "first do no harm" EVEN MEAN, to you people?!?

    If you have ANY capacity for genuine, free, critical thought, then AT LEAST google "Lupron, side effects", and genuinely ask yourself "Is 'just a social construct' EVER a valid reason to give this drug to a 9yo, in perfect physical health?"

    I know you've been told otherwise, but I don't "hate trans people", I've support LGBT rights all my life, and still 100% support the right of CONSENTING ADULTS to do whatever they choose to their own body… but UNCONSENTING CHILDREN should be protected, not chemically-castrated… [& I can point you to MUTIPLE channels by trans people, saying the same as me- "Shapeshifter", "Buck Angel", the unfortunately-named (not by me, obv) "The offensive tr@nny", "Blaire White"- I know these are contraversial people, who I don't agree with on EVERYTHING… but I DO agree with them, on the apparently-contentious topic of "lets not chemically-mutilate 100% healthy 10yos"]

  10. 48:05 So here you talk about the statistical correlation between homosexuals, and the birth rates of their relatives. You put forth the idea that this may be the result of sexual antagonism, but it seems to me that the fraternal birth order effect that you described earlier would also explain this correlation. If mothers are having more children, then they will be having more subsequent males, thus increasing the likelihood that the younger ones will be homosexual.

    I think it's also worth pointing out that in our modern society the number of offspring that an individual has is less a function of their genetic fitness, and more a function of their sexual behavior. For example, many sexually active people engage in contraceptive practices, intentionally reducing the number of offspring they have, independent of their genetic fitness or sexual activity. In this contraceptive world, do we really think that the number of offspring an individual has is a reliable metric for statistical studies looking for correlations to support these hypotheses on the impact of genetics on sexuality?

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