Bilaterally Gynandromorphic Chickens And Why I’m Not “Scientifically” Male


I’m on vacation this week! This post originally appeared at Skepchick.

You know what this world needs more of? Misconceptions about transsexuality.

Wait… I think I got that backwards.

Right… there is absolutely no dearth whatsoever of misconceptions people have about transsexuality. Sometimes I feel like a sort of trans-advocate Sisyphus, perpetually pushing a boulder of education up a hill of myths, stereotypes, fear, hatred, ignorance, disinterest and general laziness. And really, I could spend the rest of my life just trying to debunk a small sub-set of the mistaken beliefs about us held in the mind of the general public.

Quite often, people tell me to pick my battles. So in the interest of actually listening to my friends for a change, that’s what I’m going to try to do today. Pick a battle. In this case, something that I really need to get out the way if I’m going to keep at this whole “discussing trans issues in the skeptic community” thing, something that I’ve come to regard as by far the most common misconception about transsexuality within skepticism: the belief that transsexuals are and always shall be “objectively”, “scientifically”, “biologically” members of their assigned sex.

I’ve noticed it repeatedly. Sometimes it is explained in a very condescending fashion… being told that my little definition of gender is simply brushing aside the science. That I’m pretentious to ignore the empirical reality and ask everyone to simply go along with my version of reality. Sometimes people can get very, very worked up about it, as though I’m threatening some extremely important fundamental framework upon which they’ve built their worldview. And I am, I suppose. But that doesn’t mean I’m wrong to do so.

It’s probably better if I not try to think too much about what exactly makes this belief so prevalent amongst skeptics, but the basic foundation of this belief starts with the assumption that the primary or best definition of sex is genetic. On the one side we have males, who are XY, and on the other we have females, who are XX, and sometimes we have various intersex conditions. It’s a tidy and unambiguous definition that provides comfortably hard answers. One’s DNA can’t be changed by current medical science, so under this definition a man will always be a man and can only be superficially changed to resemble a woman, and vice versa.

Of course, the first issue one takes with this view is that it is treating sex as being the same thing as gender and not really paying due consideration to that distinction. To put it briefly, sex is the physical body, while gender is identity, presentation, self-expression, interpersonal relationships, sociocultural role, etc. The common phrase (which is a tad inaccurate but gets the job done) is  “sex is between your legs, gender is between your ears”. An imperfect but fairly good and very readable breakdown of the basics of sex and gender can be found here.

However, we can go further with this. Even if we are looking at sex specifically, and disregarding gender with all its relative, subjective, soft-science-ness that is often so unappealing to some skeptics, we still find that the genetic definition of sex is not necessarily the best way of looking at things.

In truth, sex is a loose aggregation of a variety of variables. Chromosomes, yes, but also hormonal levels, genitals, secondary sexual characteristics, skeletal structure and so on. We consider each of these traits to be male, female, or not quite either, then collectively make some kind of rough, relatively subjective determination as to whether it is a male body, a female body or an intersexed body. This is not unlike the daily process of gendering we engage in every time we come across another human being. We make a quick, subconscious, intuitive weighing of the feminine cues against the masculine ones and make a judgment call on how we should mentally categorize that person. But even in a medical situation, where we are strictly looking at an individual’s anatomy, it can still be just as much of a subjective judgment call based on the relative weight being given to individual traits, and there’s no real reason to say the karyotype gets the final say.

If one makes the declaration that my genes are the “biological reality” that makes me “scientifically male”, it implies that things like my skin tone, my lack of body hair, my hormone levels, my breasts, my scent and all the other female or feminized aspects of my body are all somehow just in my head, figments of my imagination or “my version of reality”, or are merely cosmetic despite the fact that my breasts, for instance, are exactly as real, and developed through the exact same physical processes, as any other woman’s. Meanwhile saying that my completely invisible, anatomically irrelevant Y chromosome trumps everything else and dictates what my body really is. Pardon me if I don’t find that to be a terribly objective way of looking at things.

I’ve heard as an argument to prove how I’m really ‘scientifically’ male the hypothetical situation in which my horrifically disfigured, mutilated, unrecognizable corpse turns up in some abandoned building. A forensic pathologist, in an effort to determine my identity, conducts a DNA test and comes to the conclusion that I was male. Therefore, goes the argument, since the scientist using her scientific tests came to the conclusion that I’m male, that’s what I ‘scientifically’ am. But that’s only one particular inaccurate conclusion, made from the results of one particular test, that one particular type of scientist would make in one particular situation that has been contrived specifically to provide incomplete information. It’s easy to imagine another hypothetical: a doctor is trying to ascertain my identity based solely on a blood sample. He checks the hormone levels and comes to the conclusion that I’m a cisgender (not trans) woman at the mid-point in her cycle with a slightly low testosterone level. By that scientific test I’m ‘scientifically’ female. What makes the one inaccurate conclusion drawn from incomplete information more scientific and correct than the other inaccurate conclusion drawn from incomplete information?

I could stop here, since I feel I’ve made a fairly good case for why it doesn’t really make much sense to privilege genetic sex as being more objective and real than the other variables involved in sex, but I believe I can actually go further and make the case that chromosomes are actually less relevant for defining sex than other characteristics.

The truth is chromosomes don’t really play all that much of a role in human sexual differentiation. That work is done by hormones. Basically, all of our cells (and tissues) carry the genetic potential to express themselves in either female or male ways. Hormones come along and send a little message to activate certain genes or deactivate other ones. Estrogen comes in and says, “Okay, ladies! Time to do girl stuff!”… or testosterone struts on in and says “Listen, dudes. It’s time to man up. Hoo-hah!”.

I’ve also come across the misconception that there are such things as “male cells” and “female cells”. It doesn’t work like that. The Y chromosome doesn’t really do much. Basically, it only has one real function, and that’s to transform the embryonic ovaries into testes, which then triggers the cascade of hormones that signal the necessary mutations and cellular functions that create a male body. The rest of the Y chromosome is mostly just deteriorating junk DNA. And in the case of XX cells, one of those X chromosomes is deactivated. This means there is pretty much no functional difference between an XX cell and an XY cell at all.

We all start out as a sort of proto-female fetus. While an XY fetus is in utero, prenatal hormones trigger a series of changes that cause the developing fetus to acquire male characteristics. The proto-clitoris/proto-penis grows and fuses with the urethra. The testes descend. The vaginal canal closes. What would have been labia becomes a scrotum. The fact that male genitals are created out of the same tissues that would have been female genitals is precisely why MtF sexual reassignment surgery, vaginoplasty, is able to produce the highly functional, virtually indistinguishable results it does.

The only thing having “normal” XX or XY chromosomes is truly essential for is fertility, having functional ovaries or testes, and being able to have or produce ova and sperm. But we don’t go around claiming infertile men aren’t really men, or that if a man loses his testicles to cancer that he suddenly ceases being a man. Nor do we claim that a woman who has a hysterectomy or goes through menopause suddenly ceases being a woman. So fertility seems like a silly thing to suddenly consider all that important in determining the sex of a human being.

There’s an interesting intersex condition called CAIS, or Complete Androgen Insensitivity Syndrome. The cells in someone with this condition are completely unresponsive to androgenic hormones. Therefore, despite having an XY karyotype, the aforementioned sequence of physical changes that causes the fetus to become male never occur, and the infant is born being phenotypically indistinguishable from any other girl. They are assigned female, socialized as female, and pretty much lead completely normal female lives, with the only differences being that they are infertile, do not menstruate, have a slightly shallower vaginal canal, and may actually be somewhat more physically feminine than other women, given that almost all women do have a small amount of testosterone in their bodies.

As a contrast to this condition, I’d like to describe one of my all-time favourite biological weirdnesses: bilaterally gynandromorphic chickens. These are chickens that are, quite literally, split right down the middle of their bodies, being a rooster on one half and a hen on the other. Cool, yeah? This could never happen in humans.

This is caused by chimerism. Chimerism is when two embryos with unique DNA will fuse together and develop as a single fetus, resulting in an individual with two sets of DNA in a single body. This can occur in humans as well as chickens.

Sometimes a chimera will have one set of DNA be male and the other female. This is what happens in the case of our avian gynandromorphs. Since chickens don’t have as efficient a system of sexual differentiation as we do, and don’t work from a blank template that can express as either male or female depending on hormonal signals, their sexual differentiation actually is all about the genes. So the female DNA will express as hen and the male DNA will express as rooster.

Back to this not happening in humans: yes, intersexual chimerism can happen in humans. You can even end up with human beings who have one ovary and one testicle. But given that almost all sexual differentiation is a result of hormones, which are more or less evenly distributed throughout the body, you would never see any kind of stark split down the middle of a human with, say, a breast on one side and a flat chest on the other. Soft, hairless skin on one side and hairy, oily skin on the other. Instead, whatever secondary sexual characteristics were expressed would be expressed throughout the body. Some interesting patterns may develop, but that would be simply due to the difference in other genes between the two strands, not the difference in sexual chromosomes.

So please, I would ask all skeptically minded people everywhere: please educate yourselves about the science of sex and gender before making claims about it. And especially try to make sure you know the actual science involved before assuming that trans people are ignorant of it, or that we’re brushing it aside in favour of a purely relativistic, subjective, sociological approach. And please don’t tell us what aspects of our bodies are and are not a biological, objective reality. Thank you!

Now if you’ll excuse me, I’m in the mood for some KFC.

Comments

  1. Anders says

    Bravo!

    I’ll only add that trans people are using the scientific term for ‘male’ and ‘female’. When we determine sex in scientific studies we use a very simple method in the vast majority of the cases.

    We ask.

    For such a simple method it has astonishing sensitivity and specificity when compared against just about standard. And there’s really no reason to not have it as the standard. And of course, any self-respecting trans person would answer with their identified sex (which leaves genderqueer people out, but no system is perfect).

    Now, there may be rare occasions when you have to differentiate between cis and trans people. In that case, I would probably go with whether the driving hormone during puberty was testosterone or estrogen. A lot goes on during puberty which is why it’s vital to supply trans children with Lupron if possible. But, as I said, that’s rare.

  2. Sebor says

    This is supremely awesome and slightly creepy. One of my favourites, and probably the one that caused me to think and reconsider my opinions the most. Thank you very much.

  3. busterggi says

    Intersexed & chimeric humans are fascinating but the chicken is just plain weird.

    Please everyone, no photos of Bobby Cork, et al, to refute this article.

  4. D-Dave says

    Cool!

    Some of this I already knew, but a lot of new material. I especially like learning about sexual differentiation in other animals, like how the eggs of some species of reptiles can be temperature-controlled to favour either male or female offspring. Our ‘common sense’ notions of sex/gender are a lot like our common sense notions that made quantum mechanics and relativity so blatantly obvious, eh?

    • says

      That would be the ‘blatantly obvious’ that runs directly in contradiction to our physical intuition, right? As evolved large primates incapable of great speed we cannot perceive the effects of moving close to the speed of light, or observe the sub-microscopic effects predicted by the quantisation of mass and energy, and can only rationalise these by long study of the involved physics and mathematics.

      For the social analogy, since humans are sexually dimorphic we should regard the non-intersex, cisgender binary as the steady-state Newtonian realm that most cis people never seriously question; their sense of gender identity is so wedded to their physical sex that the possibility of having a gender identity in discord with one’s body seems counter-intuitive, like QM or relativity.

    • Arctic Ape says

      Jesus was allegedly a male individual born via parthenogenesis. This only makes sense if we assume that he was actually a bee, ant or some related species. That would also explain, why his mother is referred to as “Heavenly Queen” for just giving birth to him.

      Also: Jesus Hymenopteran Christ

  5. Karellen says

    […] I’m pretentious to ignore the empirical reality and ask everyone to simply go along with my version of reality. Sometimes people can get very, very worked up about it, as though I’m threatening some extremely important fundamental framework upon which they’ve built their worldview. And I am, I suppose. But that doesn’t mean I’m wrong to do so.

    It’s probably better if I not try to think too much about what exactly makes this belief so prevalent amongst skeptics…

    It’s probably because one of the most infuriating and persistent anti-rationalist memes out there is the straw-post-modern line of bullshit that there is no singular verifiable canonical version of reality or truth which can be discovered, but that every person has their own “narrative” which is equally valid.

    I call it straw-post-modern, because it’s not really the line that rigorous philosophical post-modernism embraces, but an extreme exaggeration thereof. However, it is actually embraced by all kinds of practitioners of various supernatural/magical woo, from some religious types who claim that mutually-contradictory religions can all be “true” at the same time (often while simultaneously denouncing atheism), through alt-med charlatans claiming that their tesimonials/anecdotes/ancient wisdom should be given as much credence as “western” scientific medicine, to those who are plain bonkers and insist on crap like that the Earth is flat for them.

    (More info at RationalWiki)

    This straw-post-modern argument, which comes out again and again, is complete bullshit. I’ve argued so many, many times. In every scientific experiment ever done, no-one has ever found a single one where the result is dependent on the “narrative” of the observer. There is not a single data point to suggest that there is not a single verifiable reality out there, and to suggest otherwise, or that your “narrative” is equally (or more) valid than reality is utter bollocks. Always has been, always will be.

    And yet, the argument will not die! So rationalists keep having to fight the same damn battle, making the same damn arguments, again, and again, and again.

    Eventually, it becomes a reflex.

    Sometimes the reflex is wrong. Sometimes someone will be making a valid post-modern point. Sometimes someone will be making an analogy about the real world using an alternative point of view without trying to convince us that it’s actually true. And sometimes, someone will ask us to consider something to do with human perception/understanding that only makes sense in terms of individual perspectives – where there is no canonical “external reality” – like you are doing here.

    But that reflex is still there. It’s been ingrained into us over the course of many, many frustrating arguments, by idiots who really don’t have a clue about how the universe works. All you need to do is hear the words “narrative” or “version of reality”, and *bam*, your adrenaline is flowing and you’re marshalling your smackdown.

    No, I don’t know how to fix it. :-(

    • says

      It’s probably because one of the most infuriating and persistent anti-rationalist memes out there is the straw-post-modern line of bullshit that there is no singular verifiable canonical version of reality or truth which can be discovered, but that every person has their own “narrative” which is equally valid.

      Though personally constructed narratives are not necessarily on equal ground with regards to conforming to reality and fact, they are definitely strongly influenced by perspective. This doesn’t conflict with your points, especially about the topics at hand, but it has some weird effects in general.

      Using a physics example, time is relative. The observation of events can actually be ordered completely differently merely because one had a different frame of reference from another. This is most easily noticed in observing astronomical events. For example, we observe a supernova at time T1 here on Earth in one reference frame. It is observed at a different time T2 on the other side of the galaxy. If you take the location of the supernova as a variable and move it around the galaxy, it is straightforward to show how the event could have been seen as either before or after another arbitrarily chosen local comparison event at either of the two reference points. This is a result of having the speed of light as essentially a universal speed limit on the propagation of information. It implies that all observations are inherently imperfect to some degree, and thus that time is not absolute.

      Although this is an example chosen to demonstrate how point of view can cause extreme distortion in the perception of events, a similar concept applies in much more subtle and less obvious ways here on Earth. Since our ability and willingness to observe is always finite, our views of society are shaped in large part by personal experience more-so than an objective statement of reality. Understanding this helps greatly to explain why the attitudes, for instance, of people who have transgender friends are typically so different from those who do not. Or along the many other lines of privilege and power…

      What label we give to questioning bad assumptions and acknowledging our limitations isn’t particularly important. I’ve seen some call this post-modernism, some call it science, some call it philosophy, and yet others create their own name.

      What’s important is that we actually do it.

    • Zoe says

      There is not a single data point to suggest that there is not a single verifiable reality out there, and to suggest otherwise, or that your “narrative” is equally (or more) valid than reality is utter bollocks.

      I give you the . Yes, people abuse and misconstrue post-modern thought quite regularly, but watch out that you’re not too quick to simplify the world. One doesn’t have to believe in fairy tales to recognize that our reality is stranger than any simple set of rules can acknowledge. Reality behaves differently when it is being observed than when it isn’t.

      • Karellen says

        But reality doesn’t behave differently depending on the cultural background of the observer. Also, even though that part of reality is “created by” the observer, all observers of that part of reality will observe the same thing. If one person observes a photon as a particle, another will not observe the same photon as a self-interfering wave.

        Heisenberg’s Uncertaintly principle is similar – the more accurately you measure one value, the more you perturb another reducing the accuracy with which you can know it, but that perturbation and the level of uncertainty is not dependent on any characteristic of the device doing the measurement.

  6. Megan says

    Ah, the “hypothetical situation in which my horrifically disfigured, mutilated, unrecognizable corpse turns up in some abandoned building” thing. Completely stupid, yes, but why do the people who bring this up always sound a little like they’re hinting that it might not be such a hypothetical situation if I don’t watch myself around them?

    • sc_69fc3053efe3b6d2893944ca582d740c says

      It might not be, even if you do watch yourself around them.

      You’re not the one in danger.

      Trans women have 17 times the chance of being murder victims than you do. The FBI confirms that most of the deaths aren’t “clean kills” either, torture, dismemberment and burning are often involved.

      Trans activists – including those who have high public profiles on the net – are particularly singled out. So are Trans women of color.

      The latest case, Agnes Torres:

      Mexican transgender activist Agnes Torres was found dead this week outside her home in Puebla, Mexico. Her neck had been slashed, her body burned in signs she had been tortured.

      It’s a hazard of the profession, like car crashes are to Formula One drivers, or burning to death is to firefighters. We’re aware of it, try not to let fear rule our lives, and it’s sometimes difficult remembering that everyone else doesn’t live with the same constant threat.

      It’s not as of the chances are objectively that great. Worse casualty rate than US Forces in Afghanistan, true, and we all know personally at least one of the victims, but not as bad as hitting Omaha Beach in WWII. Even Trans women of colour have 7 chances in 8 of not being murdered, and the risk for the author and myself is nowhere near that high.

      We tend not to think about it, or mention it, as it’s really not germane to the issue of education about the biology. As I said, sometimes we forget that others have different perspectives, and think a phrase like “the hypothetical situation in which my horrifically disfigured, mutilated, unrecognizable corpse turns up in some abandoned building” is creepy, rather than just a low-probability event we have to accept will happen to some of us one day.

      • says

        “Trans activists – including those who have high public profiles on the net – are particularly singled out.”

        Thanks for that, Ms. I Know Who You Are And You Totally Have A High Profile Too. ;)

      • Anders says

        Ok, that’s depressing. And adds some weight to my Queer-Self-Defence training proposal. Not that it helps against a knife…

        Also, pet peeve – 17 times larger risk, not chance. Sorry, it’s just my OCD traits coming to the fore.

        • Rilian says

          What’s the difference in meaning between saying “greater risk” and “greater chance”? They seem the same to me.

          • Anders says

            Risk is probability something negative happens.

            Chance is probability something positive happens.

          • Rilian says

            Chance just means the probability of something happening. It’s not positive or negative.

          • Anders says

            It’s possible that it’s different in English. In Swedish, chance = good, risk = bad.

            It’s a nitpick anyway.

          • says

            Yeah, in English, risk means possibility of something “bad”, but chance is simply neutral. Can be good or bad. There’s no word for a specifically positive possibility, though “luck” and “auspicious” are related.

      • says

        By the way, I think Megan is herself trans. She’s talking about the situation I described, where a cis person brings up this hypothetical of our murder to a trans person as a way of making their point about genetic sex, and it having a slightly threatening undertone.

        • Anders says

          Any way, who gives a shit? Yes, that test is appropriate for that specific situation… but that doesn’t mean it’s your true sex. Different situations call for different definitions – and the relevant definition for almost all normal-day situations is self-identification.

          • says

            Well yeah, I just mean that… um… Person Posting Anonymously seemed to have mistakenly interpreted Megan to have been cis and creeped out by a trans person bringing that up, rather than being a trans person who’s creeped out when cis people bring it up.

  7. Rilian says

    Man and woman aren’t scientific terms, they’re social terms. So when someone insists that you’re really this or that, they’re saying that THEY get to decide what you are, socially. In most circumstances, individuals just be themselves, and everyone else has to fucking deal with it. But if someone gets a little too weird, a little too far away from the normal bubble, suddenly people make up all these fake and stupid rules about how “you don’t get to decide who you are socially… society decides!!!”

  8. Ringo says

    Thanks for reposting this, I was just having a discussion on this topic with a coworker who just doesn’t get it. I printed it for her since she doesn’t have internet, and I hope it helps… If not I’ll have to delve into the archives. :)

  9. Louis says

    I love this article. I found it a while ago when I was researching chimerism (I have somatic mosaicism, so chimerism is a possibility in my case). This was the article that got me reading this blog in the first place.

  10. says

    Natalie, you’re not “Scientifically Male” based on the data on chickens, stuff that I don’t really understand? Would it matter to me or anyone else if the chicken stuff was ambiguous, or pointed towards the opposite of what you’ve concluded?

    Nope. As much as you’ve described it, none of that stuff really matters when it comes down to brass tacks. Since that’s the way it is, as far as I can tell all that stuff is meaningless to me too.

    This shit irritates me in a sense, because we shouldn’t need these conversations to take place in public all the time, and it is sad that we DO need them. Natalie, your’re a chick (I know you don’t need me to make that declaration!) For 99.99999999999% of the human race, that should be enough. Your non-standard chick biology should only be any sort of issue for the 0.00000000001% of people who you might be physically intimate with… and there should be enough people who don’t care about that stuff that things should be easy for you.

    In a perfect world, that’s how it would work. In a better world than the one we live in, there would at least be judo chops dished out to the bigots. I dunno. You’re a chick. Trans women are chicks, trans men are dudes. I know it is difficult for people, but it sure isn’t particularly complicated.

  11. Tido says

    What always irritates me about this genetic argument is how it assumes everyone knows their chromosomes and probably those of others too. Most people don’t, they just use their biology lessons to guess from their identity and body shape what their sex chromosomes probably are. And that’s the hard scientific data that proves someone else’s identity is invalid?

    “I’m identify as male, my body is that of a male, therefore my chromosomes are probably XY, so that scientifically proofs my identifying as male is correct…” oh please, circular argument anyone?

  12. Anders says

    I know we’re not supposed to lead radical feminists here, but I still think it would be good for them to read this article. I don’t expect any spontaneous conversion events, but it might just make them think. I know, I’m a hopeless optimist.

    Would it be ok to lead them to the original site at Skepchick? Or is that still too close=

      • Anders says

        I just like to give credit where credit’s due, but I guess I’ll have to make the points myself. Luckily our circumstances are different – they can’t really touch me. I’ll carry your banner, but with your name crossed out.

        Speaking of transphobes, are you going to write anything about Adrienne Rich?

        • says

          Probably not. Not much to say about it, really. “Oh, btw, while you’re mourning this ‘great feminist’, please remember she was buddy-buddy with Janice Raymond and helped her write The Transsexual Empire, one of the most hateful cis-supremacist screeds to ever tarnish the English language. And also her poetry kind of sucked” would pretty much cover it.

          • Anders says

            I twittered with a friend who had written a Swedish blog post about her. She didn’t even know that Rich was transphobic; my guess is that people will quietly forget about the bad parts and concentrate on the good parts. In twenty years only experts will even remember that she was a transphobe.

            And that’s kind of a good thing, even if it is rewriting history. It shows that transphobia is something people are ashamed of, something they don’t want to remember that one of their heroes did. And so, slowly we make progress.

      • Astrid_H says

        I’m slightly confused. I identify as a radical feminist but I didn’t know that transphobia was implied in that. Anyway, great article, I’ll be sure to remember these points and bring them up the next time someone is being ignorant about these issues.

        • Rilian says

          That’s what I was thinking. I was wondering why radical feminist would mean hating transgendered people.

        • Rasmus says

          My understanding is that there is a subset of radical feminists who don’t think that transgenderism is a legitimate thing, at least not in the form that’s supported by mainstream medicine and psychiatry. This google search may be useful if you want to see some of the stuff that people have been saying about it.

  13. criss says

    this was a very thoughtfully-written post, the first of yours that I’ve read, and I look forward to reading more. the issue of explaining transsexality, sex, and gender to the misinformed or skeptical is an all too common challenge for some of us. as intersex and transsexual, i really appreciate the arguments you laid out here, it actually makes things a little easier to explain. also the chicken thing started me off on a quest to learn more about bilaterally gynandromorphic birds, and i found that there have been cardinals photographed with this condition, specifically here: http://www.ilbirds.com/images/cardinal/comp-1_6.jpg, which is awesome because my all-male high school logo is a red male cardinal, which i modified to represent the female colors, and i never knew there were such distinctly intersex cardinals out there!

  14. sc_69fc3053efe3b6d2893944ca582d740c says

    One’s DNA can’t be changed by current medical science

    Point of Order, Madame Speaker!

    Yes, it can.

    Bone marrow transplant recipients have their bodies gradually become genetically identical to the donor, as senescent cells get replaced by stem cells from the bone-marrow. Even ovaries and brain cells.

    See:

    Bone marrow-derived cells from male donors can compose endometrial glands in female transplant recipients by Ikoma et al in Am J Obstet Gynecol. 2009 Dec;201(6):608.e1-8

    Transplanted human bone marrow cells generate new brain cells by Crain BJ, Tran SD, Mezey E. in J Neurol Sci. 2005 Jun 15;233(1-2):121-3

    It doesn’t change the recipient’s sex of course, because chromosomes don’t determine that, they just bias the odds of development in the womb one way or the other.

    From J Clin Endocrinol Metab. 2008 Jan;93(1):182-9

    PATIENTS: A 46,XY mother who developed as a normal woman underwent spontaneous puberty, reached menarche, menstruated regularly, experienced two unassisted pregnancies, and gave birth to a 46,XY daughter with complete gonadal dysgenesis.

    Apart from that, a flawless article.

  15. valeriekeefe says

    I’ve said it before and I’ll say it again: Sapient species, sexually dimorphic neurology… neurological sex, or gender identity as we call the articulation of that sex, is the only legitimate metric of sex.

    If you don’t believe me, ask yourself if a sapient human brain in a jar has human rights, is human… now ask yourself if a functioning, brainless body, driven by a non-sapient computer is human.

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